Wiki source code of 10 Constraints

Version 14.6 by Helena on 2025/05/16 12:24

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2.1	4
	5	== 10.1 Introduction ==
	6
	7	A Constraint is a Maintainable Artefact that can be associated to one or more of:
	8
	9	* Data Structure Definition
	10	* Metadata Structure Definition
	11	* Dataflow
	12	* Metadataflow
	13	* Provision Agreement
	14	* Metadata Provision Agreement
	15	* Data Provider or Metadata Provider (this is restricted to a Release Calendar Constraint)
	16	* Simple or Queryable Data Sources
	17	* Dataset
	18	* Metadataset
	19
	20	Note that regardless of the Artefact to which the Constraint is associated, it is constraining the contents of code lists in the DSD to which the constrained object is related. This does not apply, of course, to a Metadata/Data Provider as the latter can be associated, via the (Metadata) Provision Agreement, to many MSDs/DSDs. Hence the reason for the restriction on the type of Constraint that can be attached to a Metadata/Data Provider.
	21
	22	== 10.2 Types of Constraint ==
	23
	24	The Constraint can be of one of two types:
	25
	26	* Data constraint
	27	* Metadata constraint
	28
	29	The Data Constraint may serve two different perspectives, depending on the way the latter is retrieved. These are:
	30
	31	* Allowed constraint
	32	* Actual constraint
	33
	34	The former (allowed – also valid for Metadata Constraint) is specified by a data or metadata provider or consumer for sharing the allowed data and metadata in the context of their DSD or MSD exchanges, e.g., only Monthly data for a specific Dataflow. The latter (actual) is a dynamic Constraint in response to an availability request (only possible for data).
	35
	36	For Actual Data Constraints, there a few characteristics that are worth noting:
	37
	38	* They can only be retrieved by the availability requests (as specified in the REST API).
	39	* They depend on the data available in an SDMX Web Service and thus they can only be dynamically generated according to that data.
	40	* Although they are Maintainable Artefacts, they cannot change independently of data; thus, they cannot be versioned (they are non-versioned, as explained in section 14).
	41	* Their identifier may also be dynamically generated and thus there is no REST resource based on their identification.
	42
	43	== 10.3 Rules for a Constraint ==
	44
	45	=== 10.3.1 Scope of a Constraint ===
	46
	47	A Constraint is used specify the content of a data or metadata source in terms of the component values or the keys.
	48
	49	In terms of data the components are:
	50
	51	* Dimension
	52	* Time Dimension
	53	* Data Attribute
	54	* Measure
	55	* Metadata Attribute
	56	* DataKeySets: the keys are the content of the KeyDescriptor – i.e., the series keys composed, for each key, by a value for each Dimension.
	57
	58	In terms of reference metadata the components are:
	59
	60	* Metadata Attribute
	61
	62	For a Constraint based on a DSD the Constraint can reference one or more of:
	63
	64	* Data Structure Definition
	65	* Dataflow
	66	* Provision Agreement
	67	* Data Provider
	68
	69	For a Constraint based on an MSD the Constraint can reference one or more of:
	70
	71	* Metadata Structure Definition
	72	* Metadataflow
	73	* Metadata Provision Agreement
	74	* Metadata Provider
	75	* Metadata Set
	76
	77	Furthermore, there can be more than one Constraint specified for a specific object e.g., more than one Constraint for a specific DSD.
	78
	79	In view of the flexibility of constraints attachment, clear rules on their usage are required. These are elaborated below.
	80
	81	=== 10.3.2 Multiple Constraints ===
	82
	83	There can be many Constraints for any Constrainable Artefact (e.g., DSD), subject to the following restrictions:
	84
14.1	85	==== 10.3.2.1 Cube Region ====
2.1	86
	87	A Constraint can contain multiple Member Selections (e.g., Dimensions).
	88
	89	* A specific Member Selection (e.g., Dimension FREQ) can only be contained in one Cube Region for any one attached object (e.g., a specific DSD or specific Dataflow).
	90	* Component values within a Member Selection may define a validity period. Otherwise, the value is valid for the whole validity of the Cube Region.
	91	* For partial reference resolution purposes (as per the SDMX REST API), the latest non-draft Constraint must be considered.
	92	* A Member Selection may include wildcarding of values (using character ‘%’ to represent zero or more occurrences of any character), as well as cascading through hierarchic structures (e.g., parents in Codelist), or localised values (e.g., text for English only). Lack of locale means any language may match. Cascading values are mutual exclusive to localised values, as the former refer to coded values, while the latter refer to uncoded values.
	93	* Any values included in a Member Selection for Components with an array data type (i.e., Measures, Attributes or Metadata Attributes), will be applied as single values and will not be assessed combined with other values to match all possible array values. For example, including the Code ‘A’ for an Attribute will allow any instance of the Attribute that includes ‘A’, like [‘A’, ‘B’] or [‘A’, ‘C’, ‘D’]. Similarly, if Code ‘A’ was excluded, all those arrays of values would also be excluded.
	94
14.1	95	==== 10.3.2.2 Key Set ====
2.1	96
	97	Key Sets will be processed in the order they appear in the Constraint and wildcards can be used (e.g., any key position not reference explicitly is deemed to be "all values").
	98
	99	As the Key Sets can be "included" or "excluded" it is recommended that Key Sets with wildcards are declared before KeySets with specific series keys. This will minimize the risk that keys are inadvertently included or excluded.
	100
	101	In addition, Attribute, Measure and Metadata Attribute constraints may accompany KeySets, in order to specify the allowed values per Key. Those are expressed following the rules for Cube Regions, as explained above.
	102
	103	Finally, a validity period may be specified per Key.
	104
	105	=== 10.3.3 Inheritance of a Constraint ===
	106
14.1	107	==== 10.3.3.1 Attachment levels of a Constraint ====
2.1	108
	109	There are three levels of constraint attachment for which these inheritance rules apply:
	110
	111	• DSD/MSD – top level o Dataflow/Metadataflow – second level
	112
	113	▪ Provision Agreement – third level
	114
	115	Note that these rules do not apply to the Simple Datasource or Queryable Datasource; the Constraint(s) attached to these artefacts are resolved for this artefact only and do not take into account Constraints attached to other artefacts (e.g., Provision Agreement, Dataflow, DSD).
	116
	117	It is not necessary for a Constraint to be attached to a higher level artefact. e.g., it is valid to have a Constraint for a Provision Agreement where there are no constraints attached the relevant dataflow or DSD.
	118
14.1	119	==== 10.3.3.2 Cascade rules for processing Constraints ====
2.1	120
	121	The processing of the constraints on either Dataflow/Metadataflow or Provision Agreement must take into account the constraints declared at higher levels. The rules for the lower-level constraints (attached to Dataflow/ Metadataflow and Provision Agreement) are detailed below.
	122
	123	Note that there can be a situation where a constraint is specified at a lower level before a constraint is specified at a higher level. Therefore, it is possible that a higher-level constraint makes a lower-level constraint invalid. SDMX makes no rules on how such a conflict should be handled when processing the constraint for attachment. However, the cascade rules on evaluating constraints for usage are clear – the higher-level constraint takes precedence in any conflicts that result in a less restrictive specification at the lower level.
	124
14.1	125	==== 10.3.3.3 Cube Region ====
2.1	126
	127	It is not necessary to have a Constraint on the higher-level artefact (e.g., DSD referenced by the Dataflow), but if there is such a Constraint at the higher level(s) then:
	128
	129	* The lower-level Constraint cannot be less restrictive than the Constraint specified for the same Member Selection (e.g. Dimension) at the next higher level, which constrains that Member Selection. For example, if the Dimension FREQ is constrained to A, Q in a DSD, then the Constraint at the Dataflow or Provision Agreement cannot be A, Q, M or even just M – it can only further constrain A, Q.
	130	* The Constraint at the lower level for any one Member Selection further constrains the content for the same Member Selection at the higher level(s).
	131	* Any Member Selection, which is not referenced in a Constraint, is deemed to be constrained according to the Constraint specified at the next higher level which constraints that Member Selection.
	132	* If there is a conflict when resolving the Constraint in terms of a lower-level Constraint being less restrictive than a higher-level Constraint, then the Constraint at the higher-level is used.
	133
	134	Note that it is possible for a Constraint at a higher level to constrain, say, four Dimensions in a single Constraint, and a Constraint at a lower level to constrain the same four in two, three, or four Constraints.
	135
14.1	136	==== 10.3.3.4 Key Set ====
2.1	137
	138	It is not necessary to have a Constraint on the higher-level artefact (e.g., DSD referenced by the Dataflow), but if there is such a Constraint at the higher level(s) then:
	139
	140	* The lower-level Constraint cannot be less restrictive than the Constraint specified at the higher level.
	141	* The Constraint at the lower level for any one Member Selection further constrains the keys specified at the higher level(s).
	142	* Any Member Selection, which is not referenced in a Constraint, is deemed to be constrained according to the Constraint specified at the next higher level which constraints that Member Selection.
	143	* If there is a conflict when resolving the keys in the Constraint at two levels, in terms of a lower-level constraint being less restrictive than a higher-level Constraint, then the offending keys specified at the lower level are not deemed part of the Constraint.
	144
	145	Note that a Key in a Key Set can have wildcarded Components. For instance, the Constraint may simply constrain the Dimension FREQ to "A", and all keys where the FREQ="A" are therefore valid.
	146
	147	The following logic explains how the inheritance mechanism works. Note that this is conceptual logic and actual systems may differ in the way this is implemented.
	148
14.2	149	*
2.1	150	*1. Determine all possible keys that are valid at the higher level.
	151	*1. These keys are deemed to be inherited by the lower-level constrained object, subject to the Constraints specified at the lower level.
	152	*1. Determine all possible keys that are possible using the Constraints specified at the lower level.
	153	*1. At the lower level inherit all keys that match with the higher-level Constraint.
	154	*1. If there are keys in the lower-level Constraint that are not inherited then the key is invalid (i.e., it is less restrictive).
	155
	156	=== 10.3.4 Constraints Examples ===
	157
14.2	158	==== 10.3.4.1 Data Constraint and Cascading ====
2.1	159
14.1	160	The following scenario is used.
	161
2.1	162	A DSD contains the following Dimensions:
	163
	164	* GEO – Geography
	165	* SEX – Sex
	166	* AGE – Age
	167	* CAS – Current Activity Status
	168
	169	In the DSD, common code lists are used and the requirement is to restrict these at various levels to specify the actual code that are valid for the object to which the Constraint is attached.
	170
	171	[[image:SDMX 3-0-0 SECTION 6 FINAL-1.0_en_77bea5e.png\|\|height="344" width="554"]]
	172
14.1	173	Figure 20: Example Scenario for Constraints
2.1	174
14.1	175	Constraints are declared as follows:
	176
2.1	177	[[image:SDMX 3-0-0 SECTION 6 FINAL-1.0_en_7c36c475.png\|\|height="356" width="541"]]
	178
	179	Figure 21: Example Constraints
	180
	181	Notes:
	182
	183	AGE is constrained for the DSD and is further restricted for the Dataflow CENSUS_CUBE1.
	184
	185	* The same Constraint applies to both Provision Agreements.
	186
	187	The cascade rules elaborated above result as follows:
	188
	189	DSD
	190
	191	* Constrained by eliminating code 001 from the code list for the AGE Dimension.
	192
	193	Dataflow CENSUS_CUBE1
	194
	195	* Constrained by restricting the code list for the AGE Dimension to codes 002 and 003 (note that this is a more restrictive constraint than that declared for the DSD which specifies all codes except code 001).
	196	** Restricts the CAS codes to 003 and 004.
	197
	198	Dataflow CENSUS_CUBE2
	199
	200	* Restricts the code list for the CAS Dimension to codes TOT and NAP.
	201	** Inherits the AGE constraint applied at the level of the DSD.
	202
	203	Provision Agreement CENSUS_CUBE1_IT
	204
	205	* Restricts the codes for the GEO Dimension to IT and its children.
	206	** Inherits the constraints from Dataflow CENSUS_CUBE1 for the AGE and CAS Dimensions.
	207
	208	Provision Agreement CENSUS_CUBE2_IT
	209
	210	* Restricts the codes for the GEO Dimension to IT and its children.
	211	** Inherits the constraints from Dataflow CENSUS_CUBE2 for the CAS Dimension.
	212	** Inherits the AGE constraint applied at the level of the DSD.
	213
	214	The Constraints are defined as follows:
	215
	216	DSD Constraint
	217
14.2	218	[[image:1747386911707-332.png]]
2.1	219
	220	Dataflow Constraints
	221
14.2	222	[[image:1747386933952-158.png]]
2.1	223
14.2	224	[[image:1747386970127-658.png]]
2.1	225
	226	Provision Agreement Constraint
	227
14.2	228	[[image:1747386991329-805.png]]
2.1	229
14.1	230	==== 10.3.4.2 Combination of Constraints ====
2.1	231
	232	The possible combination of constraining terms are explained in this section, following a few examples.
	233
	234	Let’s assume a DSD with the following Components:
	235
14.2	236	[[image:1747387057775-838.png]]
2.1	237
14.2	238	[[image:1747387089210-741.png]]
	239
2.1	240	On the above, let’s assume the following use cases with their constraining requirements:
	241
14.1	242	===== 10.3.4.2.1 Use Case 1: A Constraint on allowed values for some Dimensions =====
2.1	243
	244	R1: Allow monthly and quarterly data
	245	R2: Allow Mexico for vis-à-vis country
	246
	247	This is expressed with the following CubeRegion:
	248
14.2	249	[[image:1747387154981-708.png]]
2.1	250
14.1	251	===== 10.3.4.2.2 Use Case 2: A Constraint on allowed combinations for some Dimensions =====
2.1	252
	253	R1: Allow monthly data for Germany
	254	R2: Allow quarterly data for Mexico
	255
	256	This is expressed with the following DataKeySet:
	257
14.2	258	[[image:1747387188821-467.png]]
2.1	259
14.2	260	===== 0.3.4.2.3 Use Case 3: A Constraint on allowed values for some Dimensions combined with allowed values for some Attributes =====
2.1	261
	262	R1: Allow monthly and quarterly data
	263	R2: Allow Mexico for vis-à-vis country
	264	R3: Allow present for status
	265
	266	This may be expressed with the following CubeRegion:
	267
14.3	268	[[image:1747387231598-634.png]]
14.2	269
14.1	270	===== 10.3.4.2.4 Use Case 4: A Constraint on allowed combinations for some =====
2.1	271
	272	//Dimensions combined with specific Attribute values//
	273
	274	R1: Allow monthly data, for Germany, with unit euro
	275	R2: Allow quarterly data, for Mexico, with unit usd
	276
	277	This is may be expressed with the following DataKeySet:
	278
14.3	279	[[image:1747387252077-954.png]]
2.1	280
14.4	281	[[image:1747387281625-859.png]]
	282
14.1	283	===== 10.3.4.2.5 Use Case 5: A Constraint on allowed values for some Dimensions together with some combination of Dimension values =====
2.1	284
	285	R1: For annually and quarterly data, for Mexico and Germany, only A status is allowed
	286	R2: For monthly data, for Mexico and Germany, only F status is allowed
	287
	288	Considering the above examples, the following CubeRegions would be created:
	289
14.4	290	[[image:1747387330751-405.png]]
2.1	291
	292	The problem with this approach is that according to the business rule for Constraints, only one should be specified per Component. Thus, if a software would perform some conflict resolution would end up with empty sets for FREQ and OBS_STATUS (as they do not share any values).
	293
	294	Nevertheless, there is a much easier approach to that; this is the cascading mechanism of Constraints (as shown in 10.3.4.1). Hence, these rules would be expressed into two levels of Constraints, e.g., DSD and Dataflows:
	295
	296	DSD CubeRegion:
	297
14.5	298	[[image:1747387369822-932.png]]
	299
2.1	300	Dataflow1 CubeRegion:
	301
14.5	302	[[image:1747387387944-676.png]]
	303
2.1	304	Dataflow2 CubeRegion:
	305
14.5	306	[[image:1747387401689-306.png]]
	307
14.1	308	===== 10.3.4.2.6 Use case 6: A Constraint on allowed values for some Dimensions combined with allowed values for Measures =====
2.1	309
	310	R1: Allow monthly data, for Germany, with unit euro, and measure choice is 'A'
	311	R2: Allow quarterly data, for Mexico, with unit usd, and measure choice is 'B' This is may be expressed with the following DataKeySet:
	312
14.5	313	[[image:1747387437317-733.png]]
	314
14.1	315	===== 10.3.4.2.7 Use Case 7: A Constraint with wildcards for Codes and removePrefix property =====
2.1	316
	317	For this example, we assume that the VIS_CTY representation has been prefixed with prefix ‘AREA_’. In this Constraint, we need to remove the prefix.
	318
	319	R1: Allow monthly and quarterly data
	320	R2: Allow vis-à-vis countries that start with M
	321	R3: Remove the prefix ‘AREA_’
	322
14.6	323	[[image:1747387461703-763.png]]
14.5	324
2.1	325	This may be expressed with the following CubeRegion:
	326
14.1	327	===== 10.3.4.2.8 Use Case 8: A Constraint with multilingual support on Attributes =====
2.1	328
	329	R1: Allow monthly and quarterly data
	330	R2: Allow Mexico for vis-à-vis country
	331	R3: Allow a comment, in English, which includes the term adjusted for status
	332
	333	This may be expressed with the following CubeRegion:
	334
14.6	335	[[image:1747387484366-337.png]]
2.1	336
14.1	337	===== 10.3.4.2.9 Use Case 9: A Constraint on allowed values for Dimensions combined with allowed values for Metadata Attributes =====
2.1	338
	339	R1: Allow monthly and quarterly data
	340
	341	R2: Allow Mexico for vis-à-vis country
	342
	343	R3: Allow John Doe for contact
	344
	345	This may be expressed with the following CubeRegion:
	346
	347	\|FREQ\|M, Q
	348	\|VIS_CTY\|MX
	349	\|CONTACT\|John Doe
	350
14.1	351	==== 10.3.4.3 Other constraining terms ====
2.1	352
	353	Beyond the cube regions and keysets, there is one more constraining term, i.e., the ReleaseCalendar.
	354
	355	The ReleaseCalendar is the only term that does not apply on Components; it specifies the schedule of publication or reporting of the dataset or metadataset.
	356
	357	For example, the ReleaseCalendar for Provider BIS, is specified in the three following terms:
	358
	359	* Periodicity: how often data should be reported, e.g., monthly
	360	* Offset: the number of days between the 1^^st^^ of January and the first release of data, e.g., 10 days
	361	* Tolerance: the maximum allowed of days that data may be considered, without being considered as late, e.g., 5 days
	362
	363	With the above terms, BIS would need to report data between the 10^^th^^ and 15^^th^^ of every month.
	364
	365	NOTE: The SDMX 2.1 constraining term ReferencePeriod has been deprecated in SDMX 3.0; thus, the TimeDimension and any Dimension with a time Representation can be constrained within a CubeRegion or MetadataTargetRegion, using the TimeRangeValue.