ur **) Agents and actors Object (see Fig. 7.2) defines Object Resource Resource irr internal resource relation relatedByErr*) err external resource relation arr abstraction resource relation relatedByArr*) Fig. 7.14 Properties of primitive service objects and ports The specification of a primitive service is associated with the provider port of a service object. A primitive service stands for all properties that can be associated with a pro- vider port. As we saw in Sect 6.2, there are three main properties: service resources related by internal resource relations (irr), a set of operations based on service resources and a service behaviour. Service objects use primitive services in their user ports. The part of the pro- vided service that is used is called the used primitive service. Two properties are associated with agents and actors: object resources, related by external resource relations (err) and abstraction resource relations (arr), and the object behaviour. Figure 7.15 defines information elements that are used to specify properties in service networks. Producing primitive service specifications is at the heart of serv- ice network modelling, and represents the bulk of the effort in service network modelling. Using primitive service specifications to produce service object specifi- cations is guided by the service network model. Compared to primitive service specification, specifying service objects is rather trivial, once the service network is defined and all primitive services are specified. The primitive service specifica- tion itself is a simple information element, since its major purpose is to manage ref- erences to three more basic types of information elements: the service resource model, the operation specifications and the service behaviour specification. 7.3 Resource Model Notation Primitive Provided describes Service Service Primitive Object Specification Service Specification refers /1..* Service Operation Service 1.. * Object Object Behaviour Specification Resource Resource Resource Behavi