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[Translate veryday]科学工作流综述与研究方法(二)

(2009-03-12 00:01:24)
标签:

e-science

科学工作流

编制

编排

web服务

it

分类: 天天翻译

2 Business workow technology

2.业务工作流技术

    As workow technology was rst adopted by the business community, this has led to a space crowded with competing specications, from opposing companies, some of which have risen to the top, superseding others. Before discussing the standards it is important to note that there are two main architectural approaches to implementing workow; service orchestration and service choreography.

    随着工作流技术首次被商业界采用,由此带来了各种规范相互竞争的空间,在这些相互对立的规范中,一些已经上升到顶端,取代了其他的规范。在讨论标准之前必须着重指出,目前有两个主要的架构方法可以实施工作流:服务编制和服务编排。

    Service orchestration refers to an executable business process that may interact with both internal and external services. Orchestration describes how services can interact at the message level, with an explicit definition of the control and data flow. Orchestrations can span multiple applications and/or organisations and result in long-lived, transactional processes. A central process always acts as a controller to the involved services and the services themselves have no knowledge of their involvement in a higher level application.

    服务编制涉及一个可执行的业务流程,它可以与内部和外部服务相结合。编制描述了服务之间是如何通过控制和数据流的精确定义而在信息级别相互作用的。编制可以跨越多重应用程序和/或组织,从而导致处理过程的延长。总有一个核心进程充当相关服务的控制器,而服务本身并不知道他们参与了更高层次的应用。

    The Business Process Execution Language (BPEL) [2] is an executable business process modelling language and currently the current de-facto standard way of orchestrating Web services. It has broad industrial support from companies such as IBM, Microsoft and Oracle. Industrial support brings concrete implementations, tools and training. Recent eorts from the Open Middleware Infrastructure Institute UK (OMII-UK) have resulted in an open-source graphical editor, called BPEL Designer [3].

    业务流程执行语言( BPEL )[2]是一个可执行的业务流程建模语言和目前现有的编制Web服务的实际上的标准方式。它具有广泛的工业支援机构,诸如IBM 、微软和甲骨文。工业支援带来了具体的实施、工具和培训。最近英国开放中间件基础架构研究所( OMII-英)通过努力,已研发出了一个开源图形编辑器,即所谓的BPEL设计器[3] 。

    Other languages have been developed but have not been as widely adopted

by the community. Yet Another Workow Language (YAWL) [4] is based on the rigourous analysis of workow patterns, a particular type of design pattern.YAWL aims to support all (or most) of the workow patterns and has a formal underpinning based on Petri-nets. The language is supported by an an Open Source implementation [5] and has some industrial support. XML Process Denition Language (XPDL) is a format standardised by the Workow Management Coalition (WfMC) to interchange Business Process denitions between dierent workow products like modelling tools and workow engines. WfMOpen [6] is an open-source J2EE based implementation of a workow engine as proposed by the Workow Management Coalition (WfMC) and the Object Management Group (OMG), WfMOpen uses XPDL as input.

    也有一些其他的语言开发出来了,但尚未获得社会的广泛采用。然而,有另一种基于严谨分析的工作流模式的工作流语言(YAWL)[4],这是一种独特类型的设计模式。YAWL旨在支持所有(或大多数)的工作流模式,并已正式获得基于Petri网的支撑。这种语言通过开放源码的执行来实现[5],并有一定的工业支持。XML过程定义语言(XPDL)是一种由工作流管理联盟(WfMC)格式化的标准,以实现不同业务流程定义的交换,比如建模工具和工作流引擎工具等不同工作流产品之间的定义。WfMOpen [6]是一种基于开源的J2EE的工作流引擎执行,它由工作流管理联盟(WfMC)和对象管理集团(OMG)提议使用,WfMOpen使用XPDL作为输入。

    Service choreography on the other hand is more collaborative in nature. A choreography model describes a collaboration between a collection of services in order to achieve a common goal. Choreography describes interactions from a global perspective, meaning that all participating services are treated equally,in a peer-to-peer fashion. Each party involved in the process describes the part they play in the interaction. Choreography focuses on message exchange, all involved services are aware of their partners and when to invoke operations. Orchestration diers from choreography in that it describes a process ow between services from the perspective of one participant (centralised control), choreography on the other hand tracks the sequence of messages involving multiple parties (decentralised control, no central server), where no one party truly owns the conversation.

    另一方面,服务编排具有更多的协作性质。编排模型描述了一个服务集合之间的协作,以实现一个共同的目标。编排从全局的角度描述相互作用,也就是说,以一种点对点的方式平等地处理所有正在参与的服务。参与这一进程的每部分描述其在相互作用中各自的功能。编排的重点是信息交流,所有参与的服务都知道到哪些是自己的同组以及何时启动调用操作。编制不同于编排的地方是,它从一名参与者(中央控制)的角度描述服务间的流程,相反编排则跟踪涉及多重参与者(分散控制,没有中央服务器)的信息序列,而没有任何一方拥有真正的对话。

    The Web Services Choreography Description Language (WS-CDL) [7] is an XML-based language that can be used to describe the common and collaborative observable behavior of multiple services that need to interact in order to achieve a shared goal. WS-CDL describes this behavior from a global or neutral perspective rather than from the perspective of any one party. WS-CDL is designed to sit on top of the Web services interface language, WSDL. WSDL focuses on capturing message types, while WS-CDL is about capturing behaviour. A user models a choreography from a global perspective, then each service will have to be programmed by a developer in such a way that they talk to one another, and in doing so, enforce the constraints of the choreography. WS-CDL supersedes the Web Service Choreography Interface (WSCI), although the language is dened by a W3C specication, at the time of writing no implementations exist and interest in the specication has dwindled.

    Web服务编排描述语言(WS-CDL)[7]是一种基于XML的语言,可以用来描述共同协作的可观察的多重服务的行为,这些服务需要相互作用以实现一个共同的目标。

WS-CDL从一个全局或中间的立场描述这种行为,而不是从任何单独的一方。WS-CDL旨在凌驾于Web服务界面语言WSDL之上。WSDL注重采集信息的类型,而WS-CDL专注于采集行为。用户从全局的立场为编排建模,然后开发人员必须以使其相互对话的方式为每一项服务编程,并在这样做时,以此强制执行限定的编排。WS-CDL取代了Web服务编排接口(WSCI),虽然它由W3C规范定义,但是在编写时并没有执行,规范的重要性也已减小。

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