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Abstract

In this paper, main components of a workflow system that are relevant to the correctness in the presence of concurrency are formalized based on set theory and graph theory. The formalization which constitutes the theoretical basis of the correctness criterion provided can be summarized as follows: • Activities of a workflow are represented through a notation based on set theory to make it possible to formalize the conceptual grouping of activities. • Control-flow is represented as a special graph based on this set definition, and it includes serial composition, parallel composition, conditional branching, and nesting of individual activities and conceptual activities themselves. • Data-flow is represented as a directed acyclic graph in conformance with the control-flow graph. The formalization of correctness of concurrently executing workflow instances is based on this framework by defining two categories of constraints on the workflow environment with which the workflow instances and their activities interact. These categories are: • Basic constraints that specify the correct states of a workflow environment. • Inter-activity constraints that define the semantic dependencies among activities such as an activity requiring the validity of a constraint that is set or verified by a preceding activity. Basic constraints graph and inter-activity constraints graph which are in conformance with the control-flow and data-flow graphs are then defined to represent these constraints. These graphs are used in formalizing the intervals among activities where an inter-activity constraint should be maintained and the intervals where a basic constraint remains invalid. A correctness criterion is defined for an interleaved execution of workflow instances using the constraints graphs. A concurrency control mechanism, namely Constraint Based Concurrency Control technique is developed based on the correctness criterion. The performance analysis shows the superiority of the proposed technique. Other possible approaches to the problem are also presented.

Design and Implement of Dynamic Context-Aware Monitoring System Based on OWL

“…3) cycle-driven global coordination This mechanism only carries out dynamic coordination algorithm when manufacturing process has getting into the coordination cycle set up in advance or all of event-driven coordination mechanism cannot put the production task into effect according to its original plan [4,5] .…”

From Cowardice to Illness: Diagnosing Malingering in the Ottoman Great War

“…Dr Hayrettin Arpınar relates that in order to avoid leaving behind evidence, some 'malingerers made a cast from bread dough for their whole hand in order to hide burn and powder marks'. 53 The dough absorbed any evidence that might be left behind. And when it was removed, the hand was clean of burn marks except for the bullet hole or the missing finger.…”

“…Dr Hayrullah Diker put their opinions well: '[The malingerer is an actor], the kind of actor who is also the author of his own role.' 58 As much as the neuropsychiatrists were concerned with the possibility of educated malingerers fooling non-specialist battalion doctors, they also dreaded the possibility of misdiagnosis in the other direction, where real epileptics, or otherwise sickly men, were diagnosed as malingerers and punished. 59 Since the illiterate and 'unintelligent' malingerers easily confessed to their simulation, the educated malingerers required more effort from the neuropsychiatrist.…”

Decentralized Communication for Data Dependency Analysis Among Process Execution Agents

“…Workflow Management Systems typically provide exception handlers to support backward and forward recoveries (Chiu, Li, & Karlapalem, 2000;Hagen & Alonso, 2000;Kiepuszewski Muhlberger, & Orlowska, 1998). The difficulty of achieving correctness in workflow management, especially with respect to data consistency issues, is outlined in Kamath and Ramamritham (1996) and Arpinar, Halici, Arpinar, and Dogac (1999). More recently, the work in Lu (2002) and Lu, Bernstein, and Lewis (2006) describes techniques for formalizing the semantics of workflows, checking the correctness of workflows, and automatically generating workflow specifications.…”