s such, these collaborations are not syn- chronized, and horizontal coordination between the collaboration uses is not shown in this view, as the receptionist is responsible for translating information received from the patient to the appropriate form required for entering into the electronic service desk. This is why the two collaboration uses for call and registra- tion are shown in parallel in Figure 5.8 (using the UML 2.x notation where a heavy bar represents a fork or a join). Evaluation of PDP2_Rule1 is triggered How to Model Dynamic Service Composition Using UML 2.x PESM aided Registration PDP3_Rule1 T: ! (Answer, reg assister, PDP2_Rule1 assisted caller) T: ? (Request registration, External, C: True, reg assister. assisted caller) AssistedcallerInCall, C: True, assisted caller. assisting registrar.onLine NeedsAssistance, G: reg assister. reg assister.onDuty AssistedcallerRegistered, G: assisted caller.TalkedTo(Callee), assisting registrar. reg assister.TalkedTo(Caller) registration Complete rrs (registeree ->reg assister, pcr (caller ->assisted caller, registrar -> assisting registrar) : callee -> reg assister) : call registration Figure 5.8 Global PESM diagram for the aided registration service. when the assisted caller, bound to the PatientT composite role, receives a request for registration. If the given condition evaluates to true, the call collabora- tion should be performed. The goal is that afterward both the patient and the receptionist should have reached a status of having talked to each other. Similarly, the evaluation of PDP3 Rule1 is triggered when the Answer message of the call collaboration is sent from the reg assister to the assisted caller, bound to the ReceptionistT and PatientT composite roles, respectively. During consultation, the doctor is in a call with the patient. At the same time, the doctor is interacting with the electronic tele-consultation service desk in order to obtain patient data as well as record information in the patient journal. As can be seen in Figure 5.9, the com