In a BPEL process, interactions between business partners are defined by partner links. The definitions are abstract and do not contain any access information about actual running services. The reason you would omit real access information is to allow the process definition to be reused for many services.

How do the actual services get accessed? A service is identified in two ways: outside of the process at deployment time or within the process in an assign activity.

When a process is deployed, each role defined in a partner link is assigned an endpoint reference. An

endpoint

indicates a specific location for accessing a Web service using a specific protocol and data format. An

endpoint reference

conveys the information needed to access a Web service endpoint. Using endpoint references in deployment makes possible the dynamic selection of a service partner.

Within a process, you can invoke a service by setting a target endpoint reference in an assign activity. For more information, see Assign. Also, a partner link can be declared within the process or within a scope activity. For more information, see Scope.