An Approach for Supporting Ad-hoc Modifications in Distributed Workflow Management Systems

Supporting enterprise-wide or even cross-organizational business processes is a characteristic challenge for any workflow management system (WfMS). Scalability at the presence of high loads as well as the capability to dynamically modify running workflow (WF) instances (e.g., to cope with exceptional situations) are essential requirements in this context. Should the latter one, in particular, not be met, the WfMS will not have the necessary flexibility to cover the wide range of process-oriented applications deployed in many organizations. Scalability and flexibility have, for the most part, been treated separately in the relevant literature thus far. Even though they are basic needs for a WfMS, the requirements related with them are totally different. To achieve satisfactory scalability, on the one hand, the system needs to be designed such that a workflow instance can be controlled by several WF servers that are as independent from each other as possible. Yet dynamic WF modifications, on the other hand, necessitate a (logical) central control instance which knows the current and global state of a WF instance. For the first time, this paper presents methods which allow ad-hoc modifications (e.g., to insert, delete, or shift steps) to be performed in a distributed WfMS; i.e., in a WfMS with partitioned WF execution graphs and distributed WF control. It is especially noteworthy that the system succeeds in realizing the full functionality as given in the central case while, at the same time, achieving extremely favorable behavior with respect to communication costs

DeWitt Wallace Library Biennial Report 2011-2013

Summary of library activities for 2011-201

Take It To The Bank: How Land Banks Are Strengthening America's Neighborhoods

This report scans the land banking field nationally and reports on the scope and state of this movement. It also includes insights and recommendations for land bank practitioners, based on Community Progress staff members' many collective years of experience working with land banks across the country. There is no land bank model kit. There are, however, common attributes of effective and successful land banks that current and future land bank staff, practitioners, governments, and partner organizations can adopt. This report is intended to help shorten the learning curve

DeWitt Wallace Library Annual Report 2014-2015

Summary of library and media services activities for 2014-201

Evaluation of Correctness Criteria for Dynamic Workflow Changes

The capability to dynamically adapt in-progress workflows (WF) is an essential requirement for any workflow management system (WfMS). This fact has been recognized by the WF community for a long time and different approaches in the area of adaptive workflows have been developed so far. They either enable WF type changes and their propagation to in-progress WF instances or (ad-hoc) changes of single WF instances. Thus, at first glance, many of the major problems related to dynamic WF changes seem to be solved. However, this picture changes when digging deeper into the approaches and considering implementation and usability issues as well. This paper presents important criteria for the correct adaptation of runningw orkflows and analyzes how actual approaches satisfy them. At this, we demonstrate the strengths of the different approaches and provide additional solutions to overcome current limitations. These solutions comprise comprehensive correctness criteria as well as migration rules for change realization

Activity Relations: A Dataflow Approach to Workflow Design

A key step in workflow design is to determine the activity sequences, which are often driven by the dataflow constraints in a business process. Therefore, the literature has suggested that workflow design can start with dataflow analysis. However, no formalism exists for deriving activity sequences from a set of identified activities and their input and output data. In this paper, we formalize the problem of workflow design on the basis of dataflow analysis. We tackle the problem by using the concept of “activity relations” as an intermediate step for identifying the possible activity execution sequences from dataflow. We investigate how to derive activity relations from dataflow and discuss their implication in workflow design

Using Resources as Synchronizers to Manage Mobile Process Adaptation

Process management in Mobile Ad-hoc NETworks (MANETs) has to deal with different types of tasks and resources. Teams can be formed with specific goals, such as recognition of a damaged area for disaster assessment, where each member of a team is assigned some task to be performed according to some policy. However, in real situations, it is possible that task assignments and policies have to be revised due to different causes. In addition to typical causes for dynamic changes in adaptive workflows, mobility introduces some specific problems, e.g. the need for new connectivity-maintaining tasks, or reassignment of tasks originally for members who have become unreachable, or who have no sufficient resources to complete the original plan. As these modifications occur dynamically, it is difficult to manage them through hard-coded programs. Rather, we propose the use of a rule-based formalism, expressed in terms of multi-set rewriting. This supports a resource-centered view, in which both data-dependencies between tasks and plan-dependent ordering of tasks are expressed as production and consumption of resources of different types. In turn, rules are themselves seen as resources, so that they are prone to the same rewriting process, in order to redefine process schemas. The paper illustrates these notions and formalisms, and shows some cases of their application