Accessing a Service Interface from a Composite Conversation
A service interface is described by a composite conversation that represents an information exchange channel between architecture components.

A Service Interface is a template of a contract between entities (organizational, IT …). The contract is described by available operations which can be triggered trough messages exchanged by roles (vendor, buyer..).

A composite conversation is described by an service contract. This service interface contains service operations or sub-service interfaces.
To create a composite conversation:
1. In the diagram insert toolbar, click the
Composite Conversation 
button.
2. Draw a link between the two entities in communication.
3. In the creation window, precise the name of the conversation and select the service interface you want to use.
4. Click OK.