Product Information Graph
Properties
▣ Metamodel
The metamodel is a 'platform independent model' in OMG terms and defines both the classes (top) and their instances (bottom) for the Product Information Graph (PIG):
- pig:EntityClass and pig:Entity are used for model elements, such as a system component or a requirement.
- pig:RelationshipClass and pig:Relationship are used for relations between entities, such as a 'system component satisfies a requirement'. A relationship class may define the classes of entities or relationships, whose instances are eligible as subject or object in a relationship.
- pig:OrganizerClass and pig:Organizer are used for diagrams, chapters, folders or similar with links to any pig:ModelElement, which is an entity or relationship. An organizer class may define the classes of entities or relationships, whose instances are eligible to be linked (i.e. organized).
- Every pig:OrganizerClass, pig:EntityClass and pig:RelationshipClass can define an individual set of pig:PropertyClasses, each of which specifies a data type. For example, a requirement might have three property classes, such as a „Title“ with data type „String of max. length 96“, a „Description“ with data type „String“ without restriction and a „Priority“ with data type „String with a single choice of ['(1) high', '(2) medium', '(3) low']“.
- A data type may be any of those known from XML. As described above, some parameters may restrict the value range, such as minimum and/or maximum value of a number, the number of decimals of a real number, a string length or a set of enumerated values.
- pig:Organizer, pig:Entity or pig:Relationship is an instance of a pig:OrganizerClass, pig:EntityClass or pig:RelationshipClass respectively. Each instance usually has a set of pig:Property corresponding with the pig:PropertyClasses of its class.
Note:
- The prefixes 'pig*', 'xs*' and 'dcterms*' designate namespaces. In other technical environments such as RDF, XML and JSON, a namespace would be separated with ':' more appropriately, which may lead to confusion in UML. The separator '*' may be replaced during transformation.
- As usual, the classes with white background and italic name are abstract.
Properties
| Element Type | Model Diagram |
| Notation | UML Class Diagram |
Statements
☆ pig:ConfigurationItem
All specializations are identifiable and under revision control.
Details:
- The class is abstract.
- All attributes are inherited by its subclasses.
Properties
Statements
○ pig:id
Properties
Statements
○ pig:revision
Properties
Statements
○ dcterms:modified
Properties
Statements
○ dcterms:creator
Properties
Statements
☆ pig:Class
A superclass of all data types and all classes for organizers, entities, relationships as well as properties.
Details:
- dcterms:title is the name of the class, most often an ontology term for entity classes resp. relationship classes.
- dcterms:description is the definition of the ontology term
- The class is abstract.
- All attributes are inherited by its subclasses.
Properties
Statements
○ dcterms:title
Properties
Statements
○ dcterms:description
Properties
Statements
☆ pig:ElementClass
A superclass of pig:EntityClass (type of graph node), pig:RelationshipClass (type of graph edge) and pig:OrganizerClass (type of diagrams, folders etc.). Any of those classes may be selected by a pig:OrganizerClass to restrict the type of pig:Elements. Thus, a folder class may be defined allowing its instances to contain activity diagrams and activities, but not any other.
Details:
- The class is abstract.
- All attributes and associations are inherited by its subclasses.
Properties
Statements
☆ pig:ModelElementClass
A superclass of pig:EntityClass (type of graph node) and pig:RelationshipClass (type of graph edge).
Details:
- The class is abstract.
- All attributes and associations are inherited by its subclasses.
Properties
Statements
○ pig:icon
Properties
Statements
☆ pig:EntityClass
pig:EntityClass is used for types of model elements, such as a system component or a requirement.
Details:
- An entity should have a title (name) and may have a description (definition).
- An entity class lists one to many classes of properties its instances may have. (No propertyClass at all is formally allowed to be consistent with other elements, but an entitiy without property has no reason to exist.)
- The definitions of the entity class together with those of the property classes may be used to build user dialogs and to check its instances whether all properties have a correct type and value range as well as whether all required ones are present.
Properties
Statements
☆ pig:PropertyClass
Every pig:EntityClass, pig:RelationshipClass and pig:OrganizerClass can have an individual set of pig:PropertyClasses, each of which is uniquely defined by a data type. For example, a requirement might have three pig:PropertyClasses, such as a „Title“ with data type „String of max. length 96“, a „Description“ with data type „String of max. length 8192“ and a „Priority“ with data type „String with a single choice of ['(1) high', '(2) medium', '(3) low']“.
Details:
- A property class must have a title named dcterms:title and may have a description named dcterms:description.
- A property class may define a minimum and maximum count of values.
- A property class may define default value(s) which must of course satisfy its own constraints and those of its data type.
- A property class may be composed of multiple property classes to form a structured data type (xs:complexType). The structure must be a tree, i.e without cyclic dependency.
Properties
Statements
○ sh:datatype
One of the xs: data types.
tbd: Use 'xs:type' instead?
Properties
Statements
○ sh:minCount
tbd: Use 'xs:minOccurs' instead?
Properties
Statements
○ sh:maxCount
tbd: Use 'xs:maxOccurs' instead?
Properties
Statements
○ xs:maxLength
Properties
Statements
○ xs:minInclusive
Properties
Statements
○ xs:maxInclusive
Properties
Statements
○ xs:fractionDigits
Properties
Statements
○ xs:restriction
tbd: Use 'sh:in' instead?
Properties
Statements
○ sh:defaultValue
Optional default value(s) in case a modelElement's property does not have an individual value. It is a list of multiple values, if maxCount is undefined or >1, or a single value otherwise.
Here, the attribute is called 'defaultValue' for clarity and may just be called 'values' in an implementation, as all restrictions and operations of a property's values apply.
Properties
Statements
☆ pig:OrganizerClass
pig:OrganizerClass is used for types of diagrams, chapters, folders and similar with links to any pig:Element, which is an entity, relationship or organizer.
Details:
- An organizer class must have a title (name) and may have a description (definition).
- An organizer class lists one to many classes of properties its instances may have.
- An organizer class may define the classes of entities, relationships or organizers, whose instances are eligible to be linked (i.e. organized). If none are defined, all entities, relationships and organizers are eligible.
- The definitions of the organizer class together with those of the property classes may be used to build user dialogs and to check its instances whether all properties have a correct type and value range as well as whether all required ones are present.
Properties
Statements
☆ pig:RelationshipClass
pig:RelationshipClass is used for types of relations between two entities, such as a 'system component satisfies a requirement'. All relationships are bilateral and directed. This allows for assertions according to propositional logic. They can be easily mapped to many technologies such as RDF or ReqIF.
Details:
- A relationship class must have a title (name) and may have a description (definition).
- A relationship class lists zero to many classes of properties its instances may have.
- A relationship class may define entitiy classes or relationship classes, whose instances are eligible as subject or object in a relationship. If none are defined, all entities and relationships are eligible.
- The definitions of the relationship class together with those of the property classes may be used to build user dialogs and to check its instances whether all properties have a correct type and value range as well as whether all required ones are present.
Properties
Statements
☆ pig:Element
A superclass of pig:ModelElement and pig:Organizer. Thus, an instance of pig:Organizer may be related with pig:hasElement to any instance of pig:Entity, pig:Relationship or pig:Organizer, as long as the related element's class is among the pig:OrganizerClass' eligible element classes.
Details:
Properties
Statements
☆ pig:ModelElement
A superclass of pig:Entity (graph node) and pig:Relationship (reified graph edge). Thus, an instance of pig:Relationship may be related to any pig:Entity or pig:Relationship with pig:hasSubject and pig:hasObject.
Details:
Properties
Statements
☆ pig:Property
Each property belongs to a single entity or relationship, wheras
- an entity may have 1 to many properties and
- a relationship may have 0 to many properties.
Details:
- A property must have one to many values according to the constraints of its property class and data type.
- A property without value is omitted as a whole, as there is no need of a place-holder.
- A property may be composed of multiple properties to form a structured data set according to its property class.
Properties
Statements
○ pig:value
Properties
Statements
☆ pig:Organizer
pig:Organizer is used for diagrams, chapters, folders and similar with links to any pig:Element, which is an entity, relationship or organizer. An organizer class may define the classes of entities, relationships or organizers, whose instances are eligible to be linked (i.e. organized).
Details:
- An organizer must have at least one link to an entity, relationship or organizer with a class defined in its pig:OrganizerClass. If none is defined, all entities, relationships and organizers are eligible.
- A organizer may have zero to many properties as defined in its class.
- The definitions of the organizer class together with those of the property classes may be used to build user dialogs and to check its instances whether all properties have a correct type and value range as well as whether all required ones are present.
Properties
Statements
☆ pig:Entity
pig:Entity is used for model elements, such as a system component or a requirement.
Details:
- An entity shpuld have at least one property as properties are the only payload an entity can carry. (No property at all is formally allowed to be consistent with other elements, but an entitiy without property has no reason to exist.)
- The entity's class lists the classes of properties it may have.
- The definitions of the entity class together with those of the property classes may be used to build user dialogs and to check its instances whether all properties have a correct type and value range as well as whether all required ones are present.
Properties
Statements
☆ pig:Relationship
pig:Relationship is used for relations between entities, such as a 'system component satisfies a requirement'. All relationships are bilateral and directed. This allows for assertions according to propositional logic. They can be easily mapped to many technologies such as RDF or ReqIF.
Details:
- A pig:Relationship is a reified graph edge and must have exactly one subject and object entity each. The subject must be an entity or relationship with a class defined by an eligible subject class of its pig:RelationshipClass. The same applies for the object.
- A relationship may have zero to many properties as defined in its class.
- The definitions of the relationship class together with those of the property classes may be used to build user dialogs and to check its instances whether all properties have a correct type and value range as well as whether all required ones are present.
Properties
Statements
☆ pig:HierarchyRoot
pig:HierarchyRoot anchors hierarchies (trees) whose leaves point to a pig:Entity each. Thus, hierarchies with their items organize entities for a given target group or purpose, such as a bill of material (BoM) or a document outline. A given entity may be referenced by none, one or multiple items in one or more hierarchies.
Properties
Model Elements (Glossary)
Properties
| Element Type | Model Elements (Glossary) |
○ dcterms:creator
Properties
Statements
○ dcterms:description
Properties
Statements
○ dcterms:modified
Properties
Statements
○ dcterms:title
Properties
Statements
☆ pig:Class
A superclass of all data types and all classes for organizers, entities, relationships as well as properties.
Details:
- dcterms:title is the name of the class, most often an ontology term for entity classes resp. relationship classes.
- dcterms:description is the definition of the ontology term
- The class is abstract.
- All attributes are inherited by its subclasses.
Properties
Statements
☆ pig:ConfigurationItem
All specializations are identifiable and under revision control.
Details:
- The class is abstract.
- All attributes are inherited by its subclasses.
Properties
Statements
☆ pig:Element
A superclass of pig:ModelElement and pig:Organizer. Thus, an instance of pig:Organizer may be related with pig:hasElement to any instance of pig:Entity, pig:Relationship or pig:Organizer, as long as the related element's class is among the pig:OrganizerClass' eligible element classes.
Details:
Properties
Statements
☆ pig:ElementClass
A superclass of pig:EntityClass (type of graph node), pig:RelationshipClass (type of graph edge) and pig:OrganizerClass (type of diagrams, folders etc.). Any of those classes may be selected by a pig:OrganizerClass to restrict the type of pig:Elements. Thus, a folder class may be defined allowing its instances to contain activity diagrams and activities, but not any other.
Details:
- The class is abstract.
- All attributes and associations are inherited by its subclasses.
Properties
Statements
☆ pig:Entity
pig:Entity is used for model elements, such as a system component or a requirement.
Details:
- An entity shpuld have at least one property as properties are the only payload an entity can carry. (No property at all is formally allowed to be consistent with other elements, but an entitiy without property has no reason to exist.)
- The entity's class lists the classes of properties it may have.
- The definitions of the entity class together with those of the property classes may be used to build user dialogs and to check its instances whether all properties have a correct type and value range as well as whether all required ones are present.
Properties
Statements
☆ pig:EntityClass
pig:EntityClass is used for types of model elements, such as a system component or a requirement.
Details:
- An entity should have a title (name) and may have a description (definition).
- An entity class lists one to many classes of properties its instances may have. (No propertyClass at all is formally allowed to be consistent with other elements, but an entitiy without property has no reason to exist.)
- The definitions of the entity class together with those of the property classes may be used to build user dialogs and to check its instances whether all properties have a correct type and value range as well as whether all required ones are present.
Properties
Statements
○ pig:icon
Properties
Statements
○ pig:id
Properties
Statements
☆ pig:ModelElement
A superclass of pig:Entity (graph node) and pig:Relationship (reified graph edge). Thus, an instance of pig:Relationship may be related to any pig:Entity or pig:Relationship with pig:hasSubject and pig:hasObject.
Details:
Properties
Statements
☆ pig:ModelElementClass
A superclass of pig:EntityClass (type of graph node) and pig:RelationshipClass (type of graph edge).
Details:
- The class is abstract.
- All attributes and associations are inherited by its subclasses.
Properties
Statements
☆ pig:Organizer
pig:Organizer is used for diagrams, chapters, folders and similar with links to any pig:Element, which is an entity, relationship or organizer. An organizer class may define the classes of entities, relationships or organizers, whose instances are eligible to be linked (i.e. organized).
Details:
- An organizer must have at least one link to an entity, relationship or organizer with a class defined in its pig:OrganizerClass. If none is defined, all entities, relationships and organizers are eligible.
- A organizer may have zero to many properties as defined in its class.
- The definitions of the organizer class together with those of the property classes may be used to build user dialogs and to check its instances whether all properties have a correct type and value range as well as whether all required ones are present.
Properties
Statements
☆ pig:OrganizerClass
pig:OrganizerClass is used for types of diagrams, chapters, folders and similar with links to any pig:Element, which is an entity, relationship or organizer.
Details:
- An organizer class must have a title (name) and may have a description (definition).
- An organizer class lists one to many classes of properties its instances may have.
- An organizer class may define the classes of entities, relationships or organizers, whose instances are eligible to be linked (i.e. organized). If none are defined, all entities, relationships and organizers are eligible.
- The definitions of the organizer class together with those of the property classes may be used to build user dialogs and to check its instances whether all properties have a correct type and value range as well as whether all required ones are present.
Properties
Statements
☆ pig:Property
Each property belongs to a single entity or relationship, wheras
- an entity may have 1 to many properties and
- a relationship may have 0 to many properties.
Details:
- A property must have one to many values according to the constraints of its property class and data type.
- A property without value is omitted as a whole, as there is no need of a place-holder.
- A property may be composed of multiple properties to form a structured data set according to its property class.
Properties
Statements
☆ pig:PropertyClass
Every pig:EntityClass, pig:RelationshipClass and pig:OrganizerClass can have an individual set of pig:PropertyClasses, each of which is uniquely defined by a data type. For example, a requirement might have three pig:PropertyClasses, such as a „Title“ with data type „String of max. length 96“, a „Description“ with data type „String of max. length 8192“ and a „Priority“ with data type „String with a single choice of ['(1) high', '(2) medium', '(3) low']“.
Details:
- A property class must have a title named dcterms:title and may have a description named dcterms:description.
- A property class may define a minimum and maximum count of values.
- A property class may define default value(s) which must of course satisfy its own constraints and those of its data type.
- A property class may be composed of multiple property classes to form a structured data type (xs:complexType). The structure must be a tree, i.e without cyclic dependency.
Properties
Statements
☆ pig:Relationship
pig:Relationship is used for relations between entities, such as a 'system component satisfies a requirement'. All relationships are bilateral and directed. This allows for assertions according to propositional logic. They can be easily mapped to many technologies such as RDF or ReqIF.
Details:
- A pig:Relationship is a reified graph edge and must have exactly one subject and object entity each. The subject must be an entity or relationship with a class defined by an eligible subject class of its pig:RelationshipClass. The same applies for the object.
- A relationship may have zero to many properties as defined in its class.
- The definitions of the relationship class together with those of the property classes may be used to build user dialogs and to check its instances whether all properties have a correct type and value range as well as whether all required ones are present.
Properties
Statements
☆ pig:RelationshipClass
pig:RelationshipClass is used for types of relations between two entities, such as a 'system component satisfies a requirement'. All relationships are bilateral and directed. This allows for assertions according to propositional logic. They can be easily mapped to many technologies such as RDF or ReqIF.
Details:
- A relationship class must have a title (name) and may have a description (definition).
- A relationship class lists zero to many classes of properties its instances may have.
- A relationship class may define entitiy classes or relationship classes, whose instances are eligible as subject or object in a relationship. If none are defined, all entities and relationships are eligible.
- The definitions of the relationship class together with those of the property classes may be used to build user dialogs and to check its instances whether all properties have a correct type and value range as well as whether all required ones are present.
Properties
Statements
○ pig:revision
Properties
Statements
○ pig:value
Properties
Statements
○ sh:datatype
One of the xs: data types.
tbd: Use 'xs:type' instead?
Properties
Statements
○ sh:defaultValue
Optional default value(s) in case a modelElement's property does not have an individual value. It is a list of multiple values, if maxCount is undefined or >1, or a single value otherwise.
Here, the attribute is called 'defaultValue' for clarity and may just be called 'values' in an implementation, as all restrictions and operations of a property's values apply.
Properties
Statements
○ sh:maxCount
tbd: Use 'xs:maxOccurs' instead?
Properties
Statements
○ sh:minCount
tbd: Use 'xs:minOccurs' instead?
Properties
Statements
○ xs:fractionDigits
Properties
Statements
○ xs:maxInclusive
Properties
Statements
○ xs:maxLength
Properties
Statements
○ xs:minInclusive
Properties
Statements
○ xs:restriction
tbd: Use 'sh:in' instead?
Properties
Statements