The three core components of BPEL are the:
• BPEL Designer
• Process flow template
• BPEL Engine
In a typical BPEL scenario, a business expert/analyst of a company would use the BPEL Designer (a Graphical User Interface) and define the business process. A business process, for example, could be a 'Purchase Order' business scenario. Web services needed for this scenario would be included in the flow that uses the designer. Once the business expert defines the business process flow, a process logic template containing the process flow logic would be generated by the Designer in the background. At runtime, this process template would be executed by the BPEL Engine.
A Graphical User Interface is used to define a business process that would be independent of the underlying applications. It is intuitive for the Business experts to define the process without being overly technical in depth. It generates the BPEL process flow logic template.
Process flow template
The process flow format adheres to the BPEL specification. It captures the business process flow logic. It is generated from the BPEL designer at design time and executed by the BPEL Engine at runtime. Following is a sample process flow template for a HelloWorld Web service invocation.