Information flow analysis of scientific workflows

Recently, scientific workflows have emerged as a platform for automating and accelerating data processing and data sharing in scientific communities. Many scientific workflows have been developed for collaborative research projects that involve a number of geographically distributed organizations. Sharing of data and computation across organizations in different administrative domains is essential in such a collaborative environment. Because of the competitive nature of scientific research, it is important to ensure that sensitive information in scientific workflows can be accessed by and propagated to only authorized parties. To address this problem, we present techniques for analyzing how information propagates in scientific workflows. We also present algorithms for incrementally analyzing how information propagates upon every change to an existing scientific workflow.     

科学工作流中基于上下文感知的资源访问控制

网格环境的动态性使得科学工作流执行过程中的资源访问控制成为一个重要的研究课题.因此,提出一种基于上下文感知的资源访问控制机制,对科学工作流的任务上下文及其约束进行了分析和定义.描述了基于上下文感知的资源访问控制算法,并在此基础上设计了基于上下文感知的科学工作流管理系统框架.最后,通过天气预报这个科学工作流实例验证了该算法.     

基于Perti网的工作流访问控制模型研究

提出了一种工作流访问控制模型WACM(Workflow Access Control Model),该模型支持基于角色的授权,通过工作流引擎中的访问控制矩阵进行同步授权,采用Perti网来描述工作流,对工作流参考模型进行了定义和描述,分析了工作流访问控制模型WACM的体系结构,并将该模型应用到电子商务工作流中,建立了基于安全电子商务协议(SET)的访问控制模型。     

Contract-collaboration network method for modeling manufacturing resource control workflows

This paper presents contract-collaboration network (CC-Net) method that is developed to model manufacturing resource control workflows. The CC-Net is an object-oriented class diagram. It depicts the contract-collaboration relationships among the classes in a manufacturing system, with constraints. The CC-Net method uses a primitive modeling block called collaboration module by which the CC-Net is established systematically. This idea is very similar to that of the Lego® block toy. Unlike most workflow modeling methods, the CC-Net method views workflow modeling as a constraint satisfaction process. That is, describing the set of constraint recovery rules corresponding to the constraint violations is regarded as workflow modeling. The obtained set of workflow rules is free from process deadlock and considers all the events of triggering the workflow. We explore the use of the CC-Net method for the workflow modeling of a flexible manufacturing system.     

Scientific workflows

This article commences the special section on scientific workflows. A brief history is given of workflow approaches in general. More detail is given of scientific workflows, including sample applications. Challenges and research issues are then identified. Finally, an overview is given of the articles appearing in this special section.     

Scheduling and flexible control of bandwidth and in-transit services for end-to-end application workflows

End-to-end scientific application workflows that integrate high-end experiments and instruments with large scale simulations and end-user displays are becoming increasingly important. These workflows require complex couplings and data sharing between distributed components involving large data volumes and present varying hard (in-time data delivery) and soft (in-transit processing) quality of service (QoS) requirements. As a result, supporting efficient data transport is critical for such workflows. In this paper, we leverage software-defined networking (SDN) to address issues of data transport service control and resource provisioning to meet varying QoS requirements from multiple coupled workflows sharing the same service medium. Specifically, we present a flexible control and a disciplined resource scheduling approach for data transport services for science networks. Furthermore, we emulate an SDN testbed on top of the FutureGrid virtualized testbed and use it to evaluate our approach for a realistic scientific workflow. Our results show that SDN-based control and resource scheduling based on simple intuitive models can meet the requirements of the targeted workflows with high resource utilization.     

Mining unconnected patterns in workflows

General patterns of execution that have been frequently scheduled by a workflow management system provide the administrator with previously unknown, and potentially useful information, e.g., about the existence of unexpected causalities between subprocesses of a given workflow. This paper investigates the problem of mining unconnected patterns on the basis of some execution traces, i.e., of detecting sets of activities exhibiting no explicit dependency relationships that are frequently executed together. The problem is faced in the paper by proposing and analyzing two algorithms. One algorithm takes into account information about the structure of the control-flow graph only, while the other is a smart refinement where the knowledge of the frequencies of edges and activities in the traces at hand is also accounted for, by means of a sophisticated graphical analysis. Both algorithms have been implemented and integrated into a system prototype, which may profitably support the enactment phase of the workflow. The correctness of the two algorithms is formally proven, and several experiments are reported to evidence the ability of the graphical analysis to significantly improve the performances, by dramatically pruning the search space of candidate patterns.     

Localising temporal constraints in scientific workflows

Temporal constraints are often set when complex e-science processes are modelled as scientific workflow specifications. However, many existing processes such as climate modelling often have only a few coarse-grained temporal constraints globally. This is not sufficient to control overall temporal correctness as we can not find temporal violations locally in time for handling. Local handling affects fewer workflow activities, hence more cost effective than global handling with coarse-grained temporal constraints. Therefore, in this paper, we systematically investigate how to localise a group of fine-grained temporal constraints so that temporal violations can be indentified locally for better handling cost effectiveness. The corresponding algorithms are developed. The quantitative evaluation demonstrates that with local fine-grained temporal constraints, we can improve handling cost effectiveness significantly than only with coarse-grained ones.     

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.