S. Rinderle-Ma et al. (Eds.): BPM 2009 Workshops, LNBIP 43, pp. 295���304, 2010. �� Springer-Verlag Berlin Heidelberg 2010 HLA/RTI-Based BPM Middleware for Collaborative Business Process Management Byoung Kyu Choi, Duckwoong Lee, and Dong Hun Kang VMS Lab., Department of Industrial & Systems Engineering, KAIST 335 Gwahak-ro, Yuseong-gu, Daejeon 305-701, Republic of Korea {bkchoi,ldw721,donghun.kang}@vmslab.kaist.ac.kr Abstract. Business processes in global economy need closer collaboration with partner enterprises and there is a growing need for BPM systems to support col- laborative business processes. Previous researches on collaborative BPM have some shortcomings and there remains a gap between the demand and supply for collaborative BPM. This paper presents a mediator-based collaborative BPM (CBPM) framework together with a CBPM middleware implementing the CBPM framework. The CBPM middleware is built around the HLA/RTI (high level architecture/run time infrastructure) which is the de facto standard in modeling & simulation. Distinctive features of the proposed CBPM middleware include (1) it covers all workflow interoperability models specified by Work- flow Management Coalition (WfMC), (2) it has a hub architecture allowing scalability and generality, (3) all interoperation messages are handled by a set of standard APIs of WfMC and of HLA/RTI so that anyone who is familiar with those APIs can easily implement the middleware. Keywords: Workflow interoperability, collaborative BPM middleware, HLA/RTI, collaborative object model. 1 Introduction A workflow management system (WfMS) defines and automatically executes work- flows in order to manage the actual flow of work so that the right work is done at the right time with the right information by the right person in the organization [1]. Recently, a WfMS used for business process management (BPM) is often called a BPM system, with an emphasis on orchestrating operational business processes that are driven by explicit process designs. As BPM systems have expanded its coverage to the corporate level and then to the extended enterprise level, the need for workflow interoperability (or collaborative BPM) was recognized by many organizations [2, 3] and researchers [4, 5, 6, 7, 8, 9, 10]. The two terms ���workflow interoperability��� and ���collaborative BPM��� may be used interchangeably. For example, business processes often need to interact with each other, in order to synchronize the execution of their activities, to exchange process data, to request execution of services, or to notify pro- gress in process execution [7].

296 B.K. Choi, D. Lee, and D.H. Kang Standard workflow interoperability models were proposed by Workflow Manage- ment Coalition (WfMC) more than 10 years ago [1, 2]. Recently, a couple of frame- works for collaborative BPM were proposed [9, 10] aiming to realize the workflow interoperability models. However, [9] does not cover the parallel synchronized model and its communication structure is P2P (peer-to-peer), which may hamper its general applicability. Also, [10] has a serverless decentralized (or P2P) architecture and it is an agent-based abstract framework that has yet to be materialized. Therefore, these frameworks have these shortcomings and there remains a gap between the demand and supply for collaborative BPM. This paper aims to fill the gap by presenting a collaborative BPM middleware that is scalable and easy to implement and covers all three workflow interoperability models specified by WfMC. The paper is organized as follows. Section 2 presents our collaborative BPM framework having hub architecture. Key elements of the propose framework are Col- laboration Mediator, Collaboration Planner, Collaboration Manager and COM (col- laboration object model). Section 3 presents a HLA/RTI-based collaborative BPM middleware realizing the proposed framework, followed by an illustrative implemen- tation in the next section. Conclusions and discussions are provided in the last section. 2 Collaborative BPM Framework 2.1 Workflow Interoperability Standard Workflow Management Coalition (WfMC) provides a workflow interoperability standard (Interface 4) for interoperation among different workflow engines [1, 2], in which three types of possible collaboration models (i.e., chained, nested sub-process, parallel synchronized) are specified. Interface 4 provides abstract specifications re- garding the level of interoperability and WfXML-based message format [2, 3, 9]. The three workflow interoperability models are shown in Fig. 1. Fig. 1. Three models of workflow interoperability [1, 2] In the chained model of Fig. 1-(a), an activity of Workflow Engine A simply in- vokes the creation of a process instance in Workflow Engine B. In the nested sub- process model of Fig. 1-(b), an activity of Workflow Engine A invokes the creation of a process instance of Workflow Engine B and waits until the invoked process instance is completed. Finally, in the parallel synchronized model of Fig. 1-(c), a pair of activi- ties (one in Workflow Engine A and the other in Workflow Engine B) is synchronized such that one activity can be completed only when its partner activity is completed as well.