Using patterns to design rules in workflows

In order to design workflows in changing and dynamic environments, a flexible, correct, and rapid realization of models of the activity flow is required. In particular, techniques are needed to design workflows capable of adapting themselves effectively when exceptional situations occur during process execution. The authors present an approach to flexible workflow design based on rules and patterns developed in the framework of the WIDE project. Rules allow a high degree of flexibility during workflow design by modeling exceptional aspects of the workflow separately from the main activity flow. Patterns model frequently occurring exceptional situations in a generalized way by providing the designer with skeletons of rules and suggestions about their instantiation, together with indications on relationships with other rules, with the activity flow, and with related information. Pattern based design relies on a pattern catalog containing patterns to be reused and on a formal basis for specializing and instantiating available patterns     

基于词表规则与语句上下文消歧的汉字简繁转换

在简繁汉字转换的处理中,一对多汉字消岐和避免分歧词过度转换是两大难题.构造一对多词表、通用词表、分歧词表,并在词表中加入转换的限制性规则,根据候选词最前或最后的一个字能否与相邻字另外组词,可对该词的有效性进行判断.使用词表中的规则对当前语句上下文进行匹配,综合分析名词、动词、量词和姓氏、词频等属性,从而实现消岐和转换的...     

Reduction rules for time Petri nets

 The goal of net reduction is to increase the effectiveness of Petri-net-based real-time program analysis. Petri-net-based analysis, like all reachability-based methods, suffers from the state explosion problem. Petri net reduction is one key method for combating this problem. In this paper, we extend several rules for the reduction of ordinary Petri nets to work with time Petri nets. We introduce a notion of equivalence among time Petri nets, and prove that our reduction rules yield equivalent nets. This notion of equivalence guarantees that crucial timing and concurrency properties are preserved. Received September 12, 1994/July 4, 1995     

Reduction rules for time Petri nets

The goal of net reduction is to increase the effectiveness of Petri-netbased real-time program analysis. Petri-net-based analysis, like all reachabilitybased methods, suffers from the state explosion problem. Petri net reduction is one key method for combating this problem. In this paper, we extend several rules for the reduction of ordinary Petri nets to work with time Petri nets. We introduce a notion of equivalence among time Petri nets, and prove that our reduction rules yield equivalent nets. This notion of equivalence guarantees that crucial timing and concurrency properties are preserved.     

Reduction rules for reset/inhibitor nets

Reset/inhibitor nets are Petri nets extended with reset arcs and inhibitor arcs. These extensions can be used to model cancellation and blocking. A reset arc allows a transition to remove all tokens from a certain place when the transition fires. An inhibitor arc can stop a transition from being enabled if the place contains one or more tokens. While reset/inhibitor nets increase the expressive power of Petri nets, they also result in increased complexity of analysis techniques. One way of speeding up Petri net analysis is to apply reduction rules. Unfortunately, many of the rules defined for classical Petri nets do not hold in the presence of reset and/or inhibitor arcs. Moreover, new rules can be added. This is the first paper systematically presenting a comprehensive set of reduction rules for reset/inhibitor nets. These rules are liveness and boundedness preserving and are able to dramatically reduce models and their state spaces. It can be observed that most of the modeling languages used in practice have features related to cancellation and blocking. Therefore, this work is highly relevant for all kinds of application areas where analysis is currently intractable.     

Generalized Gaussian quadrature rules over regions with parabolic edges

This paper presents a generalized Gaussian quadrature method for numerical integration over regions with parabolic edges. Any region represented by R ₁={(x, y)| a≤x≤b, f(x)≤y≤g(x)} or R ₂={(x, y)| a≤y≤b, f(y)≤x≤g(y)}, where f(x), g(x), f(y) and g(y) are quadratic functions, is a region bounded by two parabolic arcs or a triangular or a rectangular region with two parabolic edges. Using transformation of variables, a general formula for integration over the above-mentioned regions is provided. A numerical method is also illustrated to show how to apply this formula for other regions with more number of linear and parabolic sides. The method can be used to integrate a wide class of functions including smooth functions and functions with end-point singularities, over any two-dimensional region, bounded by linear and parabolic edges. Finally, the computational efficiency of the derived formulae is demonstrated through several numerical examples.     

Multiagent systems with workflows

Industry and researchers have two different visions for the future of Web services. Industry wants to capitalize on Web service technology to automate business processes via centralized workflow enactment. Researchers are interested in the dynamic composition of Web services. We show how these two visions are points in a continuum and discuss a possible path for bridging the gap between them.     

基于Petri网表示的嵌入式系统模型化简规则(英文)

为了提高基于Petri网表示的嵌入式模型(PRES+)验证的效率,对模型进行了保性变换,给出了一组关于PRES+模型的化简规则,这些化简规则在原模型和简化模型之间保持完全等价关系。对两个系统模型的化简结果进一步说明了这些化简规则的有效性。     

ECA rule-based support for workflows

The use of event–condition–action (ECA) rules has transformed database systems from passive query-based data repositories to active sources of information delivery. In a similar fashion, ECA rules can be used to benefit workflow systems. In this paper, a software framework known as STEP workflow management facility is proposed in order to manage collaborative and distributed workflows and to provide interfaces to object management group-compliant product data management systems. Issues related to implementation using open standards such as CORBA are discussed. A key point underlying the framework is the flexibility it affords to users to re-configure the system according to evolving needs in collaborative product development.     

Scientific workflows with the jABC framework

The jABC is a framework for process modelling and execution according to the XMDD (eXtreme model-driven design) paradigm, which advocates the rigorous use of user-level models in the software development process and software life cycle. We have used the jABC in the domain of scientific workflows for more than a decade now—an occasion to look back and take stock of our experiences in the field. On the one hand, we discuss results from the analysis of a sample of nearly 100 scientific workflow applications that have been implemented with the jABC. On the other hand, we reflect on our experiences and observations regarding the workflow development process with the framework. We then derive and discuss ongoing further developments and future perspectives for the framework, all with an emphasis on simplicity for end users through increased domain specificity. Concretely, we describe how the use of the PROPHETS synthesis plugin can enable a semantics-based simplification of the workflow design process, how with the jABC4 and DyWA frameworks more attention is paid to the ease of data management, and how the Cinco SCCE Meta-Tooling Suite can be used to generate tailored workflow management tools.     

Performance metrics and ontologies for Grid workflows

Many Grid workflow middleware services require knowledge about the performance behavior of Grid applications/services in order to effectively select, compose, and execute workflows in dynamic and complex Grid systems. To provide performance information for building such knowledge, Grid workflow performance tools have to select, measure, and analyze various performance metrics of workflows. However, there is a lack of a comprehensive study of performance metrics which can be used to evaluate the performance of a workflow executed in the Grid. Moreover, given the complexity of both Grid systems and workflows, semantics of essential performance-related concepts and relationships, and associated performance data in Grid workflows should be well described. In this paper, we analyze performance metrics that performance monitoring and analysis tools should provide during the evaluation of the performance of Grid workflows. Performance metrics are associated with multiple levels of abstraction. We introduce an ontology for describing performance data of Grid workflows and illustrate how the ontology can be utilized for monitoring and analyzing the performance of Grid workflows.     

Implicit interaction design for pervasive workflows

The automatic identification capabilities of mobile devices enable the use of implicit interactions to connect the physical world with digital services. For example, users can be provided with information and services just by approaching to them or pointing to them with a mobile device. This kind of interactions can improve business processes by reducing the gap between physical and digital spaces. This work presents Parkour, a design method for workflows that make use of implicit interactions. Parkour allows designers to indicate how implicit interactions can be orchestrated to support a workflow. Furthermore, reconfiguration techniques have been applied to adapt at run-time the degree in which these interactions intrude the user’s mind. Tool support has been developed to automate the validation of the workflow models and support the system reconfiguration. Finally, the proposal has been applied in the development of several workflows.     

Automatically composed workflows for grid environments

Once the realm of high-performance computing for scientific applications, grid computing is rising as a key enabling infrastructure for resource sharing and coordinated problem solving in dynamic multiinstitutional virtual organizations. Grids build over networking technology to provide middleware support such as locating files over a network of computers, scheduling the distributed execution of jobs, and managing resource sharing and access policies.2 The need of scientific communities to interconnect applications, data, expertise, and computing resources is shared by other application areas, such as business, government, medical care, and education.     

Adaptive exception handling for scientific workflows

Scientific workflow systems often operate in highly unreliable, heterogeneous and dynamic environments, and have accordingly incorporated different fault tolerance techniques. We propose an exception‐handling mechanism, based on techniques adopted in programming languages, for modifying at run‐time the structure of a workflow. In contrast to other proposals that achieve the required flexibility by means of the infrastructure, our proposal expresses the exception‐handling mechanism within the workflow language—primarily as two exception‐handling patterns that are exclusively based on the Reference Nets‐within‐Nets formalism (a specific type of Petri nets). When an exception is detected, a workflow in our approach can be re‐written (replaced), based on the particular failure condition that has been detected. This enables workflow users to have better control and understanding of the behaviour of their workflow without having to be aware of the underlying infrastructure. Copyright © 2009 John Wiley & Sons, Ltd.     

Reduction of Unneccessary Dotted Rules in the Earley—Algorithm

With the high developed hardware from the PC‘s today,there arise possibilities to implement programming environments on such kind of computers.To rduces the amount of calculaiton time and required memory space from implemented algorithms.new optimization approaches in the algorithm design are demanded.The purpose of this work is to explore and analyse possibilities to reduce the required memory space through elimination of superfluonus grammar rules created during the process of recognition.     

An environment for designing exceptions in workflows

When designing a workflow schema, the workflow designer must often explicitly deal with exceptional situations, such as abnormal process termination or suspension of task execution. This paper shows how the designer can be supported by tools allowing him to capture exceptional behavior within a workflow schema, by reusing an available set of pre-configured exceptions skeletons. Exceptions are expressed by means of triggers, to be executed on the top of an active database environment. In particular, the paper deals with the handling of typical workflow exceptional situations which are modeled as generic exception skeletons to be included in a new workflow schema by simply specializing or instantiating them. Such skeletons, called patterns, are stored in a catalog; the paper describes the catalog structure and its management tools constituting an integrated environment for pattern-based exception design and reuse.     

基于粗糙集的网关冗余过滤规则约简算法

过量过滤规则存在冗余性影响着网关设备处理性能。在分析过滤规则属性集的基础上,利用粗糙集区分矩阵的性质对过量过滤规则属性集进行约简处理。同时,通过属性权重方法产生过滤规则属性核集实现对过量过滤规则冗余的约简算法。测试证明基于粗糙集的约简算法在网关设备中具有较好的适用性。     

Mining and reasoning on workflows

Today's workflow management systems represent a key technological infrastructure for advanced applications that is attracting a growing body of research, mainly focused in developing tools for workflow management, that allow users both to specify the "static" aspects, like preconditions, precedences among activities, and rules for exception handling, and to control its execution by scheduling the activities on the available resources. This paper deals with an aspect of workflows which has so far not received much attention even though it is crucial for the forthcoming scenarios of large scale applications on the Web: providing facilities for the human system administrator for identifying the choices performed more frequently in the past that had lead to a desired final configuration. In this context, we formalize the problem of discovering the most frequent patterns of executions, i.e., the workflow substructures that have been scheduled more frequently by the system. We attacked the problem by developing two data mining algorithms on the basis of an intuitive and original graph formalization of a workflow schema and its occurrences. The model is used both to prove some intractability results that strongly motivate the use of data mining techniques and to derive interesting structural properties for reducing the search space for frequent patterns. Indeed, the experiments we have carried out show that our algorithms outperform standard data mining algorithms adapted to discover frequent patterns of workflow executions.