The partnerLinkType section of the WSDL file (in this example, for LoanService) defines the following characteristics of the BPEL process service component:

• The role (operation) played

• The portType provided for receiving messages within the conversation

Partner link types in asynchronous services have two roles: one for the web service provider and one for the client requester.

In the conversation shown in the following example, the LoanServiceProvider role and LoanService portType are used for client request messages and the LoanServiceRequester role and LoanServiceCallback portType are used for asynchronously returning (calling back) response messages to the client.

<plnk:partnerLinkType name="LoanService">
        <plnk:role name="LoanServiceProvider">
            <plnk:portType name="client:LoanService"/>
        </plnk:role>
        <plnk:role name="LoanServiceRequester">
            <plnk:portType name="client:LoanServiceCallback"/>
        </plnk:role>
    </plnk:partnerLinkType>

Two port types are combined into this single asynchronous BPEL process service component: portType="services:LoanService" of the invoke activity and portType="services:LoanServiceCallback" of the receive activity. Port types are essentially a collection of operations to be performed. For this BPEL process service component, there are two operations to perform: initiate in the invoke activity and onResult in the receive activity.