An Introduction to BPEL standard and its extentions - SoberIT

BPEL ProcessBPEL ProcessBPEL ProcessBPEL ProcessPeopleActivityPeopleActivityPeopleActivityPeopleActivityInlineHumantaskInlineHuman taskStandaloneHuman taskCallableWSDLInterfaceHTProtocolInterfaceStandalone HumantaskFigure 3.1: Interaction patterns between process and task [15]In Pattern 1, the task is specified inline within a People activity. In Pattern 2, the task is specified inlinewithin the BPEL process. In both patterns, the task automatically shares process context and data.In Pattern 3, the task is defined externally to the process without a specific interface, In that wayapplication vendors can expose their functionality as tasks which can be called from BPEL processengines.Pattern 4 is like 3 except that the task interface is specified using a callable WSDL, which is invokedusing Web services. Moreover, WS-HumanTask is used for communication between process and task.4. WS-BPEL 2.0 EXTENSIONS FOR SUB-PROCESSES – BPEL-SPE4.1 Demand for BPEL -SPEBesides excluding people action, BPEL does not support the explicit definition of business “fragments”that can be invoked from another (or the same) business process either [16]. In both the BPEL4WS 1.1and the WS-BPEL 2.0 specifications,, the only way to simulate this behavior is to define a completebusiness process as an independent service and invoke it via invoke activity. However, sub-process iscompletely hidden from its parent process, namely it does not have lifecycle coordination with its parentprocess.4.2 Development of BPEL-SPEIn September 2005, IBM and SAP published a white paper called Extensions for Sub-Processes (BPEL-SPE). The paper calls for the explicit definition of sub-processes, allowing for the reuse of the subprocess,tight coupling of the sub-process's lifecycle with its parent process, and the ability of the subprocessto access its parent processes data [16]. The language specification defining the precise syntaxand semantics will be published in the future.