BPEL processes overview

A business process is a set of business-related activities that are invoked to achieve a business goal.

A BPEL process is a business process that is defined in the Web Services Business Process Execution Language, and comprises the following:

• The activities that are the individual steps within the process. An activity can be one of several different types. Also, an activity can be categorized as either a basic activity or a structured activity.
  • Basic activities are activities that have no structure and do not contain other activities, for example, assign or invoke activities.
  • Structured activities are activities that contain other activities, for example, sequence or while activities.
• The partner links, also known as interface partners or reference partners, that specify the interaction with external partners using WSDL interfaces.
• The variables that store the data that is exchanged with the process and passed between activities.
• Correlation sets that are used to correlate multiple service interactions with the same BPEL process instance. Correlation sets are based on application data that is contained in messages that are exchanged with the process.
• Fault handlers that deal with exceptional situations that can occur when a process runs.
• Event handlers that receive and process unsolicited messages in parallel to the normal process execution.
• Compensation handlers that specify the compensation logic for a single activity, a group of activities, or a scope.

For more information on these constructs, refer to the BPEL specification.

Business Process Choreographer also supports the IBM® extensions to the BPEL language, such as:

• Human task activities for human interaction. These inline to-do tasks can be steps in the process that involve a person, for example, completing a form, approving a document, and so on.
• Script activities for running inline Java™ code. The Java code can access all of the variables, correlation properties, partner links, and process and activity contexts.
• Information service activities to directly access WebSphere® Information Server or relational databases.
• Timestamps for process versioning.
• Extensions for manually setting or controlling the transactional boundaries in a BPEL process.
• Timeouts for activities.