Addressing Dynamism in E-negotiations by Workflow Management Systems

Workflows (Wfs) are a major enabling technology for e-commerce. In our research, a Combined Negotiation (CN) is modeled and enacted using Wf technology. The modeling task captures the sequencing of the individual negotiations as well as the dependencies between them, and the enacting task runs the model. A CN support system (CONSENSUS) is used by the user to perform both tasks. Supporting dynamic modifications to the model during run-time should increase the benefits of our approach. In this paper, we highlight the need for such support by identifying the dynamic aspects that can occur while negotiating the different items of a package (i.e., the CN object). To address these aspects, we experimented using ADEPT, a Wf Management System supporting dynamism. This leads us to discuss the Wf Reference Model of the Wf Management Coalition, and suggest a "dynamic" extension to the current functional areas and architecture. La technologie des Workflows (Wfs) s'est avérée importante pour le commerce électronique. Dans le cadre de notre recherche, une négociation combinée (CN) est modélisée et exécutée utilisant un Wf. La phase de modélisation capture la séquence des différentes négociations ainsi que les dépendances qui existent entre elles. La phase d'exécution quant à elle, permet comme son nom l'indique, d'exécuter le modèle. Un système de support pour les CN (CONSENSUS) est utilisé pour accomplir ces deux tâches. Supporter les modifications dynamiques du modèle lors de l'exécution devrait augmenter les bénéfices de notre approche. Dans cet article, nous mettons l'emphase sur le besoin d'un tel support, ceci en identifiant les aspects dynamiques qui peuvent apparaître lors de la négociation des différents items d'un package (i.e., l'objet de la CN). Nous utilisons ADEPT - un système de gestion de Wf qui supporte le dynamisme - pour étudier ces aspects. Ceci nous mène à discuter le modèle de référence de la Wf Management Coalition, et à proposer une extension "dynamique" à l'architecture actuelle.e-Negotiations, Sourcing, Workflows, Workflow management systems, Dynamism, Négociations électroniques, Approvisionnement, Workflows, Systèmes de gestion de Workflow, Dynamisme

Understanding Legacy Workflows through Runtime Trace Analysis

abstract: When scientific software is written to specify processes, it takes the form of a workflow, and is often written in an ad-hoc manner in a dynamic programming language. There is a proliferation of legacy workflows implemented by non-expert programmers due to the accessibility of dynamic languages. Unfortunately, ad-hoc workflows lack a structured description as provided by specialized management systems, making ad-hoc workflow maintenance and reuse difficult, and motivating the need for analysis methods. The analysis of ad-hoc workflows using compiler techniques does not address dynamic languages - a program has so few constrains that its behavior cannot be predicted. In contrast, workflow provenance tracking has had success using run-time techniques to record data. The aim of this work is to develop a new analysis method for extracting workflow structure at run-time, thus avoiding issues with dynamics. The method captures the dataflow of an ad-hoc workflow through its execution and abstracts it with a process for simplifying repetition. An instrumentation system first processes the workflow to produce an instrumented version, capable of logging events, which is then executed on an input to produce a trace. The trace undergoes dataflow construction to produce a provenance graph. The dataflow is examined for equivalent regions, which are collected into a single unit. The workflow is thus characterized in terms of its treatment of an input. Unlike other methods, a run-time approach characterizes the workflow's actual behavior; including elements which static analysis cannot predict (for example, code dynamically evaluated based on input parameters). This also enables the characterization of dataflow through external tools. The contributions of this work are: a run-time method for recording a provenance graph from an ad-hoc Python workflow, and a method to analyze the structure of a workflow from provenance. Methods are implemented in Python and are demonstrated on real world Python workflows. These contributions enable users to derive graph structure from workflows. Empowered by a graphical view, users can better understand a legacy workflow. This makes the wealth of legacy ad-hoc workflows accessible, enabling workflow reuse instead of investing time and resources into creating a workflow.Dissertation/ThesisMasters Thesis Computer Science 201

A Taxonomy of Workflow Management Systems for Grid Computing

With the advent of Grid and application technologies, scientists and engineers are building more and more complex applications to manage and process large data sets, and execute scientific experiments on distributed resources. Such application scenarios require means for composing and executing complex workflows. Therefore, many efforts have been made towards the development of workflow management systems for Grid computing. In this paper, we propose a taxonomy that characterizes and classifies various approaches for building and executing workflows on Grids. We also survey several representative Grid workflow systems developed by various projects world-wide to demonstrate the comprehensiveness of the taxonomy. The taxonomy not only highlights the design and engineering similarities and differences of state-of-the-art in Grid workflow systems, but also identifies the areas that need further research.Comment: 29 pages, 15 figure

Supporting the Everyday Work of Scientists: Automating Scientific Workflows

This paper describes an action research project that we undertook with National Research Council Canada (NRC) scientists. Based on discussions about their \ud difficulties in using software to collect data and manage processes, we identified three requirements for increasing research productivity: ease of use for end- \ud users; managing scientific workflows; and facilitating software interoperability. Based on these requirements, we developed a software framework, Sweet, to \ud assist in the automation of scientific workflows. \ud \ud Throughout the iterative development process, and through a series of structured interviews, we evaluated how the framework was used in practice, and identified \ud increases in productivity and effectiveness and their causes. While the framework provides resources for writing application wrappers, it was easier to code the applications’ functionality directly into the framework using OSS components. Ease of use for the end-user and flexible and fully parameterized workflow representations were key elements of the framework’s success. \u

A Framework for QoS-aware Execution of Workflows over the Cloud

The Cloud Computing paradigm is providing system architects with a new powerful tool for building scalable applications. Clouds allow allocation of resources on a "pay-as-you-go" model, so that additional resources can be requested during peak loads and released after that. However, this flexibility asks for appropriate dynamic reconfiguration strategies. In this paper we describe SAVER (qoS-Aware workflows oVER the Cloud), a QoS-aware algorithm for executing workflows involving Web Services hosted in a Cloud environment. SAVER allows execution of arbitrary workflows subject to response time constraints. SAVER uses a passive monitor to identify workload fluctuations based on the observed system response time. The information collected by the monitor is used by a planner component to identify the minimum number of instances of each Web Service which should be allocated in order to satisfy the response time constraint. SAVER uses a simple Queueing Network (QN) model to identify the optimal resource allocation. Specifically, the QN model is used to identify bottlenecks, and predict the system performance as Cloud resources are allocated or released. The parameters used to evaluate the model are those collected by the monitor, which means that SAVER does not require any particular knowledge of the Web Services and workflows being executed. Our approach has been validated through numerical simulations, whose results are reported in this paper