Dynamics of process models in PML

Abstract

The IPSE 2.5 project is concerned with the problem of how computer systems can be used in the development of information systems.The project is being carried out under the UK Alvey Programme Software Engineering Strategy by a consortium comprising STC Technology Limited, International Computers Limited, University of Manchester, Dowty Defense and Air Systems Limited, SERC Rutherford Appleton Laboratories, Plessey Research Roke Manor Ltd. and British Gas plc. Praxis Systems has worked as a subcontractor to STC and ICL. It finishes at the end of 1989.The project is concerned to provide facilities in support of people and organisations engaged in all aspects of computer systems development. Of course this is a vast field and thus the project has focussed on “process modelling” and “formal methods”. The former is concerned with coordination of the many processes undertaken in computer systems development. Formal methods are mathematically based approaches to software development.This synopsis (a summary of [1]) of the project emphasises “process modelling”. More details on the Formal Reasoning work of the project can be found in [2].Process Modelling is the act of participating in processes. Each and every member of an IPSE 2.5 community is a process modeller, a programmer, a secretary, the chief programmer, a project manger, a salesperson, the personnel manager, the accountant, etc. Furthermore, the devices of an office environment, printers, fax machines, photocopiers, etc., each perform roles in the office environment, and thus each of these is a process modeller. This view has the important property that a Process Modelling Language must be 'reflective' so that anything which has a purpose and place in a process model can be introduced in terms of the objects which are already supported in the language.Modelling actions include: creating abstract processors — roles; defining role behaviours — Role Classes; defining inter and intra-role behaviours; instigating inter-role interactions; selecting agenda actions; performing selected actions.The IPSE 2.5 project supports process modelling through the use of a Process Control Engine (PCE). A PCE can be loaded with knowledge (a process model) of the roles (activities) to be carried out by the staff and tools of the organisation using the PCE and thereafter the PCE can control the progress of the organisation's processes; coordinating, aiding, enforcing, and triggering the desired actions between the organisations processing resources — they thus cooperate in a meaningful fashion and work at a balanced rate.The Process Modelling Language (PML) is used to interact with the PCE and hence to 'load' process model fragments. PML development is based on work reported in [3]. A process model provides an appropriate context for each of the resources of a project to undertake the work ascribed to them and hence to enable development of a system.A further objective of the project has been the integration of Managerial and Technical procedures to enable controlled development of software systems using extant and new methodologies. The project focussed on the basic goal satisfaction (or planning) cycle of analyse the goal, create plan of action, resource and activate, monitor and revise actions. An important aspect of this approach is that revision constitutes 'Process Model Evolution' — a new behaviour!The project has spent some time on the challenging problem and implications of dynamic bindings and scoping of process model changes. In studying these problems the project developed models of a Mini-company with three management levels of Board, Business Centre, Project. Business Centres sell software services and as a result start projects. The projects employ their own chosen technical methods, but report as directed from the business centre, which in turn reports to the board. Much of the reporting is automated, and ensures timely and accurate reports of progress, accounting details, and specific items included on per project or business centre basis. Staff may also be supplied semi-automatically through prompting for resourcing as and when the need arises.IPSE 2.5 work has also used the above mentioned technology in the development of prototype IPSEs to support Formal (OBJ/Malpas) and Informal (SSADM like methods) development methods.The project is now progressing on the evaluation of both Formal Reasoning IPSE (MURAL), and the Demonstrator PCE. These evaluations will be reported as part of the project deliverables to Alvey.