ler Handler (OBH) Concrete object (OBH) Concrete object Concrete object The service network: service service object object service service object object Fig. 2.52 Disintegration: abstract network -> service network The OPH translates between events in local, concrete language interfaces and events of the abstract protocol. An OPH also handles the event interface and can perform some other functions, like operation synchronization and handling timing requirements. The generic event handler model is applied to the abstract protocol at the top of Fig. 2.52. An abstract machine can comprise a single service object, in which case the generic model does not apply. In Fig. 2.52, however, it is assumed that the machine to the left comprises three objects, one of which is the OBH. The other two objects are instantiated on request from the abstract machine to the right. The abstract machine to the right comprises two objects. The view of a service object is created by the OPH, which translates communication between concrete objects to communication between service objects ("abstract objects"), defined by the abstract protocol. Thus, the OPH creates language transparency in object commu- nication. The service network that is visible in the abstract protocol is shown at the bot- tom of Fig. 2.52. Within an abstract network, the service relation to the OBH is per- 2.3 Architectural Principles manent, compared to service relations to other service objects. The fact that service objects may have a temporary existence is shown in the service network by draw- ing such objects with a dotted boundary. How access is provided to such objects is first determined when service networks are integrated in abstract networks. Integra- tion of service networks in abstract networks may require that service objects must use some extra operations, defined by the abstract protocol. Note, however, that a service network model is independent of how service objects are accessed and allocated in abstract machines. Another integration solution would 