Dynamic Change of Server Assignments in Distributed Workflow Management Systems

Workow management systems (WfMS) offer a promising approach for realizing process-oriented information systems. Central WfMS, with a single server controlling all workow (WF) instances, however, may become overloaded very soon. In the literature, therefore, many approaches suggest using a multi-server WfMS with distributed WF control. In such a distributed WfMS, the concrete WF server for the control of a particular WF activity is usually dened by an associated server assignment. Following such a partitioning approach, problems may occur if components (WF servers, subnets, or gateways) become overloaded or break down. As we know from other elds of computer science, a favorable approach to handle such cases may be to dynamically change hardware assignment. This corresponds to the dynamic change of server assignments in WfMS. This paper analyses to what extend this approach is reasonable in such situations

Dealing with Forward and Backward Jumps in Workflow Management Systems

Workflow management systems (WfMS) offer a promising technology for the realization of process-centered application systems. Adeficiency of existingWfMSis their inadequate support for dealing with exceptional deviations from the standard procedure. In the ADEPT project, therefore, we have developed advanced concepts for workflow modeling and execution, which aim at the increase of flexibility in WfMS. On the one hand we allow workflow designers to model exceptional execution paths already at buildtime provided that these deviations are known in advance. On the other hand authorized users may dynamically deviate from the pre-modeled workflowat runtime as well in order to deal with unforeseen events. In this paper, we focus on forward and backward jumps needed in this context. We describe sophisticated modeling concepts for capturing deviations in workflow models already at buildtime, and we show how forward and backward jumps (of different semantics) can be correctly applied in an ad-hoc manner during runtime as well. We work out basic requirements, facilities, and limitations arising in this context. Our experiences with applications from different domains have shown that the developed concepts will form a key part of process flexibility in process-centered information systems

Guaranteeing Soundness of Configurable Process Variants in Provop

Usually, for a particular business process a multitude of variants exists. Each of them constitutes an adjustment of a reference process model to specific requirements building the process context. While some progress has been achieved regarding the configuration of process variants, there exists only little work on how to accomplish this in a sound and efficient manner, especially when considering the large number of process variants that exist in practice as well as the many syntactical and semantical constraints they have to obey. In this paper we discuss advanced concepts for the context- and constraint-based configuration of process variants, and show how they can be utilized to ensure soundness of the configured process variants. Enhancing process-aware information systems with the capability to easily configure sound process models, belonging to the same process family and fitting to the given application context, will enable a new quality in engineering process-aware information systems

Context-based Configuration of Process Variants

When designing process-aware information systems, usually, variants of the same process type have to be defined and maintained. Each of these process variants constitutes an adjustment of the same process to specific requirements building the variant context. Current business process management tools do not support the context-based definition and configuration of such variants in an adequate manner. Instead, each process variant has to be defined from scratch and be kept in a separate model. This results in considerable redundancies when modeling and adapting process variants, and is also a time consuming and error-prone procedure. This paper presents a more flexible and context-based approach for configuring and managing process variants. In particular, we allow for the configuration of process variants by applying a context-dependent set of well-defined change operations to a base process

Capturing Variability in Business Process Models: The Provop Approach

Usually, for a particular business process different variants exist. Each of them constitutes an adjustment of a reference process model to specific requirements building the process context. Contemporary process management tools do not adequately support the modeling of such process variants. Either the variants have to be specified as separate process models or they are expressed in terms of conditional branches within the same process model. Both methods often lead to redundancies making model adaptations a time consuming and error-prone task. In this paper we discuss selected concepts of the Provop approach for modeling and managing process variants. A particular process variant can be configured at a high level of abstraction by applying a set of well-defined change operations to a reference process model. In particular, this paper discusses advanced concepts for the design and modeling of such a reference process model as well as for the adjustments required to configure the different process variants. Altogether, Provop provides a flexible and powerful solution for process variant management

Lifecycle Management for Business Process Variants

This chapter deals with advanced concepts for the configuration and management of business process variants. Typically, for a particular business process, different variants exist. Each of them constitutes an adjustment of a master process (e.g., a reference process) to specific requirements building the process context. Contemporary Business Process Management tools do not adequately support the modeling and management of such process variants. Either the variants have to be specified in separate process models or they are expressed in terms of conditional branches within the same process model. Both methods can result in high model redundancies, which make model adaptations a time-consuming and error-prone task. In this chapter, we discuss advanced concepts of our Provop approach, which provides a flexible and powerful solution for managing business process variants along their lifecycle. Such variant support will foster more systematic process configuration as well as process maintenance

Casimir Energy in Deconstruction and the Cosmological Constant

We demonstrate that by employing the correspondence between gauge theories in geometric and in deconstructed extra dimensions, it is possible to transfer the methods for calculating finite Casimir energy densities in higher dimensions to the four-dimensional deconstruction setup. By this means, one obtains an unambiguous and well-defined prescription to determine finite vacuum energy contributions of four-dimensional quantum fields which have a higher-dimensional correspondence. Thereby, large kink masses lead to an exponentially suppressed Casimir effect. For a specific model we hence arrive at a small and positive contribution to the cosmological constant in agreement with observations.Comment: 38 pages, 5 figures, minor changes in the text, results unchanged, figure added, reference adde

Improving the Quality and Cost-effectiveness of Process-oriented, Service-driven Applications: Techniques for Enriching Business Process Models

A key objective of any Service-driven architectural approach is to improve the alignment between business and information technology (IT). Business process management, service composition, and service orchestration, play major roles in achieving this goal. In particular, they allow for the process-aware integration of business actors, business data, and business services. To optimize business-IT alignment and to achieve high business value, the business processes implemented in process-aware information systems (PAISs) must be defined by domain experts, and not by members of the IT department. In current practice, however, the information relevant for process execution is usually not captured at the required level of detail in business process models. In turn, this requires costly interactions between IT departments and domain experts during process implementation. To improve this situation, required execution information should be captured at a sufficient level of detail during business process design (front-loading). As another drawback, existing methods and tools for business process design do not consider available Service-oriented Architecture (SOA) artifacts such as technical service descriptions during process design (look-ahead). Both front-loading and look-ahead are not adequately supported by existing business process modeling tools. In particular, for many process aspects, appropriate techniques for specifying them at a sufficient level of detail during business process design are missing. This chapter presents techniques for enabling front-loading and look-ahead for selected process aspects and investigates how executable process models can be derived from business process models when enriched with additional information

Correct Configuration of Process Variants in Provop

When engineering process-aware information systems (PAISs) one of the fundamental challenges is to cope with the variability of business processes. While some progress has been achieved regarding the configuration of process variants, there exists only little work on how to accomplish this in a correct manner. Configuring process variants constitutes a non-trivial challenge when considering the large number of process variants that exist in practice as well as the many syntactical and semantical constraints a configured process variant has to obey in a given context. In previous work we introduced the Provop approach for configuring and managing process variants. This paper picks up the Provop framework and shows how it ensures correctness of configurable process variants by construction. We discuss advanced concepts for the context- and constraint-based configuration of process variants, and show how they can be utilized to ensure correctness of the configured process variants. In this paper we also consider correctness issues in conjunction with dynamic variant re-configurations. Enhancing PAISs with the capability to correctly configure process models fitting to the given application context, and to correctly manage the resulting process variants afterwards, will enable a new quality in PAIS engineering

Issues in Modeling Process Variants with Provop

For a particular business process, typically, different variants exist. Each of them constitutes an adjustment of a basic process (e.g. a reference process) to specific requirements building the process context. Contemporary business process management (BPM) tools, however, do not adequately support the modeling and management of process variants. Either the variants have to be specified by separate process models or they are expressed in terms of conditional branches within the same process model. Both methods can lead to high model redundancies, which make model adaptations a time consuming and error-prone task. In this paper we discuss advanced modeling concepts of our Provop approach, which provides a flexible and powerful solution for modeling and managing process variants. With Provop, a particular process variant can be configured at a high level of abstraction by applying a set of well-defined change operations to a basic process model