Understanding the BPEL language framework

BPEL is an XML-based language for creating end-to-end process flow. BPEL is based on the WS-BPEL 2.0 specification and built on the Web Services Description Language (WSDL) 1.1 specifications.

A BPEL process always starts with a process element. A process element must have at least one activity. Activities are the core of the BPEL language framework. Usually a process element also has several attributes. The basic structure of the BPEL code is as follows:

<process name="ncname">
  
<!-- Activities -->
</process>

Every BPEL has activities such as <receive>, <reply>, and <invoke>. Activities describe different action steps in a BPEL process that enable the interaction with external and internal services. Note, that Oracle BPEL also allows interaction with JCA adapters and EDN.

The most important concepts of BPEL are activities, partner links, variables, correlation, and handlers. The BPEL processes expose WSDL interface for consumption as web services. WSDL specifies the location of the service, the operations the service provides, and describes how to access them.