HOPEX IT Architecture V2 > Modeling IT Infrastructures > Describing communications in a Technical Infrastructure > Describing services and requests
Describing services and requests
Service points  
Services assured by resource architecture elements are represented by service points .
*A service point is a point of exchange by which an agent offers a service to potential customers.
The service is requested according to precise terms defined by an exchange contract assigned to the service point.
*An exchange contract is a model of a contract between organizational entities. This contract is described by exchanges between an initiator role and one or several contributor roles.
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.
To create a service point, see Creating a Service Point or a Request Point.
Request points 
A request point enables representation of use of an external service.
*A request point is a point of exchange by which an agent requests a service from potential suppliers.
The service is requested according to precise terms defined by an exchange contract assigned to the request point.
*An exchange contract is a model of a contract between organizational entities. This contract is described by exchanges between an initiator role and one or several contributor roles.
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.
The request point creation procedure is identical to that for service points. For more details, see Creating a Service Point or a Request Point.