IBM BPM, V8.0.1, All platforms > Authoring services in Integration Designer > Defining and transforming data > Create relationships
Identity relationships versus non-identity relationships
There are two different types of relationships: identity and non-identity relationships. An identity relationship is a one-to-one relationship. There must be one managed role defined in the identity relationship, which represents the generic data type and is managed by the relationship service. A non-identity relationship differs slightly from the identity relationship. The non-identity relationship is also called a relationship one-to-many or many-to-many relationship.
In an identity relationship there is a unique mapping between the key attributes of Role A to the key attributes of Role B within the same instance. Instance means the instance of role data in the relationship service runtime environment (essentially a table containing data - instances are one row of that table).
There are also combined keys allowed in identity relationships. Combined keys are represented by several key attributes defined for one role. An exception for combined keys is the managed role of the identity relationship. The managed role of the identity relationship must have only one key attribute defined, there are no combined keys allowed for the managed role.
During the creation of the relationships, the differences are not overtly apparent. You do not need a managed role for a non-identity relationship and it is also not recommended to use a managed role. The main difference is that during runtime the mapping of the key attribute values is not unique. This means the key attribute LastName in Role A may have the value " Doe" specified, which will be mapped to key attribute GivenName in Role B with the values " John", " Mary", " George". This would be a one-to-many mapping. In non-identity relationships, there are also combined keys allowed as in identity relationships.