Managing Evolving Business Workflows through the Capture of Descriptive Information

Business systems these days need to be agile to address the needs of a changing world. In particular the discipline of Enterprise Application Integration requires business process management to be highly reconfigurable with the ability to support dynamic workflows, inter-application integration and process reconfiguration. Basing EAI systems on model-resident or on a so-called description-driven approach enables aspects of flexibility, distribution, system evolution and integration to be addressed in a domain-independent manner. Such a system called CRISTAL is described in this paper with particular emphasis on its application to EAI problem domains. A practical example of the CRISTAL technology in the domain of manufacturing systems, called Agilium, is described to demonstrate the principles of model-driven system evolution and integration. The approach is compared to other model-driven development approaches such as the Model-Driven Architecture of the OMG and so-called Adaptive Object Models. 1. Background and Related Works As the global marketplace becomes increasingly complex and intricately connected, organizations are constantly pressured to re-organize, re-structure, diversify, consolidate and slim down to provide a winning competitive edge. With the advent of the Internet and e-commerce, the need for coexistence and interoperation with legacy systems and for reduced ’times-to-market’, the demand for the timely delivery of flexible software has increased. Couple to this the increasing complexity of systems and the requirement for systems to evolve over potentially extended timescales and the importance of clearly defined, extensible models as the basis of rapid systems design becomes a pre-requisite to successful systems implementation. One of the main drivers in the object-oriented design of information systems is the need for the reuse of design artefacts or models in handling systems evolution. To be able to cope with system volatility, systems must have the capability of reuse and to adapt as and when necessary to changes in requirements. The philosophy that has been investigated in the research reported in this paper is based on the systematic capture of the description of systems elements covering multiple views of the system to be designed (including processes and workflows) using common techniques. Such a description-driven approach [1, 2] involves identifying and abstracting the crucial elements (such as items, processes, lifecycles, goals, agents and outcomes) in the system under design and creating high-level descriptions of these elements which are stored and managed separately from their instances. Description-driven systems (DDS) make use of so-called meta-objects to store domain-specific system descriptions that control and manage the life cycles of metaobject instances or domain objects. The separation of descriptions from their instances allows them to be specified and managed and to evolve independently and asynchronously. This separation is essential in handling the complexity issues facing many web-computing applications and allows the realization of inter-operability, reusability and system evolution as it gives a clear boundary between the application's basic functionalities from its representations and controls. In a description-driven system as we define it, process descriptions are separated from their instances and managed independently to allow the process descriptions to be specified and to evolve asynchronously from particular instantiations of those descriptions. Separating descriptions from their instantiations allows new versions of elements (or element descriptions) to coexist with older versions. In this paper the development of Enterprise Resource Planning (ERP) in flexible business systems is considered and the need for business process modelling in Enterprise Application Integration (EAI) [3] is established. Workflow systems are considered as vehicles in which dynamic system change in EAI can be catered for as part of handling system evolution through the capture of system description. A description-driven approach is proposed to enable the management of workflow descriptions and an example is given of an application of the CRISTAL descriptiondriven system developed at CERN [4] to handle dynamic system change in workflows. This approach has today two parallel implementations that are called CRISTAL for CMS and Agilium. The two applications are based on the same kernel called CRISTAL KERNEL which provides the DDS functionalities. Both applications inherit these functionalities even if the goals and the specifics of each application is radically different. 2. The Need for Integrated Business Process Modelling in EAI In recent years, enterprises have been moving from a traditional function-led organisation, addressing the needs of a “vertical” market, to a “horizontal” organisation based on business processes. The emergence of new norms such as the ISO 9001 V2000 and the development of inter-enterprise exchanges are further drivers towards process-led reorganisation. However, currently available information systems and production software are still organised following function models. Consequently, they are not well adapted to the exchange of information between enterprises nor to coping with evolving process descriptions. In modern enterprises organised following a horizontal structure, industrial EAI solutions are very dependent on process performance and on the ability of the underlying enterprise management to execute and automate the business processes. Furthermore the requirement for the support of enterprise activities is not only for the execution of internal processes but also for external processes, as in the support of suppliercustomer relationships especially in supply chain management. Enterprise processes have to integrate increasingly more complex business environments including domain-dependent processes for managing both interapplication operation and inter-organisation operation where efficient communications is crucial. Integration sources across enterprises are numerous and multi-technological and can include ERP, human resource management, Customer Relation Management (CRM), administration software, Intranet /Internet, proprietary software and a plethora of office tools. The first step that an enterprise must make in order to move from a standard vertical organisation to a horizontal organisation is to chart its existing business processes and the interactions between these processes. Following this it must update and manage its internal processes based on existing information systems. For that, the enterprise may be confronted by a collection of different production software systems and their abilities to interact. Most of the software offerings that support ERP deal with the description of enterprises through its organisation by function and examples of these products include systems for purchase service, stock management, production management etc. However individual systems need to synchronise with each other and each normally has their own process management models. Most commercial software do not provide tools to aid in process description and evolution. Even when workflow engines (which can provide synchronisation between systems) are integrated within ERP systems, they are for the most part not synchronised with external applications of the ERP system. EAI [3] systems concentrate on an architecture centred on software which is dedicated to the interconnection of heterogeneous applications that manage information flows. The heart of EAI software is normally based on the concept of interface references where transformation, routing and domain dependent rules are centralised. Standard EAI architecture is normally built on three layers: processes, routing and transport layers as shown in figure 1.