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Summary

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Title
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1 -Notes on Data Structuring
1 +SDMX 2.1 Standards. Section 1. Framework for SDMX technical standards
Content
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1 -Revision History
1 +{{box title="**Contents**"}}
2 +{{toc/}}
3 +{{/box}}
2 2  
3 -|**Revision**|**Date**|**Contents**
4 -||April 2011|Initial release
5 -|1.0|July 2020|(((
6 -Added the last two sentences of the Section 1 – Introduction
5 +**Revision History**
7 7  
8 -Added the Section 10 –Validation and Transformation Language (VTL)
7 +(% style="width:808.294px" %)
8 +|(% style="width:154px" %)**Revision**|(% style="width:118px" %)**Date**|(% style="width:533px" %)**Contents**
9 +|(% style="width:154px" %) |(% style="width:118px" %)April 2011|(% style="width:533px" %)Initial release
10 +|(% style="width:154px" %)1.0|(% style="width:118px" %)July 2020|(% style="width:533px" %)(((
11 +Added the last two sentences of the Section 1 – Introduction
12 +Added the Section 10 –Validation and Transformation Language (VTL(% style="background-color:transparent" %))
9 9  )))
10 10  
11 -1. (((
12 -= {{id name="_Toc38908"/}}Introduction =
13 -)))
15 += {{id name="_Toc38908"/}}1. Introduction =
14 14  
15 15  The Statistical Data and Metadata Exchange (SDMX) initiative (http:~/~/www.sdmx.org) sets standards that can facilitate the exchange of statistical data and metadata using modern information technology, with an emphasis on aggregated data.
16 16  
... ... @@ -22,15 +22,13 @@
22 22  1. SDMX-ML - the XML format for the exchange of SDMX-structured data and metadata. This document has normative sections describing the use of the XML syntax in SDMX messages, and is accompanied by a set of normative XML schemas and non-normative sample XML document instances.
23 23  1. The SDMX Registry Specification provides for a central registry of information about available data and reference metadata, and for a repository containing structural metadata and provisioning information. This specification defines the basic services offered by the SDMX Registry: registration of data and metadata; querying for data and metadata; and subscription/notification regarding updates to the registry. This document has normative sections.
24 24  1. The SDMX Technical Notes – this is a guide to help those who wish to use the SDMX specifications. It includes notes on the expressive differences of the various messages and syntaxes; versioning; maintenance agencies; the SDMX Registry. This document is not normative.
25 -1. Web Services Guidelines – this is a guide for those who wish to implement SDMX using web-services technologies. It places an emphasis on those aspects of web-services technologies (including, but not requiring, an SDMXconformant registry) which will work regardless of the development environment or platform used to create the web services. This document contains normative sections.^^[[^^1^^>>path:#sdfootnote1sym||name="sdfootnote1anc"]]^^
27 +1. Web Services Guidelines – this is a guide for those who wish to implement SDMX using web-services technologies. It places an emphasis on those aspects of web-services technologies (including, but not requiring, an SDMXconformant registry) which will work regardless of the development environment or platform used to create the web services. This document contains normative sections.{{footnote}}SOAP and REST specifications are not maintained any more in this section, see the SDMX website.{{/footnote}}
26 26  
27 27  In July 2020 it was released an important improvement of the SDMX 2.1 specifications for the SDMX implementation of the Validation and Transformation Language (VTL). This implied a revision of some of the SDMX 2.1 sections. The relevant changes are not described in the next section but in the section 10 below.
28 28  
29 -Please note also that the SOAP and REST specifications are not maintained any more in the section 7 (Web Service Guidelines), the link to these specifications can be found on the SDMX website.
31 +Please note also that the SOAP and REST specifications are not maintained any more in the section 7 (Web Service Guidelines), the link to these specifications can be found on the SDMX website
30 30  
31 -1. (((
32 -= {{id name="_Toc38909"/}}Changes from Previous Version =
33 -)))
33 += {{id name="_Toc38909"/}}2. Changes from Previous Version =
34 34  
35 35  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.
36 36  
... ... @@ -42,46 +42,26 @@
42 42  
43 43  * **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.
44 44  * **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.
45 -* **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 98 lists are supported; relationships between data structures can be expressed, 99 providing support for extensibility of data structures; and the description of 100 functional dependencies within cubes are supported.
45 +* **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.
46 46  
47 47  The major changes from 2.0 to 2.1 can be briefly summarized:
48 48  
49 -**Web-Services-Oriented Changes:** Several organizations have been implementing web services applications using SDMX, and these 106 implementations have resulted in several changes to the specifications.
49 +* **Web-Services-Oriented Changes:** Several organizations have been implementing web services applications using SDMX, and these 106 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.
50 +* **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.
51 +* **Consistency Issues:** There have been some areas where the draft specifications were inconsistent in minor ways, and these have been addressed.
52 +* **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.
53 +* **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 object-oriented features of W3C XML Schema to allow for easier processing of SDMX data and metadata.
54 +* **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.
55 +* **Technical Bugs:** Some minor technical bugs have been identified in the registry interfaces and elsewhere. These bugs have been addressed.
56 +* **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.
57 +* **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.
58 +* **Simplification and better support for the metadata structure: **New use 140 cases have been reported and these are now supported by a re-modelled metadata structure definition.
59 +* **Support for partial item schemes such as a code list: **The concept of a 143 partial (sub-set) item scheme such as a partial code list for use in exchange scenarios has been introduced**.**
50 50  
51 -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.
61 += {{id name="_Toc38910"/}}3. Processes and Business Scope =
52 52  
53 -**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.** **
63 +== {{id name="_Toc38911"/}}3.1 Process Patterns ==
54 54  
55 -**Consistency Issues:** There have been some areas where the draft specifications were inconsistent in minor ways, and these have been addressed.
56 -
57 -**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.** **
58 -
59 -**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 object-oriented features of W3C XML Schema to allow for easier processing of SDMX data and metadata.** **
60 -
61 -**Consistency between the SDMX-ML and the SDMX Information Model:**
62 -
63 -Certain aspects of the XML schemas and UML model have been more closely aligned, to allow for easier comprehension of the SDMX model.
64 -
65 -**Technical Bugs:** Some minor technical bugs have been identified in the registry interfaces and elsewhere. These bugs have been addressed.
66 -
67 -**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.** **
68 -
69 -**Simplification of the data structure definition - specific message types:**
70 -
71 -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.
72 -
73 -**Simplification and better support for the metadata structure: **New use 140 cases have been reported and these are now supported by a re-modelled metadata structure definition.
74 -
75 -**Support for partial item schemes such as a code list: **The concept of a 143 partial (sub-set) item scheme such as a partial code list for use in exchange scenarios has been introduced**.**
76 -
77 -1. (((
78 -= {{id name="_Toc38910"/}}Processes and Business Scope =
79 -
80 -1. (((
81 -== {{id name="_Toc38911"/}}Process Patterns ==
82 -)))
83 -)))
84 -
85 85  SDMX identifies three basic process patterns regarding the exchange of statistical data and metadata. These can be described as follows:
86 86  
87 87  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.
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100 100  
101 101  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.
102 102  
103 -1.
104 -11. (((
105 -== {{id name="_Toc38912"/}}SDMX and Process Automation ==
106 -)))
83 +== {{id name="_Toc38912"/}}3.2 SDMX and Process Automation ==
107 107  
108 108  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.
109 109  
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116 116  
117 117  The SDMX standards specified here are designed to support the requirements of all of these automation processes and technologies.
118 118  
119 -1.
120 -11. (((
121 -== {{id name="_Toc38913"/}}Statistical Data and Metadata ==
122 -)))
96 +== {{id name="_Toc38913"/}}3.3 Statistical Data and Metadata ==
123 123  
124 124  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.
125 125  
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141 141  
142 142   **Figure 1: High Level Schematic of Major Artefacts in the SDMX Information Model**
143 143  
144 -1.
145 -11. (((
146 -== {{id name="_Toc38914"/}}The SDMX View of Statistical Exchange ==
147 -)))
118 +== {{id name="_Toc38914"/}}3.4 The SDMX View of Statistical Exchange ==
148 148  
149 149  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.
150 150  
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200 200  
201 201  As with data structures, the generic format for metadata sets provides a known document structure, whilst the structure specific format is derived specifically from a metadata structure definition and can perform a higher degree of schema validation.
202 202  
203 -1.
204 -11. (((
205 -== {{id name="_Toc38915"/}}SDMX Registry Services ==
206 -)))
174 +== {{id name="_Toc38915"/}}3.5 SDMX Registry Services ==
207 207  
208 208  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.
209 209  
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218 218  * //**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.
219 219  * //**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.
220 220  
221 -1.
222 -11. (((
223 -== {{id name="_Toc38916"/}}Web services ==
224 -)))
189 +== {{id name="_Toc38916"/}}3.6 Web services ==
225 225  
226 226  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.
227 227  
... ... @@ -234,9 +234,7 @@
234 234  
235 235  A normative list of common error codes: When web services are used, it is necessary to have error codes which can help to explain the situation when problems are encountered. Prior to version 2.1 of the SDMX standard, there was no set of agreed error codes for use with SDMX web services. Version 2.1 of the SDMX standard fills that gap.
236 236  
237 -1. (((
238 -= {{id name="_Toc38917"/}}The SDMX Information Model =
239 -)))
202 += {{id name="_Toc38917"/}}4 The SDMX Information Model =
240 240  
241 241  SDMX provides a way of modelling statistical data, and defines the set of metadata constructs used for this purpose. Because SDMX specifies formats in two syntaxes for expressing data and structural metadata, the model is used as a mechanism for guaranteeing that transformation between the different formats are lossless. All of the formats are syntax-bound expressions of the common information model. SDMX version 1.0 has based itself on GESMES/TS as an input to the model and formats, both to build on the proven success of this model for time series data exchange, and to ensure backward compatibility with existing GESMES/TS-based systems. Version 2.0/2.1 expands upon the version 1.0 basis to provide a more comprehensive model.
242 242  
... ... @@ -252,9 +252,7 @@
252 252  
253 253  The SDMX Information Model is presented using UML, and is also described in prose. While the information model is not normative, it is a valuable tool for understanding and using the normative format specifications.
254 254  
255 -1. (((
256 -= {{id name="_Toc38918"/}}SDMX-EDI =
257 -)))
218 += {{id name="_Toc38918"/}}5 SDMX-EDI =
258 258  
259 259  The SDMX-EDI format is drawn from the GESMES/TS version 3.0 implementation guide, as published as a standard of the SDMX initiative.
260 260  
... ... @@ -266,9 +266,7 @@
266 266  
267 267  EDIFACT syntax used for SDMX-EDI, and those found in the XML syntax of SDMXML. Since both syntactic implementations reflect the same logical constructs, SDMXEDI data and structural metadata messages can be transformed into corresponding SDMX-ML formats, and vice-versa. Thus, these standards provide for interoperability between the UN/EDIFACT-based and XML-based systems processing and exchanging statistical data and metadata.
268 268  
269 -1. (((
270 -= {{id name="_Toc38919"/}}SDMX-ML =
271 -)))
230 += {{id name="_Toc38919"/}}6 SDMX-ML =
272 272  
273 273  While the SDMX-EDI format is primarily designed to support batch exchange, SDMXML supports a wider range of requirements. XML formats are used for many different types of automated processing, and thus must support more varied processing scenarios. That is why there are several types of messages available as SDMX-ML formats. Each is suited to support a specific set of processing requirements.
274 274  
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285 285  
286 286  Because all of the SDMX-ML formats are implementations of the same information model, and all the data and metadata messages are derivable from the Structure message which describes a data set or metadata set, it is possible to have standard mappings between each of the similar formats. These mappings can be implemented in generic transformation tools, useful to all SDMX-ML users, and not specific to a particular data set’s key family or metadata set’s structure definition (even though some of the formats they deal with may be). Part of the SDMX-ML package is the set of mappings between the structure-specific data and metadata formats and the Structure Definition format from which all are derivable.
287 287  
288 -1. (((
289 -= {{id name="_Toc38920"/}}Conformance =
290 -)))
247 += {{id name="_Toc38920"/}}7 Conformance =
291 291  
292 292  This section will contain a normative statement of what applications must do to be considered conformant with the SDMX version 2.1 specifications. This will address both the application functionality that must be supported, and the contents of an Implementer’s Conformance Statement regarding SDMX conformance.
293 293  
294 -1. (((
295 -= {{id name="_Toc38921"/}}Dependencies on SDMX content-oriented guidelines =
296 -)))
251 += {{id name="_Toc38921"/}}8 Dependencies on SDMX content-oriented guidelines =
297 297  
298 298  The technical standards proposed here are designed so that they can be used in conjunction with other SDMX guidelines which are more closely tied to the content and semantics of statistical data exchange. The SDMX Information Model works equally well with any statistical concept, but to encourage interoperability, it is also necessary to standardize and harmonize the use of specific concepts and terminology. To achieve this goal, SDMX creates and maintains guidelines for crossdomain concepts, terminology, and structural definitions. There are three major parts to this effort.
299 299  
300 -1.
301 -11. (((
302 -== {{id name="_Toc38922"/}}Cross-Domain Concepts ==
303 -)))
255 +== {{id name="_Toc38922"/}}8.1 Cross-Domain Concepts ==
304 304  
305 305  The SDMX Cross-Domain Concepts is a content guideline concerning concepts which are used across statistical domains. This list is expected to grow and to be subject to revision as SDMX is used in a growing number of domains. The use of the SDMX Cross-Domain Concepts, where appropriate, provides a framework to further promote interoperability among organisations using the technical standards presented here. The harmonization of statistical concepts includes not only the definitions of the concepts, and their names, but also, where appropriate, their representation with standard code lists, and the role they play within data structure definitions and metadata structure definitions.
306 306  
307 307  The intent of this guideline is two-fold: to provide a core set of concepts which can be used to structure statistical data and metadata, to promote interoperability between systems (“structural metadata”, as described above); and to promote the exchange of metadata more widely, with a set of harmonized concept names and definitions for other types of metadata (“reference metadata”, as defined above.)
308 308  
309 -1.
310 -11. (((
311 -== {{id name="_Toc38923"/}}Metadata Common Vocabulary ==
312 -)))
261 +== {{id name="_Toc38923"/}}8.2 Metadata Common Vocabulary ==
313 313  
314 314  The Metadata Common Vocabulary is an SDMX guideline which provides definition of terms to be used for the comparison and mapping of terminology found in data structure definitions and in other aspects of statistical metadata management. Essentially, it provides ISO-compliant definitions for a wide range of statistical terms, which may be used directly, or against which other terminology systems may be mapped. This set of terms is inclusive of the terminology used within the SDMX Technical Standards.
315 315  
316 316  The MCV provides definitions for terms on which the SDMX Cross-Domain Metadata Concepts work is built.
317 317  
318 -1.
319 -11. (((
320 -== {{id name="_Toc38924"/}}Statistical Subject-Matter Domains ==
321 -)))
267 +== {{id name="_Toc38924"/}}8.3 Statistical Subject-Matter Domains ==
322 322  
323 323  The Statistical Subject-Matter Domains is a listing of the breadth of statistical information for the purposes of organizing widespread statistical exchange and categorization. It acts as a standard scheme against which the categorization schemes of various counterparties can be mapped, to facilitate interoperable data and metadata exchange. It serves another useful purpose, however, which is to allow an organization of corresponding “domain groups”, each of which could define standard data structure definitions, concepts, etc. within their domains. Such groups already exist within the international community. SDMX would use the Statistical Subject-Matter Domains list to facilitate the efforts of these groups to develop the kinds of content standards which could support the interoperation of SDMXconformant technical systems within and across statistical domains. The organisation of the content of such schemes is supported in SDMX as a Category Scheme.
324 324  
325 325  SDMX Statistical Subject-Matter Domains will be listed and maintained by the SDMX Initiative and will be subject to adjustment.
326 326  
327 -1. (((
328 -= {{id name="_Toc38925"/}}Looking Forward =
329 -)))
273 += {{id name="_Toc38925"/}}9 Looking Forward =
330 330  
331 331  The SDMX initiative sees this set of data and metadata formats and registry services interfaces standards as useful in creating more efficient and open systems for statistical exchange. It is anticipated that SDMX will refine these standards further as they are implemented, so as to build on the interoperability enabled by having a set of standard formats and exchanges based on a common information model.
332 332  
333 333  The review process for version 2.0 and 2.1 has suggested that future work should take advantage of a wider participation of the SDMX user community (statistical offices, central banks and other national and international organisations dealing with statistics) in further enhancing the Technical Standards and improving its use.
334 334  
335 -1. (((
336 -= {{id name="_Toc38926"/}}Validation and Transformation Language =
337 -)))
279 += {{id name="_Toc38926"/}}10 Validation and Transformation Language =
338 338  
339 339  For many years the SDMX initiative has been fostering and supporting the development of a standard calculation language, called Validation and Transformation Language (VTL). A blueprint for defining calculations was already described in the original SDMX 2.1 specifications (package 13 of the Information
340 340  
... ... @@ -360,4 +360,6 @@
360 360  
361 361  Finally, new REST interfaces for VTL have been added. These are not maintained any more in the section 7; the link to these specifications can be found on the SDMX website.
362 362  
363 -[[1>>path:#sdfootnote1anc||name="sdfootnote1sym"]] SOAP and REST specifications are not maintained any more in this section, see the SDMX website.
305 +----
306 +
307 +{{putFootnotes/}}