AtlasRelationshipDef is a TypeDef that defines a relationship. As with other typeDefs the AtlasRelationshipDef has a name. Once created the RelationshipDef has a guid. The name and the guid are the 2 ways that the RelationshipDef is identified. RelationshipDefs have 2 ends, each of which specify cardinality, an EntityDef type name and name and optionally whether the end is a container. RelationshipDefs can have AttributeDefs - though only primitive types are allowed. RelationshipDefs have a relationshipCategory specifying the UML type of relationship required The way EntityDefs and RelationshipDefs are intended to be used is that EntityDefs will define AttributeDefs these AttributeDefs will not specify an EntityDef type name as their types. RelationshipDefs introduce new attributes to the entity instances. For example EntityDef A might have attributes attr1,attr2,attr3

EntityDef B might have attributes attr4,attr5,attr6 RelationshipDef AtoB might define 2 ends

end1: type A, name attr7 end2: type B, name attr8

When an instance of EntityDef A is created, it will have attributes attr1,attr2,attr3,attr7 When an instance of EntityDef B is created, it will have attributes attr4,attr5,attr6,attr8

In this way relationshipDefs can be authored separately from entityDefs and can inject relationship attributes into the entity instances