Apache ODE 'executes' or 'runs' one or more business processes which have been expressed in the Web Services Business Process Execution Language (WS-BPEL). It principally communicates with one or more Web services, sending and receiving messages, manipulating data and handling exceptions ('errors') as defined by any given process. The engine is capable of running both long and short living processes to coordinate all the services that make up a service or application (orchestration).

WS-BPEL itself is based upon the XML

XML

Extensible Markup Language is a set of rules for encoding documents in machine-readable form. It is defined in the XML 1.0 Specification produced by the W3C, and several other related specifications, all gratis open standards....

 language and includes a number of ways in which business processes can be expressed. These include conditional clauses, repeating loops, calls to web services and the exchange of messages. Where interfaces with web services are required, it makes use of Web Services Description Language (WSDL) to express them. Messages can be handled in a flexible way by reading either part or all of the message into variables, which can then be used for onward communication.

The engine has two communication layers, with which it interacts with the outside world. :

• Apache Axis2
  Apache Axis2
  Apache Axis2 is a core engine for Web services. It is a complete re-design and re-write of the widely used Apache Axis SOAP stack. Implementations of Axis2 are available in Java and C....
  
   integration layer: supports the communication over Web services.
• Layer based on the JBI standard: supports communication via JBI messages.

Features

• Side-by-side support for both the WS-BPEL 2.0 OASIS
  OASIS (organization)
  The Organization for the Advancement of Structured Information Standards is a global consortium that drives the development, convergence and adoption of e-business and web service standards...
  
   standard and the legacy BPEL4WS 1.1 vendor specification.
• Supports 2 communication layers: one based on Axis2 (Web Services http transport) and another one based on the JBI standard (using ServiceMix).
• Support for the HTTP WSDL binding, allowing invocation of REST
  Rest
  Rest may refer to:* Leisure* Human relaxation* SleepRest may also refer to:* Rest , a pause in a piece of music* Rest , the relation between two observers* Rest , a 2008 album by Gregor Samsa...
  
  -style web services.
• Possibility to map process variables externally to a database table of your choice.
• High level API to the engine that allows you to integrate the core with virtually any communication layer.
• Hot-deployment of your processes.
• Compiled approach to BPEL that provides detailed analysis and validation at the command line or at deployment.
• Management interface for processes, instances and messages.