03 軟件10-1班 201003031006 李冉 外文翻譯

1、齊 魯 工 業(yè) 大 學(xué)外文資料及中文譯文院系名稱 信息學(xué)院 學(xué)生姓名 李冉 學(xué)生學(xué)號 201003031006 專業(yè)班級 計科（軟件）10-1 指導(dǎo)教師 劉嵩 二一四 年 四 月 六 日外文資料A survey on web services composition_Dustdar_Schreiner_inPressAn orchestration model defines abstractions and languages to define the order in which and the conditions under which web services are invoke

2、d. Orchestration models use process-modelling languages, such as UML activity diagrams, Petri-nets, state-charts, 4 S. Dustdar and W.Schreiner rule-based orchestration, activity hierarchies, and -calculus. Data and data access models define how data is specified and exchanged between components. The

3、 service selection model deals with static and dynamic binding that is how a web service is selected as a component, statically at design-time or dynamically during run-time. Transactions define which transactional semantics can be associated to the composition and how this is done. Finally, we must

4、 also consider a model for exception handling to handle exceptional states during the execution of the composite service without the service being aborted.The Business Process Execution Language for Web Services (BPEL4WS) standard proposed by IBM (Virdell, 2003), Microsoft and BEA (Andrews et al., 2

5、003) is in many cases related to former standards, such as WSFL or XLANG. BPEL descriptions are XML documents, which describe the roles involved in the message exchange, supported port types and orchestration, and correlation information as aspects of a process. BPEL4WS is a service composition mode

6、l (Wohed et al., 2003), which supports both, composition and coordination protocols. It also consists of an activity-based component model, an orchestration model that allows the definition of structured activities, XML schema data types, a service selection model and a mechanism for exception, even

7、t and compensation handling.3 Managing a film crew: a case studyAccording to Dustdar and Treiber (2004) the case study of managing a film crew has been selected, in order to explain the different concepts and frameworks introduced in various papers, with a consistent reference scenario that runs thr

8、ough the whole paper.Basically, a film crew consists of one or more film directors, external experts and crew-members. Each of these teams provides particular services and work together in a loosely coupled way, providing their expertise on demand, while they depend on the services provided by other

9、 film teams.A film director must coordinate the film teams, is responsible for the budget, and must enable communication among different teams. Since different phases in the film production place different requirements on the arrangement of the teams, each phase requires flexible composition and con

10、figuration of the film teams. Directors hire film crews and external experts who provide own services and capabilities necessary for shooting a film. External experts offer their expertise on several topics, such as physics, health, or law to make the film and special effects more realistic. Crew-me

11、mbers may act as stuntmen for example.4 Composition issuesWeb service composition (Benatallah et al., 2001, 2002) is a very complex and challenging task, as will be seen when discussing different composition approaches in greater detail. Before performing web service composition, some basics to enab

12、le service composition have to be performed. Six different issues that have a large impact on service composition have been identified. The following sub-sections do not claim completeness of composition issues. The most important issues may be explained in a few words. The concepts, some standardis

13、ation efforts and related research work as well have been introduced. Sun Microsystems, for example, has proposed standards for coordination (Terai et al., 2003), transaction, and context and has put them together to one comprising standard called WS-CAF (Web Services Composite Application Framework

14、) (Bunting et al, 2003b).Coordination, transaction, context and conversation modelling is discussed. When composing services composite service execution must be considered. Centralised and distributed service execution has been differentiated, and frameworks that fall into these categories have also

15、 been discussed. In addition to the traditional SOA (Service Oriented Architecture) mentioned in the introduction-based infrastructure, there are also alternatives to that. Here, peer-to-peer infrastructure is dealt with and a P2P based framework called Peer-Serv is described, and suggestions to ext

16、end the classical web service model in order to precisely describe web services and facilitate quality driven service discovery (Benatallah et al., 2004a) are presented4.1 CoordinationThe basic web service infrastructure presented in Section 1 satisfies simple interactions and method invocations amo

17、ng interacting entities. When it comes to composing web services and building complex software systems, it is likely that interaction requires coordination of sequences of operations, to ensure correctness and consistency. New protocols and abstractions are needed and this is exactly the case of coo

18、rdination. In order to provide modelling abstractions and simplify web service development, different standardisation efforts, such as WS-Coordination (Cabrera et al., 2002) by IBM or WS-CF by Sun (Bunting et al, 2003a) have been taken.4.2 TransactionTo add guarantee to the interactions, it is of co

19、nsiderable importance to add a transaction (Papazoglou, 2003) protocol to the coordination framework in order to provide short-duration transactions, called atomic transactions, and long running business activities as well. In case of long running activities, it is not always possible to ensureACID

20、(atomicity, consistency, integrity, and durability) properties of web service transactions. Very important to name are the WS-Transaction (Cabrera et al., 2001; Freund and Storey, 2002a, 2002b) standard, proposed by IBM and WS-TXM (Bunting et al, 2003c) suggested by Sun. WS-Transaction builds upon t

21、he WS-Coordination framework mentioned above, since it defines protocols for centralized and peer-to-peer transactions, both of which require the existence of coordination.4.3 ContextThe term context is a very vague one, since many different definitions can be found in literature. In terms of web se

22、rvices, context maybe inferred as information utilised by the web service to adjust execution and output to provide the client with a customised and personalised behaviour (Keidl and Kemper, 2004a; Álvarez et al., 2003). Context is extensible with new types of information at any time, without a

23、ny changes to the underlying infrastructure. Context may contain information such as a consumers name, address, and current location, the type of client device, including hard- and software that the consumer is using, or all kinds of preferences regarding the communication.The WS-Context (Bunting et

24、 al., 2003d) standard, which is part of the WS-CAF standard proposed by Sun, specifies context, context sharing, and context management.中文譯文業(yè)務(wù)流程模型通過定義抽象和語言來定義命令，以及web服務(wù)被調(diào)用的條件。業(yè)務(wù)流程模型使用流程建模語言，如UML活動圖， Petri網(wǎng)，狀態(tài)圖，以4 S. Dustdar 和W. Schreiner規(guī)則為基礎(chǔ)的業(yè)務(wù)流程，活動層次結(jié)構(gòu)和演算。數(shù)據(jù)和數(shù)據(jù)訪問模型定義數(shù)據(jù)是如何規(guī)定的和組件之間的轉(zhuǎn)換。服務(wù)選擇模型處理靜態(tài)和動態(tài)綁

25、定Web服務(wù)器如何被選擇為一個組成部分，在設(shè)計階段是靜態(tài)的，在運行階段是動態(tài)的。事務(wù)定義了事務(wù)語義可以關(guān)聯(lián)到的組成以及如何做到這一點。最后，我們還必須考慮一個用于異常處理的模型在組合服務(wù)的執(zhí)行不被中止服務(wù)情況下處理異常狀態(tài)。業(yè)務(wù)流程執(zhí)行語言是針對Web服務(wù)（BPEL4WS）標(biāo)準(zhǔn)，由IBM（Virdell，2003），微軟和BEA（Andrews等，2003）提出的，許多內(nèi)容是與之前標(biāo)準(zhǔn)相關(guān)的，如WSFL和XLANG。業(yè)務(wù)流程執(zhí)行語言描述的是XML文檔，它描述了消息交換，支持的端口類型和業(yè)務(wù)流程，以及相關(guān)的信息作為各個方面的一個過程中被調(diào)用的規(guī)則。BPEL4WS是一種服務(wù)組合模型（Wohed等，

26、2003），同時支持， 組成和協(xié)調(diào)協(xié)議。它還包括一個基于活動的組成部分 模型，業(yè)務(wù)流程模型，它允許結(jié)構(gòu)化活動的定義，XML 架構(gòu)數(shù)據(jù)類型，服務(wù)選擇模型和機制的異常，事件和 賠償處理。BPEL4WS是一種服務(wù)組合模型（Wohed等，2003），它同時支持組成和協(xié)調(diào)協(xié)議。它還包括一個基于活動的組成部分的模型，一個允許結(jié)構(gòu)化活動的定義的業(yè)務(wù)流程模型，XML架構(gòu)數(shù)據(jù)類型，一個服務(wù)選擇模型和異常處理，事件和 賠償處理機制。3管理攝制組：案例研究根據(jù)Dustdar和Treiber（ 2004）管理一個電影攝制組的案例研究被選中，目的是為了解釋不同的概念和框架結(jié)構(gòu)被引進(jìn)到各種論文，一致的參考情節(jié)貫穿于整個論

27、文?；旧?，一個電影攝制組由一個或多個導(dǎo)演，外部專家和組員組成。每個小組提供特定服務(wù)并以緊密的方式協(xié)同工作，提供他們被需求的專業(yè)知識，而他們依賴于其他電影團(tuán)隊所提供的服務(wù)。電影導(dǎo)演必須協(xié)調(diào)電影隊，負(fù)責(zé)預(yù)算，并且必須使不同的團(tuán)隊之間的溝通。在電影制作的不同過程中，導(dǎo)演會給各個小組分配不同的任務(wù)，每個階段都需要電影團(tuán)隊靈活的分工和配合。導(dǎo)演聘請攝制隊和外部專家為拍攝場景提供必要的服務(wù)和功能。外部專家為一些主題提供他們的專業(yè)知識，如物理，健康或法律使電影和特效更加逼真。劇組成員可作為特技演員的例子。4組成問題Web服務(wù)組件（ Benatallah等人， 2001 ，2002）是一個非常復(fù)雜和挑戰(zhàn)性的

28、任務(wù)，如討論更加詳細(xì)的處理不同的組件的時候可以被看到。在執(zhí)行web服務(wù)組件之前，一些能夠使服務(wù)組件可用的基礎(chǔ)必須被執(zhí)行。六個對服務(wù)組件有很大的影響的不同的問題已得到確認(rèn)。下面的小節(jié)并不主張組件問題的完整性。最重要的問題可以用幾句話來解釋，一些標(biāo)準(zhǔn)化工作及相關(guān)研究工作也被引入到概念里。例如Sun Microsystems，提出了協(xié)調(diào)標(biāo)準(zhǔn)（Terai等， 2003年） ，將事務(wù)和內(nèi)容放在一起構(gòu)成的標(biāo)準(zhǔn)稱為WS -CAF（Web服務(wù)復(fù)合應(yīng)用框架） （Bunting等人， 2003年） 。協(xié)調(diào)，事務(wù)，內(nèi)容和會話模型被討論。當(dāng)組件服務(wù)組合服務(wù)的執(zhí)行必須加以考慮。集中式和分布式服務(wù)執(zhí)行已經(jīng)被分化，屬于這些類別的框架也已經(jīng)進(jìn)行了探討。除了在引入的下層構(gòu)造中提到的“傳統(tǒng)”的SOA （面向服務(wù)的體系結(jié)構(gòu)） ，對此也是可供選擇的。在