Changes for page Technical details

Last modified by lzehl on 2021/07/05 18:57
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edited by lzehl
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18 18  === The openMINDS schema template syntax ===
19 19  
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21 -All openMINDS metadata models use a light-weighted schema template syntax for defining the metadata. The correspondingly formatted schema files use the extension: **##.schema.tpl.json##**.
21 +All openMINDS metadata models use a light-weighted schema template syntax for defining the expected metadata. The correspondingly formatted schema files use the extension: **##.schema.tpl.json##**.
22 22  
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24 -Although, as the file extension suggests, this openMINDS schema template syntax is inspired by JSON-Schema, it facilitates or even excludes technical aspects that are generally expected for the openMINDS schemas making it more human-readable, especially for untrained eyes. Behind the scenes, within the openMINDS integration pipeline (cf. below), this schema template syntax is then interpreted and flexibly translated to various formal metadata formats (e.g., JSON-Schema).
24 +Although, as the file extension suggests, this openMINDS schema template syntax is inspired by JSON-Schema, it facilitates or even excludes technical aspects that are generally expected for the openMINDS schemas making them more human-readable, especially for untrained eyes. Behind the scenes, within the openMINDS integration pipeline (cf. below), this schema template syntax is then interpreted and flexibly translated to various formal metadata formats (e.g., JSON-Schema).
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27 -Despite the simplification in comparison to JSON-Schema, the openMINDS schema templates are also, at the core, specially formatted JSON files using a particular syntax, meaning special key-value pairs that define the validation rules of a schema. Please find in the following a full documentation of the openMINDS schema template syntax and how the key-value pairs need to be defined and interpreted.
27 +Despite the simplification in comparison to JSON-Schema, the openMINDS schema templates are also, at the core, specially formatted JSON files using a particular syntax, meaning special key-value pairs that define the validation rules of a schema.
28 28  
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30 -===== Target & context templates =====
30 +Please find in the following a full documentation of the openMINDS schema template syntax and how it's key-value pairs need to be defined and interpreted.
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33 -An openMINDS schema //HAS TO HAVE// a **##"_type"##** to be recognized as **target template**. In other words, the **##"_type"##** is used to define the openMINDS namespace of a corresponding schema using the following naming convention:
33 +===== Target & concept templates =====
34 34  
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36 -**##"_type": "https:~/~/openminds.ebrains.eu/<<schema-model>>/<<schema-name>>"##**,
37 -
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39 -where **##<<schema-model>>##** has to be replaced with the label of the openMINDS metadata model the corresponding schema belongs to and **##<<schema-name>>##** exchanged with the label of that schema.
36 +Same as in JSON-Schema, all openMINDS schema templates define the expected name (written in **##lowerCamelCase##**) and value of the metadata, typically called property, under the key **##properties##** as nested dictionaries. Furthermore, the names of obligatory metadata can be listed under the key **##required##**. Here a generalized example:
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42 -If an openMINDS schema template file //DOES NOT// define a **##"_type"##**, it is interpreted as a **context template** which //HAS TO BE// extended to a target template with a corresponding openMINDS namespace. The context and corresponding target templates have to be located in the same openMINDS metadata model repository.
38 +{{code language="json"}}
39 +{
40 + "properties": {
41 + "propertyNameA": {},
42 + "propertyNameB": {},
43 + "propertyNameC": {}
44 + },
45 + "required": [
46 + "propertyNameA",
47 + "propertyNameC"
48 + ]
49 +}
50 +{{/code}}
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45 -Context templates are and should be used when multiple openMINDS schemas (target templates) have the same subset of properties. This common subset of properties can then be defined within a single context schema instead of each target template which facilitates the long-term maintenance of these properties.
53 +In addition, an openMINDS schema //has to have// a key **##"_type"##** to be recognized as **target template**. In other words, the **##"_type"##** is used to define the openMINDS namespace of a corresponding schema using a particular naming convention. Here again a generalized example:
46 46  
55 +{{code language="json"}}
56 +{
57 + "_type": "https:~/~/openminds.ebrains.eu/<<schema-model>>/<<schema-name>>",
58 + "properties": {}
59 +}
60 +{{/code}}
61 +
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48 -To define that a target template is the extension of a context template, the target template can state under **##"_extends"##** the relative path to the context template.
63 +Note that **##<<schema-model>>##** has to be replaced with the label of the openMINDS metadata model to which the corresponding schema belongs to, and **##<<schema-name>>##** has to be replaced with the corresponding name of the schema (written in **##CamelCase##**).
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51 -===== String properties =====
66 +If an openMINDS schema template //does not// define a key **##"_type"##** (as in the first example above), it is interpreted as a **concept template** which //has to be// extended to a target template.
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54 -(//**coming soon**//)
69 +Concept templates are and should be used when multiple target templates have the same subset of properties, because they facilitate the long-term maintenance of those shared properties: Instead of defining the same properties repeatedly within multiple target templates, the common subset can be defined within a single concept template and passed on to all extending target templates.
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57 -===== Numerical properties =====
72 +To define that a target template is the extension of a concept template, the target template can state under **##"_extends"##** the relative path to the concept template. For example, the openMINDS core target template **##Dataset##** extends the core concept template **##researchProduct##** as indicated here:
58 58  
74 +{{code language="json"}}
75 +{
76 + "_type": "https:~/~/openminds.ebrains.eu/core/Dataset",
77 + "_extends": "products/researchProduct.schema.tpl.json"
78 +}
79 +{{/code}}
80 +
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60 -(//**coming soon**//)
82 +Note that this convention requires the concept and corresponding target templates to be located in the same openMINDS metadata model repository. Note also that for properties, the following rules apply for target and concept template: 
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84 +1. A concept template has to define some properties which will be inherited by all extending target templates.
85 +1. If a concept template additionally states that some of these properties are required, all extending target templates will require the same properties. 
86 +1. A target template can require properties of the concept template, that are not explicitly required within the concept template. In such a case, the other target templates extending the same concept template will not require those properties.
87 +1. A target template can (but does not have to) define and require additional properties that were not defined and required in the concept template. These additionally defined and required properties will not be shared with the other target templates extending the same concept template.
88 +
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63 -===== Object properties =====
90 +How to define the expected value of a property will be explained for the different property types in the following sections.
64 64  
65 65  (% style="text-align: justify;" %)
66 -(//**coming soon**//)
93 +===== Defining expected values =====
67 67  
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69 -===== Property arrays =====
96 +The expected value of a property can be defined in large parts in the same way as in JSON-Schema, with some openMINDS syntax specific simplifications and modifications.
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72 -(//**coming soon**//)
99 +On the first level, the **##"type"##** of the expected property value needs to be defined. In principle, the openMINDS template syntax supports the same value types as JSON-Schema Draft 7.0, meaning:
100 ++ **##"string"##**
101 ++ **##"number"##**
102 ++ **##"integer"##**
103 ++ **##"array"##**
104 ++ **##"boolean"##**
105 ++ **##"null"##**
106 ++ **##"object"##**
73 73  
108 +Also very similar to JSON-Schema, additional type-specific keys can be used to set further requirements for the expected value. H
74 74  
110 +
75 75  === The openMINDS integration pipeline ===
76 76  
77 77  (//**coming soon**//)
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