For an easy way to create and use partner link types and partner links, see

What are Participants?

A BPEL process describes a flow of interactions between the process and services. Each interaction describes what role the process and services play at that step in the flow and what data can be manipulated by the parties in those roles.

BPEL defines constructs to identify roles and relationships used in interactions.

The constructs are partner link and partner link type. A partner link describes the roles that a process and service play as well as what data they can manipulate in that role. A partner link is defined by its partner link, as shown in the following diagram.

The partner definitions and usage in a BPEL process do not refer to the specifics of Web services. Since a BPEL process is a reusable definition that can be deployed in different ways, the definitions are abstract. The addressing, security, and other specifics of Web services are taken care of at deployment time. When a process is deployed, every partner role in a partner link for a BPEL process instance is assigned a unique endpoint reference.