osed (sub-)service described recursively as a UML 2.x col- laboration overview diagram in the same manner as described here. 3. The binding of the (elementary or composite) roles in the collaboration uses to the composite roles from Step 1. The resulting diagram then provides a means of statically and structurally rep- resenting the binding of collaboration uses involved in the composed service to the actual service parts. Any of the collaboration uses involved in the composed service may be selected from a repository of reusable service specifications. Step 1 applied to the tele-consultation service: The UML 2.x collaboration overview diagram produced for the tele-consultation service is shown above in Figure 5.2. In order to arrive at this collaboration overview, the following steps were taken: 1. The distributed parts involved in the composed service are PatientT, ReceptionistT, DoctorT, and TeleSvcDsk, given as composite roles in the collaboration overview diagram. 2. The tele-consultation service is composed of three collaboration uses: one for consultation, one for registration, and one for aided registration. a. Several elementary collaborations are used in the tele-consultation ser- vice. The registration collaboration is shown above in Figure 5.3. Here we also show the call collaboration in Figure 5.16. This elemen- tary collaboration, which is used in the aided Registration and consultation collaborations, models a two-way multimedia commu- nication between two parties such as a telephone call. The collaboration diagrams for the two composite subservices used in the tele-consultation service are aided Registration, shown above in Figure 5.4, and consultation, shown here in Figure 5.17. In addition to using the elementary call collaboration, aided Registration also uses the elementary registration collaboration and consul- tation uses the elementary administrate collaboration. Service Delivery Platforms Caller Callee Figure 5.16 The call collaboration. 3. The binding of the (elementary or composite) role