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10 10  
11 11  = 1 Introduction =
12 12  
13 -The [[Statistical Data and Metadata Exchange>>doc:sdmx:Glossary 2\.1.Statistical data and metadata exchange.WebHome]] ([[SDMX>>doc:sdmx:Glossary 2\.1.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>>https://https:www.sdmx.org||rel="noopener noreferrer" target="_blank"]]) 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 2\.1.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 2\.1.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||rel="noopener noreferrer" target="_blank"]]):
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 2\.1.SDMX Information Model.WebHome]] is a standardised object model for modelling [[statistical domains>>doc:sdmx:Glossary 2\.1.Statistical subject-matter domain.WebHome]] centring on the structure of their data and [[metadata sets>>doc:sdmx:Glossary 2\.1.Metadata set.WebHome]], the coding schemes used for [[classification>>doc:sdmx:Glossary 2\.1.Statistical Classification.WebHome]], 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 2\.1.Statistical data and metadata exchange.WebHome]] ‘registry’ acts as a repository for [[structural metadata>>doc:sdmx:Glossary 2\.1.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 2\.1.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 2\.1.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||rel="noopener noreferrer" target="_blank"]]): sdmx-twg/sdmx-rest – REST API
28 28  
29 -Technical specifications for the [[SDMX>>doc:sdmx:Glossary 2\.1.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 2\.1.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 2\.1.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-CSV>>doc:sdmx:Glossary 2\.1.SDMX-CSV.WebHome]] transmission format for ‘comma-separated values’ (CSV) data and [[reference metadata>>doc:sdmx:Glossary 2\.1.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 2\.1.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-EDI>>doc:sdmx:Glossary 2\.1.SDMX-EDI.WebHome]]
47 +Section 4 - SDMX-EDI
48 48  
49 -Section 7 - API - replaced by the sdmx-twg/sdmx-rest GitHub repository [[VTL>>doc:sdmx:Glossary 2\.1.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 2\.1.Statistical data and metadata exchange.WebHome]] 2.1 specifications were revised to add support for the [[Validation and Transformation Language>>doc:sdmx:Glossary 2\.1.Validation and transformation language.WebHome]] ([[VTL>>doc:sdmx:Glossary 2\.1.Validation and transformation language.WebHome]]). For 3.0, the [[VTL>>doc:sdmx:Glossary 2\.1.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 2\.1.Structural metadata.WebHome]] [[artefacts>>doc:sdmx:Glossary 2\.1.Artefact.WebHome]]. Section 2 (Information Model) sets out details of the ‘Transformation and Expressions’ package for defining and managing [[VTL>>doc:sdmx:Glossary 2\.1.Validation and transformation language.WebHome]] 2.0 programs and Section 6 (Technical Notes) provides detailed guidance on implementing and using [[VTL>>doc:sdmx:Glossary 2\.1.Validation and transformation language.WebHome]] with [[SDMX>>doc:sdmx:Glossary 2\.1.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 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 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 2\.1.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 2\.1.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 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 2\.1.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 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 2\.1.Reference metadata.WebHome]]**: In addition to describing and specifying data structures and formats (along with related [[structural metadata>>doc:sdmx:Glossary 2\.1.Structural metadata.WebHome]]), the version 2.0 specification also provides for the exchange of metadata which is distinct from the [[structural metadata>>doc:sdmx:Glossary 2\.1.Structural metadata.WebHome]] in the 1.0 version. This [[category>>doc:sdmx:Glossary 2\.1.Category.WebHome]] 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>>doc:sdmx:Glossary 2\.1.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 Registry>>doc:sdmx:Glossary 2\.1.SDMX Registry.WebHome]]**: 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 2\.1.Subscription.WebHome]]/[[notification>>doc:sdmx:Glossary 2\.1.Notification.WebHome]].
67 -* **[[Structural Metadata>>doc:sdmx:Glossary 2\.1.Structural metadata.WebHome]]**: The support for exchange of statistical data and related [[structural metadata>>doc:sdmx:Glossary 2\.1.Structural metadata.WebHome]] has been expanded. Some support is provided for qualitative data; data cube structures are described; [[hierarchical code lists>>doc:sdmx:Glossary 2\.1.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  
... ... @@ -98,7 +98,7 @@
98 98  (% class="wikigeneratedid" id="HVersioningofStructuralMetadataArtefacts" %)
99 99  **Versioning of Structural Metadata Artefacts**
100 100  
101 -Adoption of the three-number semantic versioning standard for [[structural metadata>>doc:sdmx:Glossary 2\.1.Structural metadata.WebHome]] [[artefacts>>doc:sdmx:Glossary 2\.1.Artefact.WebHome]] ([[__https:~~/~~/semver.org__>>https://https:semver.org]])
101 +Adoption of the three-number semantic versioning standard for [[structural metadata>>doc:sdmx:Glossary 2\.1.Structural metadata.WebHome]] [[artefacts>>doc:sdmx:Glossary 2\.1.Artefact.WebHome]] ([[__https:~~/~~/semver.org__>>https://https:semver.org||rel="noopener noreferrer" target="_blank"]])
102 102  
103 103  (% class="wikigeneratedid" id="HRESTWebServicesApplicationProgrammingInterface28API29" %)
104 104  **REST Web Services Application Programming Interface (API)**
... ... @@ -273,7 +273,7 @@
273 273  
274 274  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.
275 275  
276 -Version 3.1 has standardized on RESTful web services with a OpenAPI specification published on the [[SDMX>>doc:sdmx:Glossary 2\.1.Statistical data and metadata exchange.WebHome]] Technical Working Group’s GitHub repository  [[__https:~~/~~/github.com/sdmx-twg__>>https://https:github.comsdmx-twg]].
276 +Version 3.1 has standardized on RESTful web services with a OpenAPI specification published on the [[SDMX>>doc:sdmx:Glossary 2\.1.Statistical data and metadata exchange.WebHome]] Technical Working Group’s GitHub repository  [[__https:~~/~~/github.com/sdmx-twg__>>https://https:github.comsdmx-twg||rel="noopener noreferrer" target="_blank"]].
277 277  
278 278  There are five ‘resources’:
279 279  
... ... @@ -284,7 +284,7 @@
284 284  * metadata – retrieval of [[reference metadata>>doc:sdmx:Glossary 2\.1.Reference metadata.WebHome]]
285 285  * registration – retrieval of data locations (URL) for specific [[provision agreements>>doc:sdmx:Glossary 2\.1.Provision agreement.WebHome]]
286 286  
287 -The following conceptual example uses the ‘data’ resource to query a data repository for a [[series>>doc:sdmx:Glossary 2\.1.Series.WebHome]] identified by the key ‘M.USD.EUR.SP00.A’ in the EXR (ECB exchange rates) [[Dataflow>>doc:sdmx:Glossary 2\.1.Dataflow.WebHome]]: https:~/~/ws-entry-point/data/dataflow/ECB/EXR/1.0.0/M.USD.EUR.SP00.A
287 +The following conceptual example uses the ‘data’ resource to query a data repository for a [[series>>doc:sdmx:Glossary 2\.1.Series.WebHome]] identified by the key ‘M.USD.EUR.SP00.A’ in the EXR (ECB exchange rates) [[Dataflow>>doc:sdmx:Glossary 2\.1.Dataflow.WebHome]]: [[https:~~/~~/ws-entry-point/data/dataflow/ECB/EXR/1.0.0/M.USD.EUR.SP00.A>>https://https:ws-entry-pointdatadataflowECBEXR1.0.0M.USD.EUR.SP00.A]]
288 288  
289 289  = 4 The SDMX Information Model =
290 290  
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