Essential Business Process Modeling

The Business Process Modeling Initiative (BPMI, http://www.bpmi.org) is a nonprofit organization whose mission is to build standards and a common architecture for BPM. BPMI, started by Intalio in 2000, has grown to include a variety of organizations, including BEA, Fujitsu, IBM, IDS Scheer, Pegasystems, PeopleSoft, SAP, SeeBeyond, Tibco, Virtria, and WebMethods.

BPMI is itself a member of several key organizations, including W3C, OASIS, OMG, and the WfMC. Through these memberships, BPMI is able to contribute to discussion of essentially every current BPM standard whose specification the BPMI does not itself own: BPEL with OASIS; choreography with W3C; business process metamodels with OMG; and XPDL, WAPI, WfXML, and the workflow reference model with WfMC.

BPMI's contribution focuses on the following functional specifications:

Business Process Modeling Notation

BPMN is a graphical flowchart language that can be used by business analysts or developers to represent a business process in an intuitive visual form. Stephen White of IBM wrote Version 1.0 of the specification in 2004.

Business Process Modeling Language

BPML is an XML language that encodes the flow of a business process in a form that can be interpreted by a process execution engine. Assaf Arkin of Intalio wrote version 1.0 of the BPML specification, which was published in November 2002.

Business Process Query Language

BPQL is a standardized administration and monitoring query language for business processes, intended as a foundation for business activity monitoring (BAM) . The initial public version of BPQL has not yet been published.

Business Process Semantic Model

The OMG has proposed a BPDM, or a common model for all business process models, whose definition is based on the OMG Meta-Object Facility (MOF) foundation. BPSM, not yet published, is the BPMI's putative BPDM metamodel. (For more information on BPDM and MOF, see Chapter 9.)

Business Process Extension Layers

BPXL is a standard set of BPEL extensions for transactions, business rules, task management, and human interaction. The BPXL specification has not yet been published.

These specifications do not exist in isolation; they are pieces of BPMI's recommended BPM stack (documented in the BPMI's current material at http://www.bpmi.org), as shown in Figure 6-1.

At the top of the stack is the visual process design layer, based on BPMN. Below it is BPSM, in which BPMN visual models are represented in a common, interchangeable metamodel form, suitable for import into the execution layer based on the OASIS group's BPEL (discussed in Chapter 5), which is extended by BPXL. BPEL, in turn, runs atop a web services messaging and transport layer, whose major standards include the W3C's WSDL and the OASIS UDDI . BPEL shares the web services base with the standard BAM query service BPQL, as well as the W3C's WS-CDL choreography (discussed in Chapter 8). BPQL enables business monitoring of BPEL processes, and WS-CDL defines the global contract governing the partner interactions of BPEL processes.

This stack is intriguing for several reasons:

• Not all pieces are based on BPMI standards. (The BPMI pieces are shaded.) BPMI embraces standardssuch as BPEL, WS-CDL, and the core web services standardsof other organizations.

• Some of the BPMI pieces (dotted in the figure) are not currently published. If the stack were to be implemented today, the implementers would need to find suitable substitutes for BPSM, BPXL, and BPQL.

• BPML is nowhere to be found! Its placethe web service-based execution spotseems to have to been stolen by BPEL. The BPMI position paper^[*] concedes that the BPEL standard, BPML's most formidable competitor, has won the XML execution language war, and by virtue of "might makes right" is a better fit than BPML for the stack.

  ^[*] BPMI, "BPMN and BPEL4WS: A Convergence Path Toward a Standard BPM Stack," http://www.bpmi.org, August 2002.

• The same BPMI position paper recommended Web Services Choreography Interface (WSCI) as the choreography piece, but since then BPMI has adopted WS-CDL, the W3C's official approach.

This chapter describes BPMN and BPML in detail and introduces the main aspects of each language through several feature-rich examples; each language is also rated on its support for the P4 patterns introduced in Chapter 4.^[*]

^[*] Interestingly, the BPMN specification provides a BPEL mapping, which facilitates BPEL XML representation of BPMN diagrams; this mapping is explored at a high level later in the chapter. The BPMN specification makes no mention of BPML, though one would expect a BPMN-to-BPML mapping to resemble the BPMN-to-BPEL mapping.