The blog explains the One way message integration pattern between the BPEL Process Service Component and external service(s).  The one way message integration pattern approach is also called as ” Fire and Forget message” 

There are scenarios where information need to be sent but it is not of utmost important to send immediately as these are independent actions need to perform once main service has been executed.

One Way message integration pattern example in SOA 12c

Consider an example of the user registration process requires user data validation, business process validation and then submission of user data in the custom user database table. Once the user registration process is completed, user receives the email notification for the confirmation of the user creation process. As user data is already being saved, the email notification service can be invoked once user registration process is completed.
The email notification process is the example of One-way message (or fire and forget) where client application sends the email notification and does not wait for the response.

To implement the one-way message service invocation process, the BPEL Process Service component needs the following
1. The message that client has to send to the target service. To accept the message from the client, the BPEL Process Service component needs a Receive Activity.
2. A Partner link for the target service to which message is to be sent.
3. An Invoke activity to invoke the partner link

Sample for the portType and operation of the BPEL Process WSDL. The WSDL operation includes only input message and No response message is supported.

<wsdl:portType name="OneWayMessageBPELProcess">
<wsdl:operation name="process">
<wsdl:input message="client:OneWayMessageBPELProcessRequestMessage" />
</wsdl:operation>
</wsdl:portType>