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1 -SDMX Technical Specification|Statistical data and metadata exchange
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10 10  
11 11  = 1 Introduction =
12 12  
13 -The [[Statistical Data and Metadata Exchange>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] ([[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]]) initiative (https:~/~/www.sdmx.org) sets standards that can facilitate the exchange of statistical data and metadata using modern information technology.
13 +The Statistical Data and Metadata Exchange (SDMX) initiative (https:~/~/www.sdmx.org) sets standards that can facilitate the exchange of statistical data and metadata using modern information technology.
14 14  
15 -The [[SDMX Technical Specifications>>doc:sdmx:Glossary.SDMX Technical Specification.WebHome]] are organised into several discrete sections.
15 +The SDMX Technical Specifications are organised into several discrete sections.
16 16  
17 -The following are published on the [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] website  ([[__https:~~/~~/www.sdmx.org__>>https://https:www.sdmx.org]]):
17 +The following are published on the SDMX website ([[__https:~~/~~/www.sdmx.org__>>https://https:www.sdmx.org]]):
18 18  
19 19  **Section 1** **Framework for SDMX Technical Standards** – this document providing an introduction to the technical standards.
20 20  
21 -**Section 2** **SDMX Information Model** - the [[SDMX information model>>doc:sdmx:Glossary.SDMX Information Model.WebHome]] is a standardised object model for modelling [[statistical domains>>doc:sdmx:Glossary.Statistical subject-matter domain.WebHome]] centring on the structure of their data and [[metadata sets>>doc:sdmx:Glossary.Metadata set.WebHome]], the coding schemes used for classification, and the rules for controlling the exchange of data and metadata between organisations. This document provides a UML specification with supporting narrative.
21 +**Section 2** **SDMX Information Model** - the SDMX information model is a standardised object model for modelling statistical domains centring on the structure of their data and metadata sets, the coding schemes used for classification, and the rules for controlling the exchange of data and metadata between organisations. This document provides a UML specification with supporting narrative.
22 22  
23 -**Section 5** **SDMX Registry Specification** – an [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] ‘registry’ acts as a repository for [[structural metadata>>doc:sdmx:Glossary.Structural metadata.WebHome]] and provisioning information, and a registry of data and metadata sources. This document sets out the specification.
23 +**Section 5** **SDMX Registry Specification** – an SDMX ‘registry’ acts as a repository for structural metadata and provisioning information, and a registry of data and metadata sources. This document sets out the specification.
24 24  
25 -**Section 6** **SDMX Technical Notes** – detailed technical guidance for implementors of the [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] standard.
25 +**Section 6** **SDMX Technical Notes** – detailed technical guidance for implementors of the SDMX standard.
26 26  
27 -The following are published on the GitHub repository of the [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] Standards Technical Working Group  ([[__https:~~/~~/github.com/sdmx-twg__>>https://https:github.comsdmx-twg]]): sdmx-twg/sdmx-rest – REST API
27 +The following are published on the GitHub repository of the SDMX Standards Technical Working Group ([[__https:~~/~~/github.com/sdmx-twg__>>https://https:github.comsdmx-twg]]): sdmx-twg/sdmx-rest – REST API
28 28  
29 -Technical specifications for the [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] RESTful web services application programming interfaces (API).
29 +Technical specifications for the SDMX RESTful web services application programming interfaces (API).
30 30  
31 31  (% class="wikigeneratedid" id="Hsdmx-twg2Fsdmx-ml2013SDMX-ML" %)
32 32  **sdmx-twg/sdmx-ml – SDMX-ML**
33 -Technical specifications for the XML transmission format including XSD schemas, documentation and samples for data, structure and [[reference metadata>>doc:sdmx:Glossary.Reference metadata.WebHome]] messages.
33 +Technical specifications for the XML transmission format including XSD schemas, documentation and samples for data, structure and reference metadata messages.
34 34  
35 35  (% class="wikigeneratedid" id="Hsdmx-twg2Fsdmx-json2013SDMX-JSON" %)
36 36  **sdmx-twg/sdmx-json – SDMX-JSON**
37 -Technical specifications for the JSON transmission format including documentation, schemas and samples for data, structure and [[reference metadata>>doc:sdmx:Glossary.Reference metadata.WebHome]] messages.
37 +Technical specifications for the JSON transmission format including documentation, schemas and samples for data, structure and reference metadata messages.
38 38  
39 39  (% class="wikigeneratedid" id="Hsdmx-twg2Fsdmx-csv2013SDMX-CSV" %)
40 40  **sdmx-twg/sdmx-csv – SDMX-CSV**
41 -Technical specifications for the [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]]-CSV transmission format for ‘comma-separated values’ (CSV) data and [[reference metadata>>doc:sdmx:Glossary.Reference metadata.WebHome]].
41 +Technical specifications for the SDMX-CSV transmission format for ‘comma-separated values’ (CSV) data and reference metadata.
42 42  
43 43  The following sections are obsolete:
44 44  
45 -Section 3 - [[SDMX-ML>>doc:sdmx:Glossary.SDMX-ML.WebHome]] - replaced by the sdmx-twg/sdmx-ml GitHub repository
45 +Section 3 - SDMX-ML - replaced by the sdmx-twg/sdmx-ml GitHub repository
46 46  
47 -Section 4 - [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]]-EDI
47 +Section 4 - SDMX-EDI
48 48  
49 -Section 7 - API - replaced by the sdmx-twg/sdmx-rest GitHub repository [[VTL>>doc:sdmx:Glossary.Validation and transformation language.WebHome]]
49 +Section 7 - API - replaced by the sdmx-twg/sdmx-rest GitHub repository VTL
50 50  
51 -In July 2020 the [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] 2.1 specifications were revised to add support for the [[Validation and Transformation Language>>doc:sdmx:Glossary.Validation and transformation language.WebHome]] ([[VTL>>doc:sdmx:Glossary.Validation and transformation language.WebHome]]). For 3.0, the [[VTL>>doc:sdmx:Glossary.Validation and transformation language.WebHome]] specification has been updated to align with changes to the information model and other modifications to the Standard such as the introduction of Semantic Versioning for the versioning of [[structural metadata>>doc:sdmx:Glossary.Structural metadata.WebHome]] [[artefacts>>doc:sdmx:Glossary.Artefact.WebHome]]. Section 2 (Information Model) sets out details of the ‘Transformation and Expressions’ package for defining and managing [[VTL>>doc:sdmx:Glossary.Validation and transformation language.WebHome]] 2.0 programs and Section 6 (Technical Notes) provides detailed guidance on implementing and using [[VTL>>doc:sdmx:Glossary.Validation and transformation language.WebHome]] with [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]].
51 +In July 2020 the SDMX 2.1 specifications were revised to add support for the Validation and Transformation Language (VTL). For 3.0, the VTL specification has been updated to align with changes to the information model and other modifications to the Standard such as the introduction of Semantic Versioning for the versioning of structural metadata artefacts. Section 2 (Information Model) sets out details of the ‘Transformation and Expressions’ package for defining and managing VTL 2.0 programs and Section 6 (Technical Notes) provides detailed guidance on implementing and using VTL with SDMX.
52 52  
53 53  = 2 Change History =
54 54  
55 -The 2.0 (% style="color:#e74c3c" %)version(%%) of this standard represented a significant increase in scope, and also provided more complete support in those areas covered in the (% style="color:#e74c3c" %)version(%%) 1.0 specification. (% style="color:#e74c3c" %)Version(%%) 2.0 of this standard is backward-compatible with (% style="color:#e74c3c" %)version(%%) 1.0, so that existing implementations can be easily migrated to conformance with (% style="color:#e74c3c" %)version(%%) 2.0.
55 +The 2.0 version of this standard represented a significant increase in scope, and also provided more complete support in those areas covered in the version 1.0 specification. Version 2.0 of this standard is backward-compatible with version 1.0, so that existing implementations can be easily migrated to conformance with version 2.0.
56 56  
57 -The 2.1 (% style="color:#e74c3c" %)version(%%) of this standard represents a set of changes resulting from several years of implementation experience with the 2.0 standard. The changes do not represent a major increase in scope or functionality, but do correct some bugs, and add functionalities in some cases. Major changes in [[SDMX-ML>>doc:sdmx:Glossary.SDMX-ML.WebHome]] include a much stronger alignment of the XML Schemas with the Information Model, to emphasize inheritance and object-oriented features, and increased precision and flexibility in the attachment of metadata reports to specific objects in the [[SDMX Information Model>>doc:sdmx:Glossary.SDMX Information Model.WebHome]].
57 +The 2.1 version of this standard represents a set of changes resulting from several years of implementation experience with the 2.0 standard. The changes do not represent a major increase in scope or functionality, but do correct some bugs, and add functionalities in some cases. Major changes in SDMX-ML include a much stronger alignment of the XML Schemas with the Information Model, to emphasize inheritance and object-oriented features, and increased precision and flexibility in the attachment of metadata reports to specific objects in the SDMX Information Model.
58 58  
59 -The 3.0 (% style="color:#e74c3c" %)version(%%) incorporates new features, improvements and changes arising from the collective knowledge gained from a decade of operating experience with the 2.1 standard. In pursuit of modernisation and simplification, features considered obsolete have been deprecated – in particular the EDI transmission format, the lesser-used XML data messages and the SOAP web services API. Many areas remain backwardly compatible with 2.1, but there are some breaking changes where the information model has been redesigned to better support practical use case. Structure mapping and [[reference metadata>>doc:sdmx:Glossary.Reference metadata.WebHome]] are examples. The opportunity has been taken to revise the RESTful web services API which is also not backwardly compatible, but benefits from a rationalisation and better organisations of resources, and a much richer data query URL syntax.
59 +The 3.0 version incorporates new features, improvements and changes arising from the collective knowledge gained from a decade of operating experience with the 2.1 standard. In pursuit of modernisation and simplification, features considered obsolete have been deprecated – in particular the EDI transmission format, the lesser-used XML data messages and the SOAP web services API. Many areas remain backwardly compatible with 2.1, but there are some breaking changes where the information model has been redesigned to better support practical use case. Structure mapping and reference metadata are examples. The opportunity has been taken to revise the RESTful web services API which is also not backwardly compatible, but benefits from a rationalisation and better organisations of resources, and a much richer data query URL syntax.
60 60  
61 -The 3.1 (% style="color:#e74c3c" %)version(%%) provides supports for data models to increase dimensionality over time without impacting existing data collections. The Data (% style="color:#e74c3c" %)Constraint(%%) model was adjusted to separate concerns of data reporting and data dissemination.
61 +The 3.1 version provides supports for data models to increase dimensionality over time without impacting existing data collections. The Data Constraint model was adjusted to separate concerns of data reporting and data dissemination.
62 62  
63 63  == 2.1 Major Changes from 1.0 to 2.0 ==
64 64  
65 -* **[[Reference Metadata>>doc:sdmx:Glossary.Reference metadata.WebHome]]**: In addition to describing and specifying data structures and formats (along with related [[structural metadata>>doc:sdmx:Glossary.Structural metadata.WebHome]]), the (% style="color:#e74c3c" %)version(%%) 2.0 specification also provides for the exchange of metadata which is distinct from the [[structural metadata>>doc:sdmx:Glossary.Structural metadata.WebHome]] in the 1.0 (% style="color:#e74c3c" %)version(%%). This [[category>>doc:sdmx:Glossary.Category.WebHome]] includes “reference” metadata (regarding data quality, methodology, and similar types – it can be configured by the user to include whatever (% style="color:#e74c3c" %)concepts(%%) require reporting); metadata related to data provisioning ([[release calendar>>doc:sdmx:Glossary.Release policy - release calendar.WebHome]] information, description of the data and metadata provided, etc.); and metadata relevant to the exchange of categorization schemes.
66 -* **[[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] Registry**: Provision is made in the 2.0 standard for standard communication with registry services, to support a data-sharing model of statistical exchange. These services include registration of data and metadata, querying of registered data and metadata, and [[subscription>>doc:sdmx:Glossary.Subscription.WebHome]]/notification.
67 -* **[[Structural Metadata>>doc:sdmx:Glossary.Structural metadata.WebHome]]**: The support for exchange of statistical data and related [[structural metadata>>doc:sdmx:Glossary.Structural metadata.WebHome]] has been expanded. Some support is provided for qualitative data; data cube structures are described; [[hierarchical code lists>>doc:sdmx:Glossary.Hierarchical code list.WebHome]] are supported; relationships between data structures can be expressed, providing support for extensibility of data structures; and the description of functional dependencies within cubes are supported.
65 +* **Reference Metadata**: In addition to describing and specifying data structures and formats (along with related structural metadata), the version 2.0 specification also provides for the exchange of metadata which is distinct from the structural metadata in the 1.0 version. This category includes “reference” metadata (regarding data quality, methodology, and similar types – it can be configured by the user to include whatever concepts require reporting); metadata related to data provisioning (release calendar information, description of the data and metadata provided, etc.); and metadata relevant to the exchange of categorization schemes.
66 +* **SDMX Registry**: Provision is made in the 2.0 standard for standard communication with registry services, to support a data-sharing model of statistical exchange. These services include registration of data and metadata, querying of registered data and metadata, and subscription/notification.
67 +* **Structural Metadata**: The support for exchange of statistical data and related structural metadata has been expanded. Some support is provided for qualitative data; data cube structures are described; hierarchical code lists are supported; relationships between data structures can be expressed, providing support for extensibility of data structures; and the description of functional dependencies within cubes are supported.
68 68  
69 69  == 2.2 Major Changes from 2.0 to 2.1 ==
70 70  
71 -* **Web-Services-Oriented Changes:** Several organizations have been implementing web services applications using [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]], and these implementations have resulted in several changes to the specifications. Because the nature of [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] web services could not be anticipated at the time of the original drafting of the specifications, the web services guidelines have been completely re-developed.
72 -* **Presentational Changes: **Much work has gone into using various technologies for the visualization of [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] data and metadata, and some changes have been proposed as a result, to better leverage this graphical visualization. These changes are largely to leverage the [[Cross-domain Concepts>>doc:sdmx:Glossary.Cross-domain concept.WebHome]] of the Content Oriented Guidelines.
71 +* **Web-Services-Oriented Changes:** Several organizations have been implementing web services applications using SDMX, and these implementations have resulted in several changes to the specifications. Because the nature of SDMX web services could not be anticipated at the time of the original drafting of the specifications, the web services guidelines have been completely re-developed.
72 +* **Presentational Changes: **Much work has gone into using various technologies for the visualization of SDMX data and metadata, and some changes have been proposed as a result, to better leverage this graphical visualization. These changes are largely to leverage the Cross-domain Concepts of the Content Oriented Guidelines.
73 73  * **Consistency Issues:** There have been some areas where the draft specifications were inconsistent in minor ways, and these have been addressed.
74 74  * **Clarifications in Documentation:** In some cases, it has been identified that the documentation of specific fields within the standard needed clarification and elaboration, and these issues have been addressed.
75 -* **Optimization for XML Technologies:** Implementation has shown that it is possible to better organize the XML schemas for use within common technology development tools which work with XML. These changes are primarily focused on leveraging the objectoriented features of W3C XML Schema to allow for easier processing of [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] data and metadata.
76 -* **Consistency between the [[SDMX-ML>>doc:sdmx:Glossary.SDMX-ML.WebHome]] and the [[SDMX Information Model>>doc:sdmx:Glossary.SDMX Information Model.WebHome]]: **Certain aspects of the XML schemas and UML model have been more closely aligned, to allow for easier comprehension of the [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] model.
75 +* **Optimization for XML Technologies:** Implementation has shown that it is possible to better organize the XML schemas for use within common technology development tools which work with XML. These changes are primarily focused on leveraging the objectoriented features of W3C XML Schema to allow for easier processing of SDMX data and metadata.
76 +* **Consistency between the SDMX-ML and the SDMX Information Model: **Certain aspects of the XML schemas and UML model have been more closely aligned, to allow for easier comprehension of the SDMX model.
77 77  * **Technical Bugs:** Some minor technical bugs have been identified in the registry interfaces and elsewhere. These bugs have been addressed.
78 78  * **Support for Non-Time-Series Data in the Generic Format: **One area which has been extended is the ability to express non-time-series data as part of the generic data message.
79 -* **Simplification of the [[data structure definition>>doc:sdmx:Glossary.Data structure definition.WebHome]] - specific message types: **Both time series ((% style="color:#e74c3c" %)version(%%) 2.0 Compact) and non-time series [[data sets>>doc:sdmx:Glossary.Data set.WebHome]] ((% style="color:#e74c3c" %)version(%%) 2.0 Cross Sectional) use the same underlying structure for a structure-specific formatted message, which is specific to the [[Data Structure Definition>>doc:sdmx:Glossary.Data structure definition.WebHome]] of the data set.
79 +* **Simplification of the data structure definition - specific message types: **Both time series (version 2.0 Compact) and non-time series data sets (version 2.0 Cross Sectional) use the same underlying structure for a structure-specific formatted message, which is specific to the Data Structure Definition of the data set.
80 80  * **Simplification and better support for the metadata structure: **New use cases have been reported and these are now supported by a re-modelled metadata structure definition.
81 -* **Support for partial [[item schemes>>doc:sdmx:Glossary.Item scheme.WebHome]] such as a [[code list>>doc:sdmx:Glossary.Code list.WebHome]]: **The (% style="color:#e74c3c" %)concept(%%) of a partial (subset) [[item scheme>>doc:sdmx:Glossary.Item scheme.WebHome]] such as a partial [[code list>>doc:sdmx:Glossary.Code list.WebHome]] for use in exchange scenarios has been introduced**.**
81 +* **Support for partial item schemes such as a code list: **The concept of a partial (subset) item scheme such as a partial code list for use in exchange scenarios has been introduced**.**
82 82  
83 83  == 2.3 Major Changes from 2.1 to 3.0 ==
84 84  
85 -[[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] (% style="color:#e74c3c" %)version(%%) 3.0 introduces new features, improvements and changes to the Standard in the following key areas:
85 +SDMX version 3.0 introduces new features, improvements and changes to the Standard in the following key areas:
86 86  
87 -(% class="wikigeneratedid" id="HInformationModel" %)
88 -**Information Model**
87 +==== Information Model ====
89 89  
90 -* Simplification and improvement of the [[reference metadata>>doc:sdmx:Glossary.Reference metadata.WebHome]] model
89 +* Simplification and improvement of the reference metadata model
91 91  * Support for microdata
92 92  * Support for geospatial data
93 -* Support for [[code list>>doc:sdmx:Glossary.Code list.WebHome]] extension and discriminated union of [[code lists>>doc:sdmx:Glossary.Code list.WebHome]]
92 +* Support for code list extension and discriminated union of code lists
94 94  * Improvements to structure mapping
95 -* Improvements to [[code>>doc:sdmx:Glossary.Code.WebHome]] [[hierarchies>>doc:sdmx:Glossary.Hierarchy.WebHome]] for data discovery
96 -* Improvements to (% style="color:#e74c3c" %)constraints
94 +* Improvements to code hierarchies for data discovery
95 +* Improvements to constraints
97 97  
98 -(% class="wikigeneratedid" id="HVersioningofStructuralMetadataArtefacts" %)
99 -**Versioning of Structural Metadata Artefacts**
97 +==== Versioning of Structural Metadata Artefacts ====
100 100  
101 -• Adoption of the three-number semantic versioning standard for [[structural metadata>>doc:sdmx:Glossary.Structural metadata.WebHome]] [[artefacts>>doc:sdmx:Glossary.Artefact.WebHome]] ([[__https:~~/~~/semver.org__>>https://https:semver.org]])
99 +• Adoption of the three-number semantic versioning standard for structural metadata artefacts ([[__https:~~/~~/semver.org__>>https://https:semver.org]])
102 102  
103 -(% class="wikigeneratedid" id="HRESTWebServicesApplicationProgrammingInterface28API29" %)
104 -**REST Web Services Application Programming Interface (API)**
101 +==== REST Web Services Application Programming Interface (API) ====
105 105  
106 106  * Change to a single ‘structure’ resource for structure queries simplifying the REST API specification by reducing the number of resources to five
107 107  * Improvements to data queries
108 -* Improvements to [[reference metadata>>doc:sdmx:Glossary.Reference metadata.WebHome]] queries
109 -* Support for [[structural metadata>>doc:sdmx:Glossary.Structural metadata.WebHome]] maintenance using HTTP PUT, POST and DELETE verbs
105 +* Improvements to reference metadata queries
106 +* Support for structural metadata maintenance using HTTP PUT, POST and DELETE verbs
110 110  
108 +==== SOAP Web Services API ====
111 111  
110 +• The SOAP web services API has been deprecated with version 3.0 standardising on REST
112 112  
113 -The [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] standards specified here are designed to support the requirements of all of these automation processes and technologies.
112 +==== XML, JSON, CSV and EDI Transmission formats ====
114 114  
115 -== 3.3 Statistical Data and Metadata ==
114 +* The SDMX-ML, SDMX-JSON and SDMX-CSV specifications have been extended and modified where needed to support the new features and changes such as reference metadata and microdata
115 +* Obsolete SDMX-ML data message variants including Generic, Compact, Utility and Cross-sectional have been deprecated standardising on Structure Specific Data as the sole XML format for data exchange
116 +* The SDMX-EDI transmission format for structures and data has been deprecated
117 +* The organisation of structures into ‘collections’ in SDMX-ML and SDMX-JSON structure messages has been flattened and simplified
118 +* The option to reference structures in SDMX-ML and SDMX-JSON messages using Agency, ID and Version has been deprecated with URN now exclusively used for all non-local referencing purpose
116 116  
117 -To avoid confusion about which "data" and "metadata" are the intended content of the [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] formats specified here, a statement of scope is offered. Statistical "data" are sets of often numeric observations which typically have time associated with them. They are associated with a set of metadata values, representing specific (% style="color:#e74c3c" %)concepts(%%), which act as identifiers and descriptors of the data. These metadata values and (% style="color:#e74c3c" %)concepts(%%) can be understood as the named [[dimensions>>doc:sdmx:Glossary.Dimension.WebHome]] of a multi-dimensional co-ordinate system, describing what is often called a "cube" of data.
120 +Several of the changes are ‘breaking’ meaning that, in specific cases, the version 3.0 specification is not backwardly compatible with earlier versions of the Standard.
118 118  
119 -[[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] identifies a standard technique for modelling, expressing, and understanding the structure of this multi-dimensional "cube", allowing automated processing of data from a variety of sources. This approach is widely applicable across types of data and attempts to provide the simplest and most easily comprehensible technique that will support the exchange of this broad set of data and related metadata.
122 +The principle breaking changes are:
120 120  
121 -The term "metadata" is very broad indeed. A distinction can be made between “structural” metadata – those (% style="color:#e74c3c" %)concepts(%%) used in the description and identification of statistical data and metadata – and “reference” metadata – the larger set of (% style="color:#e74c3c" %)concepts(%%) that describe and qualify statistical [[data sets>>doc:sdmx:Glossary.Data set.WebHome]] and processing more generally, and which are often associated not with specific observations or series of data, but with entire collections of data or even the institutions which provide that data.
124 +* REST API – The REST API is not backwardly compatible due to modifications to the URLs and query parameters resulting in breaking changes in four of the five main resources.
125 +* SOAP API – Deprecation of the SOAP API means that existing systems designed to use SOAP will not work with version 3.0 registries.
126 +* SDMX-ML – SDMX 2.1 and earlier structure, data and metadata XML messages are not valid in version 3.0. Specifically: legacy data messages including Generic, Compact and Utility are no longer supported. The remaining Structure Specific data message has been changed to support new features such as reporting of reference metadata as part of the dataset, Structure messages have a number of breaking changes, principally modification to the information model, removal of the agency-version-id option for referencing artefacts and changes to the way the structures are organised into ‘collections’ within the message.
127 +* SDMX-JSON – SDMX 2.1 structure, data and metadata JSON messages are not valid in version 3.0. The data message has been changed to support the improved REST data queries, in particular the ability to retrieve in one operation data from multiple datasets with potentially different Data Structure Definitions. Breaking changes similar to those for the SDMX-ML transmission format have been made to the structure message.
128 +* SDMX-CSV - The CSV data and reference metadata messages are not backwardly compatible with those under version 2.1 due to changes to the structure of the messages needed to support new features such as the improved REST API data queries.
129 +* SDMX-EDI – Deprecation of the EDI transmission format means that existing systems designed to send or receive structures or data in EDI will not work with version 3.0 registries.
130 +* Information Model – Several structures have been changed in the version 3.0 model and three removed. For these reasons the version 3.0 model is not directly compatible with version 2.1 or earlier, although conversion of specific artefacts is possible under some circumstances. Loss of information during the conversion process however means that in cases like structure mapping, the conversion is not reversible i.e. it is not possible to recreate the 2.1 structure once it has been converted to the 3.0 model.
122 122  
123 -The [[SDMX Information Model>>doc:sdmx:Glossary.SDMX Information Model.WebHome]] provides for the structuring not only of data, but also of “reference” metadata. While these [[reference metadata>>doc:sdmx:Glossary.Reference metadata.WebHome]] structures exist independent of the data and its [[structural metadata>>doc:sdmx:Glossary.Structural metadata.WebHome]], they are often linked. The [[SDMX Information Model>>doc:sdmx:Glossary.SDMX Information Model.WebHome]] provides for the attachment of [[reference metadata>>doc:sdmx:Glossary.Reference metadata.WebHome]] to any part of the data or [[structural metadata>>doc:sdmx:Glossary.Structural metadata.WebHome]], as well as for the reporting and exchange of the [[reference metadata>>doc:sdmx:Glossary.Reference metadata.WebHome]] and its structural descriptions. This function of the [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] standards supports many aspects of data quality initiatives, allowing as it does for the exchange of metadata in its broadest sense, of which quality-related metadata is a major part.
132 +The SDMX 3.0 Major Changes document provides more information including an analysis of the breaking changes.
124 124  
125 -Metadata are associated not only with data, but also with the process of providing and managing the flow of data. The [[SDMX Information Model>>doc:sdmx:Glossary.SDMX Information Model.WebHome]] provides for a set of metadata concerned with “data provisioning” – metadata which are useful to those who need to understand the content and form of a [[data provider>>doc:sdmx:Glossary.Data provider.WebHome]]’s output. Each [[data provider>>doc:sdmx:Glossary.Data provider.WebHome]] can describe in standard fashion the content of and dependencies within the data and [[metadata sets>>doc:sdmx:Glossary.Metadata set.WebHome]] which they produce, and supply information about the scheduling and mechanism by which their data and metadata are provided. This allows for automation of some validation and control functions, as well as supporting management of data reporting.
134 +== 2.4 Major Changes from 3.0 to 3.1 ==
126 126  
127 -[[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] also recognizes the importance of classification schemes in organizing and managing the exchange and dissemination of data and metadata. It is possible to express information about classification schemes and domain [[categories>>doc:sdmx:Glossary.Category.WebHome]] in [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]], along with their relationships to data and [[metadata sets>>doc:sdmx:Glossary.Metadata set.WebHome]], as well as to categorize other objects in the model.
136 +(% class="wikigeneratedid" id="HInformationModel-1" %)
137 +**Information Model**
128 128  
129 -The [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] standards offer a common model, a choice of syntax and, for XML, a choice of data formats which support the exchange of any type of statistical data meeting the definition above; several optimized formats are specified based on the specific requirements of each implementation, as described below in the [[SDMX-ML>>doc:sdmx:Glossary.SDMX-ML.WebHome]] section.
139 +* Addition of Dimension Constraint property to a Dataflow//  //
140 +* Addition of evolving structure property to a Data Structure Definition//  //
141 +* Remove version property on Categorisation//  //
142 +* Simplification of Constraints o Removal of Advanced Release Calendar//  //
130 130  
131 -The formal objects in the information model are presented schematically in Figure 1, and are discussed in more detail elsewhere in this document.
144 +o Removal of Role, Data Constraints only restrict data that can be reported// //o Restrict constraint targets to Identifiable structures (not URLs) o Addition of Availability Constraint to define actual data
132 132  
133 -This document specifies the [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] standards designed to facilitate exchanges based on any of these process patterns, and shows how [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] offers advantages in all cases. It is possible to agree bilaterally to use a standard format (such as [[SDMX-ML>>doc:sdmx:Glossary.SDMX-ML.WebHome]] or [[SDMX-JSON>>doc:sdmx:Glossary.SDMX-JSON.WebHome]]); it is possible for data senders in a gateway process to use a standard format for data exchange with each other, or with any [[data providers>>doc:sdmx:Glossary.Data provider.WebHome]] who agree to do so; it is possible to agree to use the full set of [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] standards to support a common data-sharing process of exchange, whether based on an [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]]-conformant registry or some other architecture.
146 +(% class="wikigeneratedid" id="HDocumentation" %)
147 +**Documentation**
134 134  
135 -The standards specified here specifically support a data-sharing process based on the use of central registry services. Registry services provide visibility into the data and metadata existing within the community, and support the access and use of this data and metadata by providing a set of triggers for automated processing. The data or metadata itself is not stored in a central registry – these services merely provide a useful set of metadata about the data (and additional metadata) in a known location, so that users/applications can easily locate and obtain whatever data and/or metadata is registered. The use of standards for all data, metadata, and the registry services themselves is ubiquitous, permitting a high (% style="color:#e74c3c" %)level(%%) of automation within a data-sharing community.
149 +• Registering Reference Metadata removed from documentation, to align with XML Registration object which is unable to reference a Metadata Provision, and REST API which is unable to query for registered reference metadata sources.
136 136  
137 -It should be pointed out that these different process models are not mutually exclusive – a single system capable of expressing data and metadata in [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]]-conformant formats could support all three scenarios. Different standards may be applicable to different processes (for example, many registry services interfaces are used only in a data-sharing scenario) but all have a common basis in a shared information model.
151 += 3 Processes and Business Scope =
138 138  
139 -In addition to looking at collection and reporting, it is also important to consider the dissemination of data. Data and metadata – no matter how they are exchanged between counterparties in the process of their development and creation – are all eventually supplied to an end user of some type. Often, this is through specific applications inside of institutions. But more and more frequently, data and metadata are also published on websites in various formats. The dissemination of data and its accompanying metadata on the web is a focus of the [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] standards. Standards for statistical data and metadata allow improvements in the publication of data – it becomes more easily possible to process a standard format once the data is obtained, and the data and metadata are linked together, making the comprehension and further processing of the data easier.
153 +== 3.1 Process Patterns ==
140 140  
141 -In discussions of statistical data, there are many aspects of its dissemination which impact data quality: data discovery, ease of use, and [[timeliness>>doc:sdmx:Glossary.Timeliness.WebHome]]. [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] standards provide support for all of these aspects of data dissemination. Standard data formats promote ease of use, and provide links to relevant metadata. The (% style="color:#e74c3c" %)concept(%%) of registry services means that data and metadata can more easily be discovered. [[Timeliness>>doc:sdmx:Glossary.Timeliness.WebHome]] is improved throughout the data lifecycle by increases in efficiency, promoted through the availability of metadata and ease of use.
155 +SDMX identifies three basic process patterns regarding the exchange of statistical data and metadata. These can be described as follows:
142 142  
143 -It is important to note that [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] is primarily focused on the //exchange// and //dissemination// of statistical data and metadata. There may also be many uses for the standard model and formats specified here in the context of internal processing of data that are not concerned with the exchange between organizations and users, however. It is felt that a clear, standard formatting of data and metadata for the purposes of exchange and dissemination can also facilitate internal processing by organizations and users, but this is not the focus of the specification.
157 +1. //Bilateral exchange~:// All aspects of the exchange process are agreed between counterparties, including the mechanism for exchange of data and metadata, the formats, the frequency or schedule, and the mode used for communications regarding the exchange. This is perhaps the most common process pattern.
158 +1. //Gateway exchange~:// Gateway exchanges are an organized set of bilateral exchanges, in which several data and metadata collecting organizations or individuals agree to exchange the collected information with each other in a single, known format, and according to a single, known process. This pattern has the effect of reducing the burden of managing multiple bilateral exchanges (in data and metadata collection) across the sharing organizations/individuals. This is also a very common process pattern in the statistical area, where communities of institutions agree on ways to gain efficiencies within the scope of their collective responsibilities.
159 +1. //Data-sharing exchange~:// Open, freely available data formats and process patterns are known and standard. Thus, any organization or individual can use any counterparty’s data and metadata (assuming they are permitted access to it). This model requires no bilateral agreement, but only requires that data and metadata providers and consumers adhere to the standards.
144 144  
145 -== 3.2 SDMX and Process Automation ==
161 +This document specifies the SDMX standards designed to facilitate exchanges based on any of these process patterns, and shows how SDMX offers advantages in all cases. It is possible to agree bilaterally to use a standard format (such as SDMX-ML or SDMX-JSON); it is possible for data senders in a gateway process to use a standard format for data exchange with each other, or with any data providers who agree to do so; it is possible to agree to use the full set of SDMX standards to support a common data-sharing process of exchange, whether based on an SDMX-conformant registry or some other architecture.
146 146  
147 -Statistical data and metadata exchanges employ many different automated processes, but some are of more general interest than others. There are some common information technologies that are nearly ubiquitous within information systems today. [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] aims to provide standards that are most useful for these automated processes and technologies.
163 +The standards specified here specifically support a data-sharing process based on the use of central registry services. Registry services provide visibility into the data and metadata existing within the community, and support the access and use of this data and metadata by providing a set of triggers for automated processing. The data or metadata itself is not stored in a central registry – these services merely provide a useful set of metadata about the data (and additional metadata) in a known location, so that users/applications can easily locate and obtain whatever data and/or metadata is registered. The use of standards for all data, metadata, and the registry services themselves is ubiquitous, permitting a high level of automation within a data-sharing community.
148 148  
149 -Briefly, these can be described as:
165 +It should be pointed out that these different process models are not mutually exclusive – a single system capable of expressing data and metadata in SDMX-conformant formats could support all three scenarios. Different standards may be applicable to different processes (for example, many registry services interfaces are used only in a data-sharing scenario) but all have a common basis in a shared information model.
150 150  
151 -//Batch Exchange of Data and Metadata~:// The transmission of whole or partial databases between counterparties, including incremental updating. //Provision of Data and Metadata on the Internet~:// Internet technology - including its use in private or semi-private TCP/IP networks - is extremely common. This technology includes XML, JSON and REST web services as primary mechanisms for automating data and metadata provision, as well as the more traditional static HTML and database-driven publishing. //Generic Processes~:// While many applications and processes are specific to some set of data and metadata, other types of automated services and processes are designed to handle any type of statistical data and metadata whatsoever. This is particularly true in cases where portal sites and data feeds are made available on the Internet. //Presentation and Transformation of Data~:// In order to make data and metadata useful to consumers, they must support automated processes that transform them into application-specific processing formats, other standard formats, and presentational formats. Although not strictly an aspect of exchange, this type of automated processing represents a set of requirements that must be supported if the information exchange between counterparties is itself to be supported.
167 +In addition to looking at collection and reporting, it is also important to consider the dissemination of data. Data and metadata – no matter how they are exchanged between counterparties in the process of their development and creation – are all eventually supplied to an end user of some type. Often, this is through specific applications inside of institutions. But more and more frequently, data and metadata are also published on websites in various formats. The dissemination of data and its accompanying metadata on the web is a focus of the SDMX standards. Standards for statistical data and metadata allow improvements in the publication of data – it becomes more easily possible to process a standard format once the data is obtained, and the data and metadata are linked together, making the comprehension and further processing of the data easier.
152 152  
153 -o Removal of Role, Data (% style="color:#e74c3c" %)Constraints(%%) only restrict data that can be reported// //o Restrict (% style="color:#e74c3c" %)constraint(%%) targets to Identifiable structures (not URLs) o Addition of Availability (% style="color:#e74c3c" %)Constraint(%%) to define actual data
169 +In discussions of statistical data, there are many aspects of its dissemination which impact data quality: data discovery, ease of use, and timeliness. SDMX standards provide support for all of these aspects of data dissemination. Standard data formats promote ease of use, and provide links to relevant metadata. The concept of registry services means that data and metadata can more easily be discovered. Timeliness is improved throughout the data lifecycle by increases in efficiency, promoted through the availability of metadata and ease of use.
154 154  
155 -(% class="wikigeneratedid" id="HDocumentation" %)
156 -**Documentation**
171 +It is important to note that SDMX is primarily focused on the //exchange// and //dissemination// of statistical data and metadata. There may also be many uses for the standard model and formats specified here in the context of internal processing of data that are not concerned with the exchange between organizations and users, however. It is felt that a clear, standard formatting of data and metadata for the purposes of exchange and dissemination can also facilitate internal processing by organizations and users, but this is not the focus of the specification.
157 157  
158 -• Registering [[Reference Metadata>>doc:sdmx:Glossary.Reference metadata.WebHome]] removed from documentation, to align with XML Registration object which is unable to reference a Metadata Provision, and REST API which is unable to query for registered [[reference metadata>>doc:sdmx:Glossary.Reference metadata.WebHome]] sources.
173 +== 3.2 SDMX and Process Automation ==
159 159  
160 -= 3 Processes and Business Scope =
175 +Statistical data and metadata exchanges employ many different automated processes, but some are of more general interest than others. There are some common information technologies that are nearly ubiquitous within information systems today. SDMX aims to provide standards that are most useful for these automated processes and technologies.
161 161  
162 -== 3.1 Process Patterns ==
177 +Briefly, these can be described as:
163 163  
164 -[[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] identifies three basic process patterns regarding the exchange of statistical data and metadata. These can be described as follows:
179 +1. //Batch Exchange of Data and Metadata~:// The transmission of whole or partial databases between counterparties, including incremental updating.
180 +1. //Provision of Data and Metadata on the Internet~:// Internet technology - including its use in private or semi-private TCP/IP networks - is extremely common. This technology includes XML, JSON and REST web services as primary mechanisms for automating data and metadata provision, as well as the more traditional static HTML and database-driven publishing.
181 +1. //Generic Processes~:// While many applications and processes are specific to some set of data and metadata, other types of automated services and processes are designed to handle any type of statistical data and metadata whatsoever. This is particularly true in cases where portal sites and data feeds are made available on the Internet.
182 +1. //Presentation and Transformation of Data~:// In order to make data and metadata useful to consumers, they must support automated processes that transform them into application-specific processing formats, other standard formats, and presentational formats. Although not strictly an aspect of exchange, this type of automated processing represents a set of requirements that must be supported if the information exchange between counterparties is itself to be supported.
165 165  
166 -//Bilateral exchange~:// All aspects of the exchange process are agreed between counterparties, including the mechanism for exchange of data and metadata, the formats, the frequency or schedule, and the mode used for communications regarding the exchange. This is perhaps the most common process pattern. //Gateway exchange~:// Gateway exchanges are an organized set of bilateral exchanges, in which several data and metadata collecting organizations or individuals agree to exchange the collected information with each other in a single, known format, and according to a single, known process. This pattern has the effect of reducing the burden of managing multiple bilateral exchanges (in data and metadata collection) across the sharing organizations/individuals. This is also a very common process pattern in the statistical area, where communities of institutions agree on ways to gain efficiencies within the scope of their collective responsibilities. //Data-sharing exchange~:// Open, freely available data formats and process patterns are known and standard. Thus, any organization or individual can use any counterparty’s data and metadata (assuming they are permitted access to it). This model requires no bilateral agreement, but only requires that data and metadata providers and consumers adhere to the standards.
184 +The SDMX standards specified here are designed to support the requirements of all of these automation processes and technologies.
167 167  
168 -The [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] 3.0 Major Changes document provides more information including an analysis of the breaking changes.
186 +== 3.3 Statistical Data and Metadata ==
169 169  
170 -== 2.4 Major Changes from 3.0 to 3.1 ==
188 +To avoid confusion about which "data" and "metadata" are the intended content of the SDMX formats specified here, a statement of scope is offered. Statistical "data" are sets of often numeric observations which typically have time associated with them. They are associated with a set of metadata values, representing specific concepts, which act as identifiers and descriptors of the data. These metadata values and concepts can be understood as the named dimensions of a multi-dimensional co-ordinate system, describing what is often called a "cube" of data.
171 171  
172 -(% class="wikigeneratedid" id="HInformationModel-1" %)
173 -**Information Model**
190 +SDMX identifies a standard technique for modelling, expressing, and understanding the structure of this multi-dimensional "cube", allowing automated processing of data from a variety of sources. This approach is widely applicable across types of data and attempts to provide the simplest and most easily comprehensible technique that will support the exchange of this broad set of data and related metadata.
174 174  
175 -Addition of [[Dimension>>doc:sdmx:Glossary.Dimension.WebHome]] (% style="color:#e74c3c" %)Constraint(%%) property to a Dataflow Addition of evolving structure property to a Data Structure Definition Remove (% style="color:#e74c3c" %)version(%%) property on Categorisation Simplification of (% style="color:#e74c3c" %)Constraints(%%) o Removal of Advanced Release Calendar
192 +The term "metadata" is very broad indeed. A distinction can be made between “structural” metadata – those concepts used in the description and identification of statistical data and metadata – and “reference” metadata – the larger set of concepts that describe and qualify statistical data sets and processing more generally, and which are often associated not with specific observations or series of data, but with entire collections of data or even the institutions which provide that data.
176 176  
177 -Several of the changes are ‘breaking’ meaning that, in specific cases, the (% style="color:#e74c3c" %)version(%%) 3.0 specification is not backwardly compatible with earlier (% style="color:#e74c3c" %)versions(%%) of the Standard.
194 +The SDMX Information Model provides for the structuring not only of data, but also of “reference” metadata. While these reference metadata structures exist independent of the data and its structural metadata, they are often linked. The SDMX Information Model provides for the attachment of reference metadata to any part of the data or structural metadata, as well as for the reporting and exchange of the reference metadata and its structural descriptions. This function of the SDMX standards supports many aspects of data quality initiatives, allowing as it does for the exchange of metadata in its broadest sense, of which quality-related metadata is a major part.
178 178  
179 -The principle breaking changes are:
196 +Metadata are associated not only with data, but also with the process of providing and managing the flow of data. The SDMX Information Model provides for a set of metadata concerned with “data provisioning” – metadata which are useful to those who need to understand the content and form of a data provider’s output. Each data provider can describe in standard fashion the content of and dependencies within the data and metadata sets which they produce, and supply information about the scheduling and mechanism by which their data and metadata are provided. This allows for automation of some validation and control functions, as well as supporting management of data reporting.
180 180  
181 -REST API – The REST API is not backwardly compatible due to modifications to the URLs and query parameters resulting in breaking changes in four of the five main resources. SOAP API – Deprecation of the SOAP API means that existing systems designed to use SOAP will not work with (% style="color:#e74c3c" %)version(%%) 3.0 registries. [[SDMX-ML>>doc:sdmx:Glossary.SDMX-ML.WebHome]] – [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] 2.1 and earlier structure, data and metadata XML messages are not valid in (% style="color:#e74c3c" %)version(%%) 3.0. Specifically: legacy data messages including Generic, Compact and Utility are no longer supported. The remaining Structure Specific data message has been changed to support new features such as reporting of [[reference metadata>>doc:sdmx:Glossary.Reference metadata.WebHome]] as part of the [[dataset>>doc:sdmx:Glossary.Data set.WebHome]], Structure messages have a number of breaking changes, principally modification to the information model, removal of the agency-(% style="color:#e74c3c" %)version(%%)-id option for referencing [[artefacts>>doc:sdmx:Glossary.Artefact.WebHome]] and changes to the way the structures are organised into ‘collections’ within the message. [[SDMX-JSON>>doc:sdmx:Glossary.SDMX-JSON.WebHome]] – [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] 2.1 structure, data and metadata JSON messages are not valid in (% style="color:#e74c3c" %)version(%%) 3.0. The data message has been changed to support the improved REST data queries, in particular the ability to retrieve in one operation data from multiple [[datasets>>doc:sdmx:Glossary.Data set.WebHome]] with potentially different [[Data Structure Definitions>>doc:sdmx:Glossary.Data structure definition.WebHome]]. Breaking changes similar to those for the [[SDMX-ML>>doc:sdmx:Glossary.SDMX-ML.WebHome]] transmission format have been made to the structure message. [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]]-CSV - The CSV data and [[reference metadata>>doc:sdmx:Glossary.Reference metadata.WebHome]] messages are not backwardly compatible with those under (% style="color:#e74c3c" %)version(%%) 2.1 due to changes to the structure of the messages needed to support new features such as the improved REST API data queries. [[SDMX-EDI>>doc:sdmx:Glossary.SDMX-EDI.WebHome]] – Deprecation of the EDI transmission format means that existing systems designed to send or receive structures or data in EDI will not work with (% style="color:#e74c3c" %)version(%%) 3.0 registries. Information Model – Several structures have been changed in the (% style="color:#e74c3c" %)version(%%) 3.0 model and three removed. For these reasons the (% style="color:#e74c3c" %)version(%%) 3.0 model is not directly compatible with (% style="color:#e74c3c" %)version(%%) 2.1 or earlier, although conversion of specific [[artefacts>>doc:sdmx:Glossary.Artefact.WebHome]] is possible under some circumstances. Loss of information during the conversion process however means that in cases like structure mapping, the conversion is not reversible i.e. it is not possible to recreate the 2.1 structure once it has been converted to the 3.0 model.
198 +SDMX also recognizes the importance of classification schemes in organizing and managing the exchange and dissemination of data and metadata. It is possible to express information about classification schemes and domain categories in SDMX, along with their relationships to data and metadata sets, as well as to categorize other objects in the model.
182 182  
183 -(% class="wikigeneratedid" id="HSOAPWebServicesAPI" %)
184 -**SOAP Web Services API**
200 +The SDMX standards offer a common model, a choice of syntax and, for XML, a choice of data formats which support the exchange of any type of statistical data meeting the definition above; several optimized formats are specified based on the specific requirements of each implementation, as described below in the SDMX-ML section.
185 185  
186 -• The SOAP web services API has been deprecated with (% style="color:#e74c3c" %)version(%%) 3.0 standardising on REST
202 +The formal objects in the information model are presented schematically in Figure 1, and are discussed in more detail elsewhere in this document.
187 187  
188 -(% class="wikigeneratedid" id="HXML2CJSON2CCSVandEDITransmissionformats" %)
189 -**XML, JSON, CSV and EDI Transmission formats**
204 +[[image:SDMX_3-1-0_SECTION_1_FINAL_6728d8d4.png||height="829" width="606"]]
190 190  
191 -The [[SDMX-ML>>doc:sdmx:Glossary.SDMX-ML.WebHome]], [[SDMX-JSON>>doc:sdmx:Glossary.SDMX-JSON.WebHome]] and [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]]-CSV specifications have been extended and modified where needed to support the new features and changes such as [[reference metadata>>doc:sdmx:Glossary.Reference metadata.WebHome]] and microdata Obsolete [[SDMX-ML>>doc:sdmx:Glossary.SDMX-ML.WebHome]] data message variants including Generic, Compact, Utility and Cross-sectional have been deprecated standardising on Structure Specific Data as the sole XML format for data exchange The [[SDMX-EDI>>doc:sdmx:Glossary.SDMX-EDI.WebHome]] transmission format for structures and data has been deprecated The organisation of structures into ‘collections’ in [[SDMX-ML>>doc:sdmx:Glossary.SDMX-ML.WebHome]] and [[SDMX-JSON>>doc:sdmx:Glossary.SDMX-JSON.WebHome]] structure messages has been flattened and simplified The option to reference structures in [[SDMX-ML>>doc:sdmx:Glossary.SDMX-ML.WebHome]] and [[SDMX-JSON>>doc:sdmx:Glossary.SDMX-JSON.WebHome]] messages using Agency, ID and (% style="color:#e74c3c" %)Version(%%) has been deprecated with URN now exclusively used for all non-local referencing purpose
192 -
193 -[[image:SDMX 3.1 Section 1.png]]
194 -
195 195  **Figure 1: High Level Schematic of Major Artefacts in the SDMX 3.0 Information Model**
196 196  
197 197  == 3.4 The SDMX View of Statistical Exchange ==
198 198  
199 -(% style="color:#e74c3c" %)Version(%%) 1.0 of ISO/TS 17369 [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] covered statistical [[data sets>>doc:sdmx:Glossary.Data set.WebHome]] and the metadata related to the structure of these [[data sets>>doc:sdmx:Glossary.Data set.WebHome]]. This scope was useful in supporting the different models of statistical exchange (bilateral exchange, gateway exchange, and data-sharing) but was not by itself sufficient to support them completely. (% style="color:#e74c3c" %)Versions(%%) 2.0 and 2.1 provide a much more complete view of statistical exchange, so that an open data-sharing model can be fully supported, and other models of exchange can be more completely automated. In order to produce technical standards that will support this increased scope, the [[SDMX Information Model>>doc:sdmx:Glossary.SDMX Information Model.WebHome]] provides a broader set of formal objects which describe the actors, processes, and resources within statistical exchanges.
210 +Version 1.0 of ISO/TS 17369 SDMX covered statistical data sets and the metadata related to the structure of these data sets. This scope was useful in supporting the different models of statistical exchange (bilateral exchange, gateway exchange, and data-sharing) but was not by itself sufficient to support them completely. Versions 2.0 and 2.1 provide a much more complete view of statistical exchange, so that an open data-sharing model can be fully supported, and other models of exchange can be more completely automated. In order to produce technical standards that will support this increased scope, the SDMX Information Model provides a broader set of formal objects which describe the actors, processes, and resources within statistical exchanges.
200 200  
201 201  It is important to understand the set of formal objects not only in a technical sense, but also in terms of what they represent in the real-world exchange of statistical data and metadata.
202 202  
203 -The first (% style="color:#e74c3c" %)version(%%) of [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] provided for [[data sets>>doc:sdmx:Glossary.Data set.WebHome]] - specific statistical data reported according to a specific structure, for a specific time range - and for [[data structure definitions>>doc:sdmx:Glossary.Data structure definition.WebHome]] - the metadata which describes the structure of statistical [[data sets>>doc:sdmx:Glossary.Data set.WebHome]]. These are important objects in statistical exchanges, and are retained and enhanced in the second (% style="color:#e74c3c" %)version(%%) of the standards in a backward-compatible form. A related object in statistical exchanges is the "[[data flow>>doc:sdmx:Glossary.Dataflow.WebHome]]" - this supports the (% style="color:#e74c3c" %)concept(%%) of data reporting or dissemination on an ongoing basis. "[[Data flows>>doc:sdmx:Glossary.Dataflow.WebHome]]" can be understood as [[data sets>>doc:sdmx:Glossary.Data set.WebHome]] which are not bounded by time. Data structures are owned and maintained by agencies - in a similar fashion, [[data flows>>doc:sdmx:Glossary.Dataflow.WebHome]] are owned by maintenance agencies.
214 +The first version of SDMX provided for data sets - specific statistical data reported according to a specific structure, for a specific time range - and for data structure definitions - the metadata which describes the structure of statistical data sets. These are important objects in statistical exchanges, and are retained and enhanced in the second version of the standards in a backward-compatible form. A related object in statistical exchanges is the "data flow" - this supports the concept of data reporting or dissemination on an ongoing basis. "Data flows" can be understood as data sets which are not bounded by time. Data structures are owned and maintained by agencies - in a similar fashion, data flows are owned by maintenance agencies.
204 204  
205 -[[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] allows for the publication of statistical data (and the related [[structural metadata>>doc:sdmx:Glossary.Structural metadata.WebHome]]) but also provided for the standard, systematic [[representation>>doc:sdmx:Glossary.Representation.WebHome]] of [[reference metadata>>doc:sdmx:Glossary.Reference metadata.WebHome]]. In (% style="color:#e74c3c" %)version(%%) 2.1, [[reference metadata>>doc:sdmx:Glossary.Reference metadata.WebHome]] were reported independent of the statistical data. However, in 3.0 [[reference metadata>>doc:sdmx:Glossary.Reference metadata.WebHome]] associated directly with data such as footnotes are reported as [[attributes>>doc:sdmx:Glossary.Attribute.WebHome]] of the [[data set>>doc:sdmx:Glossary.Data set.WebHome]]. For other [[reference metadata>>doc:sdmx:Glossary.Reference metadata.WebHome]], principally that linked to structures like “(% style="color:#e74c3c" %)concepts(%%)”, [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] provides reference "[[metadata sets>>doc:sdmx:Glossary.Metadata set.WebHome]]", "[[metadata structure definitions>>doc:sdmx:Glossary.Metadata structure definition.WebHome]]", and "[[metadata flows>>doc:sdmx:Glossary.Metadataflow.WebHome]]". These objects are very similar to [[data sets>>doc:sdmx:Glossary.Data set.WebHome]], [[data structure definitions>>doc:sdmx:Glossary.Data structure definition.WebHome]], and [[data flows>>doc:sdmx:Glossary.Dataflow.WebHome]], but concern [[reference metadata>>doc:sdmx:Glossary.Reference metadata.WebHome]] rather than statistical observations. In the same way that [[data providers>>doc:sdmx:Glossary.Data provider.WebHome]] may publish statistical data, they may also publish [[reference metadata>>doc:sdmx:Glossary.Reference metadata.WebHome]]. Metadata structural definitions are maintained by agencies in a fashion similar to the way that agencies maintain [[data structure definitions>>doc:sdmx:Glossary.Data structure definition.WebHome]], the structural definitions of [[data sets>>doc:sdmx:Glossary.Data set.WebHome]].
216 +SDMX allows for the publication of statistical data (and the related structural metadata) but also provided for the standard, systematic representation of reference metadata. In version 2.1, reference metadata were reported independent of the statistical data. However, in 3.0 reference metadata associated directly with data such as footnotes are reported as attributes of the data set. For other reference metadata, principally that linked to structures like “concepts”, SDMX provides reference "metadata sets", "metadata structure definitions", and "metadata flows". These objects are very similar to data sets, data structure definitions, and data flows, but concern reference metadata rather than statistical observations. In the same way that data providers may publish statistical data, they may also publish reference metadata. Metadata structural definitions are maintained by agencies in a fashion similar to the way that agencies maintain data structure definitions, the structural definitions of data sets.
206 206  
207 -The structural definitions of both data and [[reference metadata>>doc:sdmx:Glossary.Reference metadata.WebHome]] associate specific statistical (% style="color:#e74c3c" %)concepts(%%) with their [[representations>>doc:sdmx:Glossary.Representation.WebHome]], whether textual, coded, etc. These (% style="color:#e74c3c" %)concepts(%%) are taken from a "[[concept scheme>>doc:sdmx:Glossary.Concept scheme.WebHome]]" which is maintained by a specific agency. [[Concept schemes>>doc:sdmx:Glossary.Concept scheme.WebHome]] group a set of (% style="color:#e74c3c" %)concepts(%%), provide their definitions and names, and allow for semantic relationships to be expressed, when some (% style="color:#e74c3c" %)concepts(%%) are specializations of others. It is possible for a single [[concept scheme>>doc:sdmx:Glossary.Concept scheme.WebHome]] to be used both for data structures - key families - and for [[reference metadata>>doc:sdmx:Glossary.Reference metadata.WebHome]] structures.
218 +The structural definitions of both data and reference metadata associate specific statistical concepts with their representations, whether textual, coded, etc. These concepts are taken from a "concept scheme" which is maintained by a specific agency. Concept schemes group a set of concepts, provide their definitions and names, and allow for semantic relationships to be expressed, when some concepts are specializations of others. It is possible for a single concept scheme to be used both for data structures - key families - and for reference metadata structures.
208 208  
209 -Inherent in any statistical exchange – and in many dissemination activities – is a (% style="color:#e74c3c" %)concept(%%) of "service (% style="color:#e74c3c" %)level(%%) agreement", even if this is not formalized or made explicit. [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] incorporates this idea in objects termed "[[provision agreements>>doc:sdmx:Glossary.Provision agreement.WebHome]]". [[Data providers>>doc:sdmx:Glossary.Data provider.WebHome]] may provide data to many different [[data flows>>doc:sdmx:Glossary.Dataflow.WebHome]]. [[Data flows>>doc:sdmx:Glossary.Dataflow.WebHome]] may incorporate data coming from more than one [[data provider>>doc:sdmx:Glossary.Data provider.WebHome]]. [[Provision agreements>>doc:sdmx:Glossary.Provision agreement.WebHome]] are the objects which tell you which [[data providers>>doc:sdmx:Glossary.Data provider.WebHome]] are supplying what data to which [[data flows>>doc:sdmx:Glossary.Dataflow.WebHome]]. Similarly, metadata [[provision agreements>>doc:sdmx:Glossary.Provision agreement.WebHome]] for [[metadata flows>>doc:sdmx:Glossary.Metadataflow.WebHome]].
220 +Inherent in any statistical exchange – and in many dissemination activities – is a concept of "service level agreement", even if this is not formalized or made explicit. SDMX incorporates this idea in objects termed "provision agreements". Data providers may provide data to many different data flows. Data flows may incorporate data coming from more than one data provider. Provision agreements are the objects which tell you which data providers are supplying what data to which data flows. Similarly, metadata provision agreements for metadata flows.
210 210  
211 -[[Provision Agreements>>doc:sdmx:Glossary.Provision agreement.WebHome]] allow for data collection restrictions to be applied at the (% style="color:#e74c3c" %)level(%%) of the [[Data Provider>>doc:sdmx:Glossary.Data provider.WebHome]] in the context of the collection ([[data flow>>doc:sdmx:Glossary.Dataflow.WebHome]]), this set of information is termed a ‘Data (% style="color:#e74c3c" %)Constraint(%%)’ in the [[SDMX Information Model>>doc:sdmx:Glossary.SDMX Information Model.WebHome]]. Additionally, in a dissemination environment, data can be queried at the (% style="color:#e74c3c" %)level(%%) of the [[Provision Agreement>>doc:sdmx:Glossary.Provision agreement.WebHome]], this can be a complete [[dataset>>doc:sdmx:Glossary.Data set.WebHome]] as supplied by a specific [[Data Provider>>doc:sdmx:Glossary.Data provider.WebHome]] for the [[Dataflow>>doc:sdmx:Glossary.Dataflow.WebHome]], a subset of data, or information about what data exists (Data Availability).
222 +Provision Agreements allow for data collection restrictions to be applied at the level of the Data Provider in the context of the collection (data flow), this set of information is termed a ‘Data Constraint’ in the SDMX Information Model. Additionally, in a dissemination environment, data can be queried at the level of the Provision Agreement, this can be a complete dataset as supplied by a specific Data Provider for the Dataflow, a subset of data, or information about what data exists (Data Availability).
212 212  
213 213  A brief summary of the objects described in the information model includes:
214 214  
215 -* //**[[Data Set>>doc:sdmx:Glossary.Data set.WebHome]]:**// Data is organized into discrete sets, which include particular observations for a specific period of time. A [[data set>>doc:sdmx:Glossary.Data set.WebHome]] can be understood as a collection of similar data, sharing a structure, which covers a fixed period of time.
216 -* //**[[Data Structure Definition>>doc:sdmx:Glossary.Data structure definition.WebHome]] ([[DSD>>doc:sdmx:Glossary.Data structure definition.WebHome]], also known as Key Family in (% style="color:#e74c3c" %)Version(%%) 2.0): **//Each [[data set>>doc:sdmx:Glossary.Data set.WebHome]] has a set of [[structural metadata>>doc:sdmx:Glossary.Structural metadata.WebHome]]. These descriptions are referred to in [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] as [[Data Structure Definitions>>doc:sdmx:Glossary.Data structure definition.WebHome]], which include information about how (% style="color:#e74c3c" %)concepts(%%) are associated with the [[measures>>doc:sdmx:Glossary.Measure.WebHome]], [[dimensions>>doc:sdmx:Glossary.Dimension.WebHome]], and [[attributes>>doc:sdmx:Glossary.Attribute.WebHome]] of a data “cube,” along with information about the [[representation>>doc:sdmx:Glossary.Representation.WebHome]] of data and related identifying and descriptive (structural) metadata. In (% style="color:#e74c3c" %)Version(%%) 2.1, the term "Key Family" was replaced by "[[Data Structure Definition>>doc:sdmx:Glossary.Data structure definition.WebHome]]" ([[DSD>>doc:sdmx:Glossary.Data structure definition.WebHome]]) both in XML Schemas and the Information Model. The [[DSD>>doc:sdmx:Glossary.Data structure definition.WebHome]] has been modified in (% style="color:#e74c3c" %)version(%%) 3.0 to better support microdata by providing the option to define multiple [[measures>>doc:sdmx:Glossary.Measure.WebHome]] and for [[attributes>>doc:sdmx:Glossary.Attribute.WebHome]] and [[measures>>doc:sdmx:Glossary.Measure.WebHome]] to take arrays of values. An optional reference to a [[Metadata Structure Definition>>doc:sdmx:Glossary.Metadata structure definition.WebHome]] has also been added for describing the [[reference metadata>>doc:sdmx:Glossary.Reference metadata.WebHome]] associated with the data. When reported, these [[reference metadata>>doc:sdmx:Glossary.Reference metadata.WebHome]] are included as part of the [[dataset>>doc:sdmx:Glossary.Data set.WebHome]].
217 -* //**[[Code list>>doc:sdmx:Glossary.Code list.WebHome]]:**// [[Code lists>>doc:sdmx:Glossary.Code list.WebHome]] enumerate a set of [[codes>>doc:sdmx:Glossary.Code.WebHome]] to be used in the [[representation>>doc:sdmx:Glossary.Representation.WebHome]] of [[dimensions>>doc:sdmx:Glossary.Dimension.WebHome]], [[attributes>>doc:sdmx:Glossary.Attribute.WebHome]], and other structural parts of [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]]. [[Codes>>doc:sdmx:Glossary.Code.WebHome]] can be organised into simple [[hierarchies>>doc:sdmx:Glossary.Hierarchy.WebHome]] within a [[code list>>doc:sdmx:Glossary.Code list.WebHome]], and more complex [[hierarchies>>doc:sdmx:Glossary.Hierarchy.WebHome]] potentially involving multiple [[code lists>>doc:sdmx:Glossary.Code list.WebHome]] using [[hierarchy>>doc:sdmx:Glossary.Hierarchy.WebHome]] and [[hierarchy>>doc:sdmx:Glossary.Hierarchy.WebHome]] association structures.
218 -* //**Value list:**// Value lists introduced in (% style="color:#e74c3c" %)version(%%) 3.0 are similar to codelists with the exception that the items do not need to conform to the usual [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] rules for identifiable objects. That allows the values to include characters such as [[currency>>doc:sdmx:Glossary.Currency.WebHome]] symbols (e.g. ¥) which would otherwise make illegal [[codes>>doc:sdmx:Glossary.Code.WebHome]]. However, unlike [[codes>>doc:sdmx:Glossary.Code.WebHome]], values are not individually identifiable. Value lists find application in (% style="color:#e74c3c" %)concepts(%%) and [[data structures definitions>>doc:sdmx:Glossary.Data structure definition.WebHome]] for less structured data and microdata enumerations and can be (% style="color:#e74c3c" %)mapped(%%) to other value or [[code lists>>doc:sdmx:Glossary.Code list.WebHome]] using [[representation>>doc:sdmx:Glossary.Representation.WebHome]] (% style="color:#e74c3c" %)maps(%%).
219 -* //**Organisation Scheme:**// Organisations and organisation structure can be defined in an Organisation Scheme. Specific Organisation Schemes exist for [[Maintenance Agency>>doc:sdmx:Glossary.Maintenance agency.WebHome]], [[Data Provider>>doc:sdmx:Glossary.Data provider.WebHome]], Metadata Provider, [[Data Consumer>>doc:sdmx:Glossary.Data consumer.WebHome]], and Organisation Unit.
220 -* //**[[Category Scheme>>doc:sdmx:Glossary.Category scheme.WebHome]] and Categorisation:**// [[Category schemes>>doc:sdmx:Glossary.Category scheme.WebHome]] are made up of a [[hierarchy>>doc:sdmx:Glossary.Hierarchy.WebHome]] of [[categories>>doc:sdmx:Glossary.Category.WebHome]], which in [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] may include any type of useful classification for the organization of data and metadata. A Categorisation links a [[category>>doc:sdmx:Glossary.Category.WebHome]] to an identifiable object. In this way sets of objects can be categorised. A statistical subjectmatter domain scheme is implemented in [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] as a [[Category Scheme>>doc:sdmx:Glossary.Category scheme.WebHome]].
221 -* //**[[Concept Scheme>>doc:sdmx:Glossary.Concept scheme.WebHome]]:**// A [[concept scheme>>doc:sdmx:Glossary.Concept scheme.WebHome]] is a maintained list of (% style="color:#e74c3c" %)concepts(%%) that are used in [[data structure definitions>>doc:sdmx:Glossary.Data structure definition.WebHome]] and [[metadata structure definitions>>doc:sdmx:Glossary.Metadata structure definition.WebHome]]. There can be many such [[concept schemes>>doc:sdmx:Glossary.Concept scheme.WebHome]]. A “core” [[representation>>doc:sdmx:Glossary.Representation.WebHome]] of the (% style="color:#e74c3c" %)concept(%%) can be specified (e.g. a core [[code list>>doc:sdmx:Glossary.Code list.WebHome]], or other [[representation>>doc:sdmx:Glossary.Representation.WebHome]] such as “date”). Note that this core [[representation>>doc:sdmx:Glossary.Representation.WebHome]] can be overridden in the [[data structure definition>>doc:sdmx:Glossary.Data structure definition.WebHome]] or [[metadata structure definition>>doc:sdmx:Glossary.Metadata structure definition.WebHome]] that uses the (% style="color:#e74c3c" %)concept(%%). Indeed, organisations wishing to remain with (% style="color:#e74c3c" %)version(%%) 1.0 key family schema specifications will continue to declare the [[representation>>doc:sdmx:Glossary.Representation.WebHome]] in the key family definition.
222 -* //**[[Metadata Set>>doc:sdmx:Glossary.Metadata set.WebHome]]:**// A [[reference metadata>>doc:sdmx:Glossary.Reference metadata.WebHome]] set is a set of information pertaining to an object within the formal [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] view of statistical exchange: they may describe the maintainers of data or structural definitions; they may describe the schedule on which data is released; they may describe the flow of a single type of data over time; they may describe the quality of data, etc. In [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]], the creators of [[reference metadata>>doc:sdmx:Glossary.Reference metadata.WebHome]] may take whatever (% style="color:#e74c3c" %)concepts(%%) they are concerned with, or obliged to report, and provide a [[reference metadata>>doc:sdmx:Glossary.Reference metadata.WebHome]] set containing that information.
223 -* //**[[Metadata Structure Definition>>doc:sdmx:Glossary.Metadata structure definition.WebHome]]:**// A [[reference metadata>>doc:sdmx:Glossary.Reference metadata.WebHome]] set also has a set of [[structural metadata>>doc:sdmx:Glossary.Structural metadata.WebHome]] which describes how it is organized. This [[metadata set>>doc:sdmx:Glossary.Metadata set.WebHome]] identifies what [[reference metadata>>doc:sdmx:Glossary.Reference metadata.WebHome]] (% style="color:#e74c3c" %)concepts(%%) are being reported, how these (% style="color:#e74c3c" %)concepts(%%) relate to each other (typically as [[hierarchies>>doc:sdmx:Glossary.Hierarchy.WebHome]]), what their presentational structure is, how they may be represented (as free text, as coded values, etc.), and with which formal [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] object types they are associated.
224 -* //**[[Dataflow>>doc:sdmx:Glossary.Dataflow.WebHome]] Definition:**// In [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]], [[data sets>>doc:sdmx:Glossary.Data set.WebHome]] are reported or disseminated according to a [[data flow>>doc:sdmx:Glossary.Dataflow.WebHome]] definition. The [[data flow>>doc:sdmx:Glossary.Dataflow.WebHome]] definition identifies the [[data structure definition>>doc:sdmx:Glossary.Data structure definition.WebHome]] and may be associated with one or more subject matter domains via a Categorisation (this facilitates the search for data according to organised [[category schemes>>doc:sdmx:Glossary.Category scheme.WebHome]]). (% style="color:#e74c3c" %)Constraints(%%), in terms of reporting periodicity or sub set of possible keys that are allowed in a [[data set>>doc:sdmx:Glossary.Data set.WebHome]], may be attached to the [[data flow>>doc:sdmx:Glossary.Dataflow.WebHome]] definition.
225 -* //**Metadataflow Definition:**// A [[metadata flow>>doc:sdmx:Glossary.Metadataflow.WebHome]] definition is very similar to a [[data flow>>doc:sdmx:Glossary.Dataflow.WebHome]] definition, but describes, categorises, and constrains [[metadata sets>>doc:sdmx:Glossary.Metadata set.WebHome]].
226 -* //**[[Data Provider>>doc:sdmx:Glossary.Data provider.WebHome]]: **//An organization which produces data is termed a [[data provider>>doc:sdmx:Glossary.Data provider.WebHome]].
227 -* //**Metadata Provider: **//An organization which produces [[reference metadata>>doc:sdmx:Glossary.Reference metadata.WebHome]] is termed a metadata provider.
228 -* //**[[Provision Agreement>>doc:sdmx:Glossary.Provision agreement.WebHome]] (Metadata [[Provision Agreement>>doc:sdmx:Glossary.Provision agreement.WebHome]]):**// The set of information which describes the way in which [[data sets>>doc:sdmx:Glossary.Data set.WebHome]] and [[metadata sets>>doc:sdmx:Glossary.Metadata set.WebHome]] are provided by a data/metadata provider. A [[provision agreement>>doc:sdmx:Glossary.Provision agreement.WebHome]] can be constrained in much the same way as a data or [[metadata flow>>doc:sdmx:Glossary.Metadataflow.WebHome]] definition. Thus, a [[data provider>>doc:sdmx:Glossary.Data provider.WebHome]] can express the fact that it provides a particular [[data flow>>doc:sdmx:Glossary.Dataflow.WebHome]] covering a specific set of countries and topics, Importantly, the actual source of registered data or metadata is attached to the [[provision agreement>>doc:sdmx:Glossary.Provision agreement.WebHome]] (in terms of a URL). The term “agreement” is used because this information can be understood as the basis of a “service-(% style="color:#e74c3c" %)level(%%) agreement”. In [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]], however, this is informational metadata to support the technical systems, as opposed to any sort of contractual information (which is outside the scope of a technical specification). In (% style="color:#e74c3c" %)version(%%) 3.0, metadata [[provision agreement>>doc:sdmx:Glossary.Provision agreement.WebHome]] and data [[provision agreement>>doc:sdmx:Glossary.Provision agreement.WebHome]] are two separate artefacts.
229 -* //**Data (% style="color:#e74c3c" %)Constraint(%%):**// Used to restrict content (such as enumerations) and are used by [[provision agreements>>doc:sdmx:Glossary.Provision agreement.WebHome]], [[data flows>>doc:sdmx:Glossary.Dataflow.WebHome]], [[data structure definitions>>doc:sdmx:Glossary.Data structure definition.WebHome]] in order to provide a set of reporting restrictions in the context of a collection
230 -* //**Metadata (% style="color:#e74c3c" %)Constraint(%%):**// Used to restrict content (such as enumerations) and are used by metadata [[provision agreements>>doc:sdmx:Glossary.Provision agreement.WebHome]], [[metadata flows>>doc:sdmx:Glossary.Metadataflow.WebHome]], [[metadata structure definitions>>doc:sdmx:Glossary.Metadata structure definition.WebHome]] in order to provide a set of reporting restrictions in the context of a collection
231 -* • //**Available Data (% style="color:#e74c3c" %)Constraint(%%):**// Used to report the set of [[Component>>doc:sdmx:Glossary.Component.WebHome]] values that have data reported against them in the context of a Data Query. This structure allows a user to know what valid filters can be applied to a cube of data, such that the resulting cube will contain data.
232 -* • //**Structure (% style="color:#e74c3c" %)Map(%%): **//Structure (% style="color:#e74c3c" %)maps(%%) describes a mapping between [[data structure definitions>>doc:sdmx:Glossary.Data structure definition.WebHome]] or [[dataflows>>doc:sdmx:Glossary.Dataflow.WebHome]] for the purpose of transforming a [[data set>>doc:sdmx:Glossary.Data set.WebHome]] into a different structure. The mapping rules are defined using one or more [[component>>doc:sdmx:Glossary.Component.WebHome]] (% style="color:#e74c3c" %)maps(%%) which each (% style="color:#e74c3c" %)map(%%) in turn describes how one or more [[components>>doc:sdmx:Glossary.Component.WebHome]] from the source [[data structure definition>>doc:sdmx:Glossary.Data structure definition.WebHome]] (% style="color:#e74c3c" %)map(%%) to one or more [[components>>doc:sdmx:Glossary.Component.WebHome]] in that of the target. Represent (% style="color:#e74c3c" %)maps(%%) act as lookup tables and specific provision is made for mapping dates and times.
233 -* • //**[[Representation>>doc:sdmx:Glossary.Representation.WebHome]] (% style="color:#e74c3c" %)Map(%%):**// [[Representation>>doc:sdmx:Glossary.Representation.WebHome]] (% style="color:#e74c3c" %)maps(%%) describe mappings between source value(s) and target value(s) where the values are restricted to those in a [[code list>>doc:sdmx:Glossary.Code list.WebHome]], value list or be of a certain type such as integer or string.
234 -* • //**[[Item Scheme>>doc:sdmx:Glossary.Item scheme.WebHome]] (% style="color:#e74c3c" %)Map(%%):**// An [[item scheme>>doc:sdmx:Glossary.Item scheme.WebHome]] (% style="color:#e74c3c" %)map(%%) describes mapping rules between any [[item scheme>>doc:sdmx:Glossary.Item scheme.WebHome]] with the exception of [[code lists>>doc:sdmx:Glossary.Code list.WebHome]] and value lists which use [[representation>>doc:sdmx:Glossary.Representation.WebHome]] (% style="color:#e74c3c" %)maps(%%). The (% style="color:#e74c3c" %)version(%%) 3.0 information model provides four [[item scheme>>doc:sdmx:Glossary.Item scheme.WebHome]] (% style="color:#e74c3c" %)maps(%%): organisation scheme (% style="color:#e74c3c" %)map(%%), [[concept scheme>>doc:sdmx:Glossary.Concept scheme.WebHome]] (% style="color:#e74c3c" %)map(%%), [[category scheme>>doc:sdmx:Glossary.Category scheme.WebHome]] (% style="color:#e74c3c" %)map(%%) and [[reporting taxonomy>>doc:sdmx:Glossary.Reporting taxonomy.WebHome]] (% style="color:#e74c3c" %)map(%%). Organisation scheme (% style="color:#e74c3c" %)map(%%) and reporting scheme (% style="color:#e74c3c" %)map(%%) have been omitted from the information model schematic in Figure 1.
235 -* • //**[[Reporting Taxonomy>>doc:sdmx:Glossary.Reporting taxonomy.WebHome]]: **//A [[reporting taxonomy>>doc:sdmx:Glossary.Reporting taxonomy.WebHome]] allows an organisation to link (possibly in a hierarchical way) a number of cube or [[data flow>>doc:sdmx:Glossary.Dataflow.WebHome]] definitions which together form a complete “report” of data or metadata. This supports primary reporting which often comprises multiple cubes of heterogeneous data, but may also support other collection and reporting functions. It also supports the specification of publications such as a yearbook, in terms of the data or metadata contained in the publication.
236 -* • //**Process:**// The process class provides a way to model statistical processes as a set of interconnected //process steps.// Although not central to the exchange and dissemination of statistical data and metadata, having a shared description of processing allows for the interoperable exchange and dissemination of [[reference metadata>>doc:sdmx:Glossary.Reference metadata.WebHome]] sets which describe processes-related (% style="color:#e74c3c" %)concepts(%%).
237 -* • //**[[Hierarchy>>doc:sdmx:Glossary.Hierarchy.WebHome]]**//: Describes complex [[code>>doc:sdmx:Glossary.Code.WebHome]] [[hierarchies>>doc:sdmx:Glossary.Hierarchy.WebHome]] principally for data discovery purposes. The [[codes>>doc:sdmx:Glossary.Code.WebHome]] themselves are referenced from the [[code lists>>doc:sdmx:Glossary.Code list.WebHome]] in which they are maintained.
238 -* • //**[[Hierarchy>>doc:sdmx:Glossary.Hierarchy.WebHome]] Association**//: A [[hierarchy>>doc:sdmx:Glossary.Hierarchy.WebHome]] association links a [[hierarchy>>doc:sdmx:Glossary.Hierarchy.WebHome]] to something that needs it like a [[dimension>>doc:sdmx:Glossary.Dimension.WebHome]]. Furthermore, the linking can be specified in the context of another object such as a [[dimension>>doc:sdmx:Glossary.Dimension.WebHome]] in the context of a [[dataflow>>doc:sdmx:Glossary.Dataflow.WebHome]]. Thus, a [[dimension>>doc:sdmx:Glossary.Dimension.WebHome]] in a [[data structure definition>>doc:sdmx:Glossary.Data structure definition.WebHome]] could have different [[hierarchies>>doc:sdmx:Glossary.Hierarchy.WebHome]] depending on the [[dataflow>>doc:sdmx:Glossary.Dataflow.WebHome]].
239 -* • //**Transformation Scheme:**// A transformation scheme is a set of [[Validation and Transformation Language>>doc:sdmx:Glossary.Validation and transformation language.WebHome]] ([[VTL>>doc:sdmx:Glossary.Validation and transformation language.WebHome]]) transformations aimed at obtaining some meaningful results for the user (e.g., the validation of one or more [[data sets>>doc:sdmx:Glossary.Data set.WebHome]]). The set of transformations is meant to be executed together (in the same run) and may contain 597 any number of transformations in order to produce any number of results. Thus, a transformation scheme can be considered as a [[VTL>>doc:sdmx:Glossary.Validation and transformation language.WebHome]] ‘program’.
226 +* //**Data Set:**// Data is organized into discrete sets, which include particular observations for a specific period of time. A data set can be understood as a collection of similar data, sharing a structure, which covers a fixed period of time.
227 +* //**Data Structure Definition (DSD, also known as Key Family in Version 2.0): **//Each data set has a set of structural metadata. These descriptions are referred to in SDMX as Data Structure Definitions, which include information about how concepts are associated with the measures, dimensions, and attributes of a data “cube,” along with information about the representation of data and related identifying and descriptive (structural) metadata. In Version 2.1, the term "Key Family" was replaced by "Data Structure Definition" (DSD) both in XML Schemas and the Information Model. The DSD has been modified in version 3.0 to better support microdata by providing the option to define multiple measures and for attributes and measures to take arrays of values. An optional reference to a Metadata Structure Definition has also been added for describing the reference metadata associated with the data. When reported, these reference metadata are included as part of the dataset.
228 +* //**Code list:**// Code lists enumerate a set of codes to be used in the representation of dimensions, attributes, and other structural parts of SDMX. Codes can be organised into simple hierarchies within a code list, and more complex hierarchies potentially involving multiple code lists using hierarchy and hierarchy association structures.
229 +* //**Value list:**// Value lists introduced in version 3.0 are similar to codelists with the exception that the items do not need to conform to the usual SDMX rules for identifiable objects. That allows the values to include characters such as currency symbols (e.g. ¥) which would otherwise make illegal codes. However, unlike codes, values are not individually identifiable. Value lists find application in concepts and data structures definitions for less structured data and microdata enumerations and can be mapped to other value or code lists using representation maps.
230 +* //**Organisation Scheme:**// Organisations and organisation structure can be defined in an Organisation Scheme. Specific Organisation Schemes exist for Maintenance Agency, Data Provider, Metadata Provider, Data Consumer, and Organisation Unit.
231 +* //**Category Scheme and Categorisation:**// Category schemes are made up of a hierarchy of categories, which in SDMX may include any type of useful classification for the organization of data and metadata. A Categorisation links a category to an identifiable object. In this way sets of objects can be categorised. A statistical subjectmatter domain scheme is implemented in SDMX as a Category Scheme.
232 +* //**Concept Scheme:**// A concept scheme is a maintained list of concepts that are used in data structure definitions and metadata structure definitions. There can be many such concept schemes. A “core” representation of the concept can be specified (e.g. a core code list, or other representation such as “date”). Note that this core representation can be overridden in the data structure definition or metadata structure definition that uses the concept. Indeed, organisations wishing to remain with version 1.0 key family schema specifications will continue to declare the representation in the key family definition.
233 +* //**Metadata Set:**// A reference metadata set is a set of information pertaining to an object within the formal SDMX view of statistical exchange: they may describe the maintainers of data or structural definitions; they may describe the schedule on which data is released; they may describe the flow of a single type of data over time; they may describe the quality of data, etc. In SDMX, the creators of reference metadata may take whatever concepts they are concerned with, or obliged to report, and provide a reference metadata set containing that information.
234 +* //**Metadata Structure Definition:**// A reference metadata set also has a set of structural metadata which describes how it is organized. This metadata set identifies what reference metadata concepts are being reported, how these concepts relate to each other (typically as hierarchies), what their presentational structure is, how they may be represented (as free text, as coded values, etc.), and with which formal SDMX object types they are associated.
235 +* //**Dataflow Definition:**// In SDMX, data sets are reported or disseminated according to a data flow definition. The data flow definition identifies the data structure definition and may be associated with one or more subject matter domains via a Categorisation (this facilitates the search for data according to organised category schemes). Constraints, in terms of reporting periodicity or sub set of possible keys that are allowed in a data set, may be attached to the data flow definition.
236 +* //**Metadataflow Definition:**// A metadata flow definition is very similar to a data flow definition, but describes, categorises, and constrains metadata sets.
237 +* //**Data Provider: **//An organization which produces data is termed a data provider.
238 +* //**Metadata Provider: **//An organization which produces reference metadata is termed a metadata provider.//  //
239 +* //**Provision Agreement (Metadata Provision Agreement):**// The set of information which describes the way in which data sets and metadata sets are provided by a data/metadata provider. A provision agreement can be constrained in much the same way as a data or metadata flow definition. Thus, a data provider can express the fact that it provides a particular data flow covering a specific set of countries and topics, Importantly, the actual source of registered data or metadata is attached to the provision agreement (in terms of a URL). The term “agreement” is used because this information can be understood as the basis of a “service-level agreement”. In SDMX, however, this is informational metadata to support the technical systems, as opposed to any sort of contractual information (which is outside the scope of a technical specification). In version 3.0, metadata provision agreement and data provision agreement are two separate artefacts.
240 +* //**Data Constraint:**// Used to restrict content (such as enumerations) and are used by provision agreements, data flows, data structure definitions in order to provide a set of reporting restrictions in the context of a collection
241 +* //**Metadata Constraint:**// Used to restrict content (such as enumerations) and are used by metadata provision agreements, metadata flows, metadata structure definitions in order to provide a set of reporting restrictions in the context of a collection
240 240  
243 +• //**Available Data Constraint:**// Used to report the set of Component values that have data reported against them in the context of a Data Query. This structure allows a user to know what valid filters can be applied to a cube of data, such that the resulting cube will contain data.
244 +
245 +• //**Structure Map: **//Structure maps describes a mapping between data structure definitions or dataflows for the purpose of transforming a data set into a different structure. The mapping rules are defined using one or more component maps which each map in turn describes how one or more components from the source data structure definition map to one or more components in that of the target. Represent maps act as lookup tables and specific provision is made for mapping dates and times.
246 +
247 +• //**Representation Map:**// Representation maps describe mappings between source value(s) and target value(s) where the values are restricted to those in a code list, value list or be of a certain type such as integer or string.
248 +
249 +• //**Item Scheme Map:**// An item scheme map describes mapping rules between any item scheme with the exception of code lists and value lists which use representation maps. The version 3.0 information model provides four item scheme maps: organisation scheme map, concept scheme map, category scheme map and reporting taxonomy map. Organisation scheme map and reporting scheme map have been omitted from the information model schematic in Figure 1.
250 +
251 +• //**Reporting Taxonomy: **//A reporting taxonomy allows an organisation to link (possibly in a hierarchical way) a number of cube or data flow definitions which together form a complete “report” of data or metadata. This supports primary reporting which often comprises multiple cubes of heterogeneous data, but may also support other collection and reporting functions. It also supports the specification of publications such as a yearbook, in terms of the data or metadata contained in the publication.
252 +
253 +• //**Process:**// The process class provides a way to model statistical processes as a set of interconnected //process steps.// Although not central to the exchange and dissemination of statistical data and metadata, having a shared description of processing allows for the interoperable exchange and dissemination of reference metadata sets which describe processes-related concepts.
254 +
255 +• //**Hierarchy**//: Describes complex code hierarchies principally for data discovery purposes. The codes themselves are referenced from the code lists in which they are maintained.
256 +
257 +• //**Hierarchy Association**//: A hierarchy association links a hierarchy to something that needs it like a dimension. Furthermore, the linking can be specified in the context of another object such as a dimension in the context of a dataflow. Thus, a dimension in a data structure definition could have different hierarchies depending on the dataflow.
258 +
259 +• //**Transformation Scheme:**// A transformation scheme is a set of Validation and Transformation Language (VTL) transformations aimed at obtaining some meaningful results for the user (e.g., the validation of one or more data sets). The set of transformations is meant to be executed together (in the same run) and may contain 597 any number of transformations in order to produce any number of results. Thus, a transformation scheme can be considered as a VTL ‘program’.
260 +
241 241  == 3.5 SDMX Registry Services ==
242 242  
243 -In order to provide visibility into the large amount of data and metadata which exists within the [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] model of statistical exchange, it is felt that an architecture based on a set of registry services is potentially useful. A “registry” – as understood in webservices terminology – is an application which maintains and stores metadata for querying, and which can be used by any other application in the network with sufficient access privileges (though note that the mechanism of access control is outside of the scope of the [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] standard). It can be understood as the index of a distributed database or [[metadata repository>>doc:sdmx:Glossary.Metadata repository.WebHome]] which is made up of all the [[data provider>>doc:sdmx:Glossary.Data provider.WebHome]]’s [[data sets>>doc:sdmx:Glossary.Data set.WebHome]] and [[reference metadata>>doc:sdmx:Glossary.Reference metadata.WebHome]] sets within a statistical community, located across the Internet or similar network.
263 +In order to provide visibility into the large amount of data and metadata which exists within the SDMX model of statistical exchange, it is felt that an architecture based on a set of registry services is potentially useful. A “registry” – as understood in webservices terminology – is an application which maintains and stores metadata for querying, and which can be used by any other application in the network with sufficient access privileges (though note that the mechanism of access control is outside of the scope of the SDMX standard). It can be understood as the index of a distributed database or metadata repository which is made up of all the data provider’s data sets and reference metadata sets within a statistical community, located across the Internet or similar network.
244 244  
245 -Note that the [[SDMX registry>>doc:sdmx:Glossary.SDMX Registry.WebHome]] services are not concerned with the storage of data or [[reference metadata>>doc:sdmx:Glossary.Reference metadata.WebHome]]. The assumption is that data and [[reference metadata>>doc:sdmx:Glossary.Reference metadata.WebHome]] lives on the sites of its data and metadata providers. The [[SDMX registry>>doc:sdmx:Glossary.SDMX Registry.WebHome]] services concern themselves with providing visibility of the data and [[reference metadata>>doc:sdmx:Glossary.Reference metadata.WebHome]], and information needed to access the data and [[reference metadata>>doc:sdmx:Glossary.Reference metadata.WebHome]]. Thus, a registered [[data set>>doc:sdmx:Glossary.Data set.WebHome]] will have its URL available in the registry, but not the data itself. An application which wishes to access that data would query the registry, perhaps by drilling down via a [[Category Scheme>>doc:sdmx:Glossary.Category scheme.WebHome]] and [[Dataflow>>doc:sdmx:Glossary.Dataflow.WebHome]], for the URL of a registered [[data source>>doc:sdmx:Glossary.Data source.WebHome]], and then retrieve the data directly from the [[data provider>>doc:sdmx:Glossary.Data provider.WebHome]] (using an [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] REST API query message or other mechanism).
265 +Note that the SDMX registry services are not concerned with the storage of data or reference metadata. The assumption is that data and reference metadata lives on the sites of its data and metadata providers. The SDMX registry services concern themselves with providing visibility of the data and reference metadata, and information needed to access the data and reference metadata. Thus, a registered data set will have its URL available in the registry, but not the data itself. An application which wishes to access that data would query the registry, perhaps by drilling down via a Category Scheme and Dataflow, for the URL of a registered data source, and then retrieve the data directly from the data provider (using an SDMX REST API query message or other mechanism).
246 246  
247 -[[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] does not require a particular technology implementation of the registry – instead, it specifies the standard interfaces which may be supported by a registry. Thus, users may implement an [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]]-conformant registry in any fashion they choose, provided the interfaces are supported as specified in Section 5 on the Registry Specification. These interfaces are expressed as XML documents, but also REST API request/response messages
267 +SDMX does not require a particular technology implementation of the registry – instead, it specifies the standard interfaces which may be supported by a registry. Thus, users may implement an SDMX-conformant registry in any fashion they choose, provided the interfaces are supported as specified in Section 5 on the Registry Specification. These interfaces are expressed as XML documents, but also REST API request/response messages
248 248  
249 249  The registry services discussed here can be briefly summarized:
250 250  
251 -* //**Maintenance of [[Structural Metadata>>doc:sdmx:Glossary.Structural metadata.WebHome]]**//**:** This registry service allows users with [[maintenance agency>>doc:sdmx:Glossary.Maintenance agency.WebHome]] access privileges to submit and modify [[structural metadata>>doc:sdmx:Glossary.Structural metadata.WebHome]]. In this aspect the registry is acting as a [[structural metadata>>doc:sdmx:Glossary.Structural metadata.WebHome]] repository. However, it is permissible in an [[SDMX>>doc:sdmx:Glossary.Statistical data and metadata exchange.WebHome]] structure to submit just the “stub” of the structural object, such as a [[code list>>doc:sdmx:Glossary.Code list.WebHome]], and for this stub to reference the actual location from where the metadata can be retrieved, either from a file or a [[structural metadata>>doc:sdmx:Glossary.Structural metadata.WebHome]] resource, such as another registry.
252 -* //**Registration of [[Data Sources>>doc:sdmx:Glossary.Data source.WebHome]]: **//This registry service allows users with [[maintenance agency>>doc:sdmx:Glossary.Maintenance agency.WebHome]] access privileges to inform the registry of the existence and location (for retrieval) of [[data sets>>doc:sdmx:Glossary.Data set.WebHome]] and [[reference metadata>>doc:sdmx:Glossary.Reference metadata.WebHome]] sets. The registry stores metadata about these objects, and links it to the [[structural metadata>>doc:sdmx:Glossary.Structural metadata.WebHome]] that give sufficient structural information for an application to process it, or for an application to discover its existence. Objects in the registry are organized and categorized according to one or more [[category schemes>>doc:sdmx:Glossary.Category scheme.WebHome]].
253 -* //**Querying: **//The registry services have interfaces for querying the metadata contained in a registry, so that applications and users can discover the existence of [[data sets>>doc:sdmx:Glossary.Data set.WebHome]] and [[reference metadata>>doc:sdmx:Glossary.Reference metadata.WebHome]] sets, [[structural metadata>>doc:sdmx:Glossary.Structural metadata.WebHome]], the providers/agencies associated with those objects, and the provider agreements which describe how the data and metadata are made available, and how they are categorized.
254 -* //**Subscription/[[Notification>>doc:sdmx:Glossary.Notification.WebHome]]:**// It is possible to “subscribe” to specific objects in a registry, so that a [[notification>>doc:sdmx:Glossary.Notification.WebHome]] will be sent to all subscribers whenever the registry objects are updated.
271 +* //**Maintenance of Structural Metadata**//**:** This registry service allows users with maintenance agency access privileges to submit and modify structural metadata. In this aspect the registry is acting as a structural metadata repository. However, it is permissible in an SDMX structure to submit just the “stub” of the structural object, such as a code list, and for this stub to reference the actual location from where the metadata can be retrieved, either from a file or a structural metadata resource, such as another registry.
272 +* //**Registration of Data Sources: **//This registry service allows users with maintenance agency access privileges to inform the registry of the existence and location (for retrieval) of data sets and reference metadata sets. The registry stores metadata about these objects, and links it to the structural metadata that give sufficient structural information for an application to process it, or for an application to discover its existence. Objects in the registry are organized and categorized according to one or more category schemes.
273 +* //**Querying: **//The registry services have interfaces for querying the metadata contained in a registry, so that applications and users can discover the existence of data sets and reference metadata sets, structural metadata, the providers/agencies associated with those objects, and the provider agreements which describe how the data and metadata are made available, and how they are categorized.
274 +* //**Subscription/Notification:**// It is possible to “subscribe” to specific objects in a registry, so that a notification will be sent to all subscribers whenever the registry objects are updated.
255 255  
256 256  == 3.6 RESTful Web services ==
257 257  
258 258  Web services allow computer applications to exchange data directly over the Internet, essentially allowing modular or distributed computing in a more flexible fashion than ever before. In order to allow web services to function, however, many standards are required: for requesting and supplying data; for expressing the enveloping data which is used to package exchanged data; for describing web services to one another, to allow for easy integration into applications that use other web services as data resources.
259 259  
260 -Version 3.1 has standardized on RESTful web services with a OpenAPI specification published on the SDMX Technical Working Group’s GitHub repository [[__https:~~/~~/github.com/sdmx-twg__>>https://https:github.comsdmx-twg]]. There are five ‘resources’:
280 +Version 3.1 has standardized on RESTful web services with a OpenAPI specification published on the SDMX Technical Working Group’s GitHub repository __[[https:~~/~~/github.com/sdmx>>url:https://github.com/sdmx-twg]][[->>url:https://github.com/sdmx-twg]][[twg>>url:https://github.com/sdmx-twg]]__[[.>>url:https://github.com/sdmx-twg]] There are five ‘resources’:
261 261  
262 262  * structure – retrieval and maintenance of structural metadata
263 263  * data – retrieval of data
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