Describing services and requests
Service points
Services assured by resource architecture elements are represented by some
service points 
.
The service is requested according to precise terms defined by an exchange contract assigned to the service point.
Resources activated to assure a service are linked to the service point by interactions. If activation of several resources is necessary, then several interactions must be created between the service point and the architecture resources.
In the example here, the support service is linked to two interactions, based on the same contract, that represent activation of one support center or another as a function of time slot.
Request points
A
request point 
enables representation of use of an external service.
The service is requested according to precise terms defined by an exchange contract assigned to the request point.
Resources that issue a request are linked to the request point by an interaction.
In the example, request points represent service requests made between call center operators and other organizations.