1 Multi-Agent Transactions for Web-based Design Activities Muhammad Younas, Kuo-Ming Chao, Rachid Anane, Anne James Data and Knowledge Engineering Research Group (DKERG) School of Mathematical and Information Sciences, Coventry University, UK {m.younas, k.chao, r.anane, a.james}@coventry.ac.uk Abstract Web-based engineering design activities require fault tolerance and concurrent access to shared resources such as databases and Web servers. Such activities are generally dynamic, cooperative, long-lived, interactive, and non-prescriptive. We propose a new multi-agent transaction model, which is based on extended transactions and multi-agent technologies. The novelty of this model is that it automatically customises transactions to the requirements of the design activities. In addition, this model is believed to improve concurrency and fault tolerance, facilitate interaction and co-operation of participating systems involved in design activities. 1. Introduction Complex engineering design (e.g., offshore oil platforms, aeroplanes, ships) requires collaborative work among diverse design disciplines. Such design environments often involve a number of different organisations that specialise in different design disciplines, which are distributed across the network. The Web, an emerging design environment, provides an infrastructure for design activities to be geographically distributed among different teams and design systems. In such highly dynamic environment the nature of the work and the requirements may change continuously. More importantly, these activities require consistent and concurrent access to shared resources (e.g., databases, Web servers, etc.) and also require fault tolerance. This motivates the need for providing suitable techniques to facilitate this kind of cooperative activities. Existing design approaches apply Extended Transaction Models (ETM) to design activities [8, 15, 6]. ETM relax isolation and atomicity properties of the ACID (atomic, isolated, consistent, durable) transactions [5]. ETM are used to provide design activities with concurrency and consistency aspects. However, one of the major problems with current ETM systems is the decision- making. For instance, it is difficult to determine where to split and join transactions, or where to compensate or replace transactions. Similarly, multi-agents are also used in the design activities [13, 12]. The role of agents in design activities is to support communication and to improve the co- ordination among design systems. However, transaction- like facilities (e.g., ensuring concurrent and consistent access to shared resources [9]) are not well addressed in multiple design agent systems. Our research identifies that the exclusive use of one of the above technologies (i.e., transactions and multi- agent) remains ineffective in the design activities. In this paper we aim to develop a new model that addresses the issues of Web-based design activities by combining multi- agent technology with ETM. One distinguishing feature of the proposed model is that it provides a facility for automatically customising a variety of ETM to the requirements of design activities. Existing approaches [6, 15, 1] require users to specify transaction models to suit their needs. In addition, the proposed model is believed to improve concurrency and fault tolerance, facilitate interaction and co-operation of participating systems. The paper is structured as follows. Section 2 identifies requirements of the design activities. Section 3 reviews current approaches and establishes their limitations to design activities. Section 4 formally specifies our proposed model. Finally, section 5 concludes the paper. 2. Requirements The requirements are based on the characteristics of designing large and complex engineering products (e.g., offshore oil platforms, aeroplanes, ships). Such environments often involve a number of different organisations that specialise in different design