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The lack of flexibility is often seen as an inhibitor for the successful application of workflow technology. Many researchers have proposed different ways of addressing this problem and some of these ideas have been implemented in commercial systems. However, a ˵one size fits all″ approach is likely to fail because, depending on the situation (i.e., characteristics of processes and people involved), different types of flexibility are needed. In fact within a single process/organisation varying degrees of flexibility may be required, e.g., the front-office part of the process may require more flexibility while the back-office part requires more control. This triggers the question whether different styles of flexibility can be mixed and integrated into one system. This paper proposes the Flexibility as a Service (FAAS) approach which is inspired by the Service Oriented Architecture (SOA) and our taxonomy of flexibility. Activities in the process are linked to services. Different services may implement the corresponding activities using different workflow languages. This way different styles of modelling may be mixed and nested in any way appropriate. This paper demonstrates the FAAS approach using the Yawl, Declare, and Worklet services. [ABSTRACT FROM AUTHOR]

BPEL has emerged as the de-facto standard for implementing processes based on web services while formal languages like Petri nets have been proposed as an "academic response" allowing for all kinds of analysis. Although languages such as BPEL and Petri nets can be used to describe service flows, they both tend to "overspecify" the process and this does not fit well with the autonomous nature of services. Therefore, we propose DecSerFlow as a Declarative Service Flow Language. By using a more declarative style, there is no need to overspecify service flows. The declarative style also makes DecSerFlow an ideal language for monitoring web services, i.e., using process mining techniques it is possible to check the conformance of service flows by comparing the DecSerFlow specification with reality. This can be used to expose services that do not follow the rules of the game. This is highly relevant given the autonomous nature of services. [ABSTRACT FROM AUTHOR]

The degree of flexibility of workflow management systems heavily influences the way business processes are executed. Constraint-based models are considered to be more flexible than traditional models because of their semantics: everything that does not violate constraints is allowed. Although constraint-based models are flexible, changes to process definitions might be needed to comply with evolving business domains and exceptional situations. Flexibility can be increased by run-time support for dynamic changes - transferring instances to a new model - and ad-hoc changes - changing the process definition for one instance. In this paper we propose a general framework for a constraint-based process modeling language and its implementation. Our approach supports both ad-hoc and dynamic change, and the transfer of instances can be done easier than in traditional approaches. [ABSTRACT FROM AUTHOR]

Management of dynamic processes in an important issue in rapidly changing organizations. Workflow management systems are systems that use detailed process models to drive the business processes. Current business process modelling languages and models are of imperative nature – they strictly prescribe how to work. Systems that allow users to maneuver within the process model or even change the model while working are considered to be the most suitable for dynamic processes management. However, in many companies it is not realistic to expect that end-users are able to change their processes. Moreover, the imperative nature of these languages forces designer to over-specify processes, which results in frequent changes. We propose a fundamental paradigm shift for flexible process management and propose a more declarative approach. Declarative models specify what should be done without specifying how it should be done. We propose the ConDec language for modelling and enacting dynamic business processes. ConDec is based on temporal logic rather than some imperative process modelling language. Keywords: Workflow management, declarative model specification, dynamic workflow, flexibility, temporal logic. [ABSTRACT FROM AUTHOR]

The need for process support in the context of web services has triggered the development of many languages, systems, and standards. Industry has been developing software solutions and proposing standards such as BPEL, while researchers have been advocating the use of formal methods such as Petri nets and π-calculus. The languages developed for service flows, i.e., process specification languages for web services, have adopted many concepts from classical workflow management systems. As a result, these languages are rather procedural and this does not fit well with the autonomous nature of services. Therefore, we propose DecSerFlow as a Declarative Service Flow Language. DecSerFlow can be used to specify, enact, and monitor service flows. The language is extendible (i.e., constructs can be added without changing the engine or semantical basis) and can be used to enforce or to check the conformance of service flows. Although the language has an appealing graphical representation, it is grounded in temporal logic. Keywords: Service flows, web services, workflow management, flexibility, temporal logic. [ABSTRACT FROM AUTHOR]