The array of standards for defining application workflow and business processes can be confusing. Here, eWEEK Labs offers a guide to navigating the sea of acronyms and abbreviations.
The WfMC (Workflow Management Coalition), established in 1993, initiated many of the workflow and BPM (business process management) standards efforts. With more than 300 members, the coalition extends beyond vendors to customers, consultants and academic institutions.
The WfMC defines two standards for interfaces for workflow services: XPDL (XML Process Definition Language) and Wf-XML 2.0, or Workflow-XML.
An XML schema, XPDL specifies process definitions so that they can be interchanged across applications. XPDL describes a minimum metamodel—essentially, the objects and related attributes described in a process definition—and abstracts specific attributes in a generic way.
Two applications that are XPDL-compliant wont necessarily be able to fully exchange XPDL data, however. Attributes outside the core metamodel can include vendor-specific definitions that another tool doesnt understand or that can describe a vendor-specific feature.
Wf-XML 2.0 is a way to integrate process engines over the Internet or an intranet through the proposed ASAP (Asynchronous Service Access Protocol), an extension to SOAP (Simple Object Access Protocol) that can monitor and control an asynchronous Web service through XML.
ASAP provides a means for remotely starting and stopping a process engine. However, it doesnt provide a way to see into the process definition itself to monitor the process. Nor can ASAP provide a view of which activities have been completed or must be completed before the activity can continue.
Wf-XML bridges these gaps by providing observer, factory and activity resources for Web services. The observer gives a service a way to communicate data about events. Factories are the process-definition resources within a process engine. The activity resource is the part of the process execution in which the Web service is waiting for an action, be it a human or machine action, to complete.
OASIS (Organization for the Advancement of Structured Information Standards), another standards body, is working on defining XML schema for application-to-application integration. Its UBL (Universal Business Language) standard, also ratified last November, is a subset of features within ebXML (electronic business XML). ebXML defines a metamodel for connecting the business systems of trading partners.
UBL defines a generic XML format for interchanging business documents such as invoices, purchase orders and shipping notices. Rather than defining industry-specific terms for these documents, UBL provides leeway for companies with specific relationships to define their own terms with XML.
BPEL4WS 1.1 (Business Process Execution Language for Web Services) results from a collaborative effort among BEA Systems Inc., IBM, Microsoft Corp., SAP AG and Seibel Systems Inc. In April of last year, OASIS began work on extending the BPEL4WS 1.1 standard as WSBPEL (Web Services for BPEL). WSBPEL builds on XLANG and WSDL (Web Services Description Language) to define an XML-based programming language for business processes and business interaction protocols.
BPEL itself gives companies a way to define business processes through partner link types, partner links and endpoint references. Partner link types describe the role each service takes in a given transaction. Partner links are the actual services that complete the business process, and endpoint references mark the communications between two services.
Developed by BEA and IBM, the BPELJ standard unites BPEL and Java programming languages. BPELJ abstracts the partner link types defined within BPEL and WSDL using Java interfaces rather than WSDL ports, giving companies with Java-based applications a way to tap application logic rather than build new sets of Web services.
Technical Analyst Michael Caton can be reached at [email protected].