12 . Message Flow Analysis

Message management systems with facilities for the automatic processing of messages can exhibit anomalous behaviour such as infinite loops and deadlock. In this paper we present some methods for analyzing the behaviour of these systems by generating expressions of message flowf rom the procedure specifications. Message domains are partitioned into state spaces, and procedures can be interpreted as automata effecting state changes. Blocking of procedures and procedure loops can then be detected by studying the resulting finite automaton and Petri net representations of message flow. Automatic processing and routing of electronic documents yields some interesting problems when the work that is done with them is sufficiently complicated. In this paper we consider the task of determining what global behaviour is exhibited by messages in a message management system when there exist a number of automatic procedures running at user workstations, examining, processing and routing incoming messages. If the logic built into these procedures is anything but entirely routine, then we may see messages being routed through the system in various ways. If the automatic procedures are adapted from existing manual procedures, there is always a possibility that the translation will be faulty: that messages may get improperly routed, or that procedures will wait indefinitely for messages that do not arrive.W et herefore propose some techniques for studying and analyzing the behaviour that can be expected to result from such automatic procedures. The intended behaviour can thus be verified to some degree, and anomalous behaviour can be detected in advance. In the following section we describe informally the systems that we are interested in modelling and analyzing. Collections of workstations connected by a network are used to pass electronic documents, or "messages". These messages are typically highly-structured, and often resemble forms. Similar messages are classified into "message types". High-levela utomatic procedures may in fact be implemented by the workers using the workstations. Complexactivities can be broken down into simple steps that collect a set of messages satisfying "trigger conditions", perform transformations on those messages, possibly creating or destroying some, and then route or file them. In the third section we introduce a formal model for discussing these systems. The model is then used to develop a characterization of global behaviour in terms of message flow. The message domains (the sets of values that messages may assume) are partitioned into state spaces. Procedures can then be viewed as effecting state transition on …