05 Fakultät Informatik, Elektrotechnik und Informationstechnik

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Publication Type: search.filters.UBSTyp.ArbeitspapierStart date: 2007Subject: search.filters.subject.004

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Now showing 1 - 10 of 25
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    Abstract syntax of WS-BPEL 2.0
    (2008) Kopp, Oliver; Mietzner, Ralph; Leymann, Frank
    WS-BPEL 2.0 is the current version of the "Business Process Execution Language for Web Services". Until now, no formal definition of its syntax exists. We present a complete syntax of WS-BPEL 2.0 of both abstract and executable processes.
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    Fragments of first-order logic over infinite words
    (2009) Diekert, Volker; Kufleitner, Manfred
    We give topological and algebraic characterizations as well as language theoretic descriptions of the following subclasses of first-order logic for omega-languages: Sigma2, FO2, the intersection of FO2 and Sigma2, and Delta2 (and by duality Pi2 and the intersection of FO2 and Pi2). These descriptions extend the respective results for finite words. In particular, we relate the above fragments to language classes of certain (unambiguous) polynomials. An immediate consequence is the decidability of the membership problem of these classes, but this was shown before by Wilke and Bojanczyk and is therefore not our main focus. The paper is about the interplay of algebraic, topological, and language theoretic properties.
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    Coordination protocols for split BPEL loops and scopes
    (2007) Khalaf, Rania; Leymann, Frank
    The document presents an approach to enable loops and fault handling, compensating scopes to be split among a set of BPEL processes running on different BPEL engines. A mechanism to split a scope or loop into multiple fragments is presented, then a protocol is defined that can be used to coordinate fragments of a loop or a scope so that those fragments run as if they had been in a single process. The requirements for running split scopes and loops are explained. For compensation, this paper focuses on explicit compensation and makes the assumption that compensation handing does not fail. Two protocols are defined such that they may be plugged into the WS-Coordination framework. The messages between the participant fragments and the coordinator are defined. The information about the participating processes that the coordinator needs to have is specified. An algorithm is provided to locate a fault handler in the hierarchy of scopes that can handle a particular BPEL fault. Additionally, the behavior of both participants and the coordinator are specified.
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    Propagation of states from BPEL process instances to Chevron models
    (2011) Schumm, David; Karastoyanova, Dimka; Leymann, Frank; Lie, Sumadi
    This report describes key aspects of a code library that we developed for the purpose of state propagation for business process monitoring on different levels of abstraction. The library supports the propagation of execution states of process instances based on the Business Process Execution Language (BPEL) to process models specified in the "Chevron" language. The Chevron language is an abstract, non-executable process language that we especially designed for abstract process instance monitoring purposes. The look and feel of this graphical language is similar to value chains. The basic concept of the Chevron language is based on Chevron-shaped charts which can be modeled in Microsoft PowerPoint to describe a process on a high level of abstraction. We aim at enabling the use of high-level process in order to monitor the instance status of a much more detailed, lower-level model. We describe the overall procedure of performing state projections along a concrete scenario. We describe a format for state propagation rules which define how the status of activities of a BPEL process instance should be projected to the elements of a Chevron model. We present a format to serialize process models in the Chevron language. We present a graphical template based on Scalable Vector Graphics (SVG) which we employ to render a stateful Chevron model graphically. The Chevron language is just one language to be used for abstract representation of process instances. However, the approach for state propagation is generic and can be applied for other languages, too.
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    First-order fragments with successor over infinite words
    (2010) Kallas, Jakub; Kufleitner, Manfred; Lauser, Alexander
    We consider fragments of first-order logic and as models we allow finite andinfinite words simultaneously. The only binary relations apart from equalityare order comparison < and the successor predicate +1. We givecharacterizations of the fragments Sigma2 = Sigma2[<,+1] and FO2 = FO2[<,+1] interms of algebraic and topological properties. To this end we introduce thefactor topology over infinite words. It turns out that a language L is in theintersection of FO2 and Sigma2 if and only if L is the interior of an FO2language. Symmetrically, a language is in the intersection of FO2 and Pi2 ifand only if it is the topological closure of an FO2 language. The fragmentDelta2, which by definition is the intersection Sigma2 and Pi2 contains exactlythe clopen languages in FO2. In particular, over infinite words Delta2 is astrict subclass of FO2. Our characterizations yield decidability of themembership problem for all these fragments over finite and infinite words; andas a corollary we also obtain decidability for infinite words. Moreover, wegive a new decidable algebraic characterization of dot-depth 3/2 over finitewords. Decidability of dot-depth 3/2 over finite words was first shown by Glaßer andSchmitz in STACS 2000, and decidability of the membership problem for FO2 overinfinite words was shown 1998 by Wilke in his habilitation thesis whereasdecidability of Sigma2 over infinite words was not known before.
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    WS-BPEL extension for semantic web services (BPEL4SWS), version 1.0
    (2008) Karastoyanova, Dimka; Van Lessen, Tammo; Leymann, Frank; Nitzsche, Joerg; Wutke, Daniel
    The Web Services Business Process Execution Language, version 2.0 (WS-BPEL 2.0 or BPEL for brevity) introduces a model for business processes based on Web services. A BPEL process orchestrates interactions among different Web services. The language encompasses features needed to describe complex control flows, including error handling and compensation behavior. BPEL for Semantic Web Services (BPEL4SWS) uses Semantic Web Service Frameworks to define a communication channel between two partner services instead of using the partner link which is based on WSDL 1.1. It enables describing activity implementations in a much more flexible manner based on ontological descriptions of service requesters and providers.
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    Rankers over infinite words
    (2010) Dartois, Luc; Kufleitner, Manfred; Lauser, Alexander
    We consider the fragments FO2, the intersection of Sigma2 and FO2, the intersection of Pi2 and FO2, and Delta2 of first-order logic FO[<] over finite and infinite words. For all four fragments, we give characterizations in terms of rankers. In particular, we generalize the notion of a ranker to infinite words in two possible ways. Both extensions are natural in the sense that over finite words, they coincide with classical rankers and over infinite words, they both have the full expressive power of FO2. Moreover, the first extension of rankers admits a characterization of the intersection of Sigma2 and FO2 while the other leads to a characterization of the intersection of Pi2 and FO2. Both versions of rankers yield characterizations of the fragment Delta2. As a byproduct, we also obtain characterizations based on unambiguous temporal logic and unambiguous interval temporal logic.
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    Methods for coreference visualization and annotation
    (2010) Burkovski, Andre; Heidemann, Gunther; Kobdani, Hamidreza; Schütze, Hinrich
    In this report we present methods for visualization of coreferences. We use Self Organizing Maps, graph-based models, and text-based techniques to visualize coreference information from a pair-wise model and offer an interactive presentation of the feature space. We introduce our software system and several visualizations of the Self Organizing Map. The visualizations enable the user to explore the feature space, provide insights for feature engineering and allow a fast annotation of data with coreference information.
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    A prototype for view-based monitoring of BPEL processes
    (2011) Schumm, David; Latuske, Gregor; Leymann, Frank
    This report describes the initial version of a tool for business process monitoring based on process viewing techniques. The tool, Business Process Illustrator (BPI), has been developed in the course of a Diploma Thesis which has been conducted at the Institute of Architecture of Application Systems. BPI is a Web-based tool for monitoring the execution of business processes. It displays the current state of a process instance in form of a process graph which is refreshed regularly. The initial version of the prototype supports regular process monitoring of processes based on the Business Process Execution Language (BPEL), plus process view transformations to reduce complexity and to ease analysis of process instances.
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    An event model for WS-BPEL 2.0
    (2011) Kopp, Oliver; Henke, Sebastian; Karastoyanova, Dimka; Khalaf, Rania; Leymann, Frank; Sonntag, Mirko; Steinmetz, Thomas; Unger, Tobias; Wetzstein, Branimir
    This report presents an engine-independent WS-BPEL 2.0 event model. It supports both passive monitoring and active control of process execution by external applications. Some of the assumptions in the presented event model are inspired by a particular implementation, e.g. fault handling and compensation; however they are kept as general as possible, so that they can be mapped on other engine-specific approaches to tackle faults and support compensation. In addition, the report draws on the experience of some of the authors in business process management and software development. The overall BPEL event model consists of a set of event models for the different types of BPEL entities that change their states: processes, process instances, general activities, scope activities, invoke activities, loops, links, variables, partner links, and correlation sets. The event model is used by the authors of the report in several projects, all utilizing process life cycle events in different scenarios.