CiAN: A Workﬂow Engine for MANETs Rohan Sen, Gruia-Catalin Roman, and Christopher Gill Department of Computer Science and Engineering Washington University in St. Louis Campus Box 1045, One Brookings Drive, St. Louis, MO 63130, U.S.A. {rohan.sen,roman,cdgill}@wustl.edu Abstract. The practice of using workﬂows to model complex activities in stable networks is commonplace and is supported by many commer- cially available workﬂow management systems (WfMSs). However, the use of workﬂows to model collaborative activities in mobile environments, while possible at the model level, has not gained traction due to the lack of a suitable WfMS for mobile networks and devices. This paper seeks to address this need. We present CiAN, a choreography-based workﬂow engine that is designed with MANETs in mind. We describe the de- sign, architecture, and communication protocols used by CiAN as well as its implementation using Java. An evaluation of the communication protocol used to coordinate among various workﬂow participants across MANETs is also presented. 1 Introduction Workﬂows can be conceptualized as a set of related tasks that are arranged ac- cording to a speciﬁc order and structure to accomplish a higher level goal in a collaborative manner. Workﬂows are commonly represented and speciﬁed in terms of graphs or petri-nets [23]. Software systems that execute these workﬂow speciﬁcations are called Workﬂow Management Systems (WfMSs). In the current state of the art, WfMSs such as ActiveBPEL [9], Oracle Workﬂow Engine [18], Biztalk [7], etc. operate across wired networks and execute workﬂows that en- code complex business processes such as insurance claims processing, inventory control, loan approvals, among others. A WfMS has two main functions: assigning tasks in the workﬂow to suitable hosts and subsequently invoking them in the correct order, passing any data or notiﬁcations between them as necessary. The performance of all the tasks by multiple participants collectively accomplishes the collaborative activity speci- ﬁed by the workﬂow. Current designs for WfMSs reﬂect the stable and reliable environment in which they operate. The architecture of these systems are cen- tralized and interactions with the various distributed components are typically synchronous calls made “just-in-time”. In this paper, we describe the design of a WfMS targeted to mobile settings. Our work is motivated by the fact that while the workﬂow model is robust enough to describe more expansive forms of collaborations (including collabo- rations involving both humans and software in the physical world), it is not in D. Lea and G. Zavattaro (Eds.): COORDINATION 2008, LNCS 5052, pp. 280–295, 2008. c  Springer-Verlag Berlin Heidelberg 2008