在线聊天系统中英文对照外文翻译文献

在线聊天系统中英文对照外文翻译文献

中英文对照外文翻译

(文档含英文原文和中文翻译)

Modeling and specification of Web services composition

using

UML-S

Abstract

As Web services composition arouses a growing interest,

most research works address implementation and execution

issues. Therefore, many composition languages (BPEL, XLANG,

WSFL, WSCI, to name a few of them) have been proposed in the

past few years. However, a weakness of these languages is that

they are difficult to use in early stages of development, such as

specification. In this paper, an extensio n to UML 2.0

called ”UML-S: UML for Services” is introduced. UML-S allows

for a Model Driven Engineering (MDE) of Web services and their

interactions.

1. Introduction

Many companies are now using the Web as a platform to

communicate with their partners. The Web and its technologies

allows them to provide Web services to individuals as well as

other businesses.

The main challenges in the Web services paradigm are their

discovery and their composition. In other words, one must be

able to find a suitable Web service for a given task. This process

is called the discovery [18, 19]. The second challenge is the one

that is addressed in this paper. It is known as Web services

composition [4, 10]. In Web services composition, already

defined services are used together to achieve a larger task,

resulting in a new composite and value-added Web service. To

accomplish this purpose, a common approach is to allow the

Web services to interact in a scenario through the use of

messaging mechanisms.

Although a lot of research works deal with Web services

interactions, most of them address language, implementation or

application issues, neglecting early stages of the development

process, such as specification. To address this issue, an extension

to UML 2.0 called ”UML-S: UML for Services” is introduced.

UML-S allows for modeling Web services as well as their

interactions.

The Unified Modeling Language (UML) has been defined by

the Object Management Group (OMG) [2] to express graphically

system development models.

UML-S enables the developers to build composite Web

services by following the principles of the Model-Driven

Architecture (MDA). As a consequence, it is possible to generate

platform-specific code from high-level UML-S models.

This paper is structured as follows. Section 2 provides a

survey of existing approaches to model Web services interactions.

In section 3, the requirements for a good Web services

composition modeling language are put forward. UML-S is then

presented in details in section 4. After that, a case study is

provided in section 5 to observe UML-S in action. Finally, section

6 draws the conclusions and presents future work.

d Work

The Business Process Management Initiative (BPMI) has

developed the Business Process Modeling Notation (BPMN). This

notation is particularly useful to visualize BPEL

[23] is now maintained by the OMG. Unfortunately, one could

reproach to

BPMN its lack of formalism, as explained by Wohed et at. in

[24]. Although BPMN is an interesting solution, we preferred to

extend UML 2.0 to achieve the same purpose. Indeed, UML was

already used as a Process Modeling Language (PML) [9, 13, 16].As

a matter of fact, UML has some very interesting features as a PML:

it is standard, graphical, popular and it contains several diagrams

which allows to model different views of a system.

UML was already considered to describe Web services

composition. In [20], an approach using UML activity diagrams to

do so was presented by Skogan et provide a way to model

the coordination and the sequencing of the interactions between

Web services. They also explain how UML activity diagrams can

be converted into BPEL [1] or in WorkSCo [3].However, in this

approach, methods input/output and data transformation are

modeled in notes (i.e. comments) on the side of the workflow,

which can get quite confusing when the composition flow gets

complex.

Chunming Gao et al. also present in [11] a non-graphical way

to model Web services composition with some mobility and time

constraint. To do so, they introduce Discrete Time Mobile

Ambient calculus (DTMA), an extension to the formal model

called Mobile ambients calculus [5]. Using DTMA, they focus on

modeling BPEL operations. Due to their non-graphical nature,

languages such as DTMA are less user-friendly than graphical like

UML.

Another approach to Web services composition modeling

was proposed by De Castro et al in [6]. In their work, they make

use of the behavior modeling method of MIDAS, a Model-Driven

Architecture (MDA) framework [14]. MIDAS is a model-driven

methodology for the development of Web Information Systems

(WIS) based on the MDA [21], proposed by the OMG [2]. They

introduced Web services composition through UML activity

diagrams in their paper. However, the model is not detailed as

much as necessary to allow code generation as BPEL. Some

features could also be added such as data transformation and

flow control mechanisms.

In [12], Hamadi et al. put forwards Petri nets [17] based

algebra for composing Web services. Petri nets are a well-known

process modeling technique. The pros of using such Petri net

based algebra is that it allows the verification of properties and

the detection of inconsistencies. However, Web services need to

be expressed using algebra constructs before being translated

into a Petri net representation, adding consequently another

necessary stage in the process.

UML-S transformation rules from WSDL 2.0 and to WS-BPEL

2.0 were provided in [8]. UML-S activity diagrams verification and

validation using Petri nets was also detailed in [15].

services composition model requirements

In this part, we state what the requirements for a good Web

services composition modeling language. First of all, it is better

to extends an already existing, well-known standard if it is

adapted instead of coming up with a new model. UML modeling

language is the de facto industry standard. Therefore it is a good

candidate to be extended for Web services composition

modeling. Moreover, UML is widely used and its graphical models

are easily understandable. The modeling language should allow

to represent Web services interfaces as well as the dynamism

induced by their composition. UML class diagram is particularly

adapted to represent interfaces. Additionally, UML activity

diagram is a excellent candidate to model Web services

composition, due to its strength to represent the dynamic. A

good modeling language can also be judged by its simplicity and

its clarity. Graphical languages such as UML are known for being

user-friendly. Finally, it is worth noting that a composite Web

service simply calls other services and makes them interact.

Therefore, there is not a lot of programming involved compared

to usual Web services. As a consequence, a composite Web

service’s code can be generated in its totality from high level

graphical models such as UML’s. 4. UML-S: UML for Services The

main contribution of this paper is ”UML-S: UML for Services”,

an extension to UML 2.0 that allows for modeling Web services

as well as their interactions. In UML-S, both class diagrams and

activity diagrams are used to model and specify respectively Web

services and their interactions. In part 4.1, we present UML-S

extended class diagram. After that, the activity diagram proposal

is detailed in part 4.2.

建模和使用UML-S Web服务组合的规范

摘要

随着Web服务组合引起了越来越多的兴趣，大部分研究工作解决了实现和执行的问题。因此，在过去的几年里许多组成语言（BPEL，XLANG，WSFL，WSCI，仅举几例）已经提出。然而，这些语言的一个弱点在于，它们很难在早期的发展阶段如说明书中使用。在本文中，延伸到UML2.0叫做“UML-S：UML的服务”介绍。 UML-S允许Web服务模型驱动工程（MDE）和它们之间的相互作用。

1.介绍

现在很多公司都使用Web作为平台与合作伙伴进行沟通。互联网和它的技术，使他们能够提供给个人的Web服务以及其他业务。

在Web服务模式的主要挑战是他们的发现和它们的组成。换言之，必须能够找到合适的Web服务对于给定的工作。这一过程被称为发现

[18，19]。第二个挑战是在本文讨论的之一。它被称为Web服务组合[4,10]。在Web服务组合，已定义的服务一起用来实现更大的工作，从而生成了新的复合和增值的Web服务。为了实现这个目的，一个常见的方法是允许Web服务交互场景中通过使用消息传递机制。

尽管很多研究工作处理Web服务交互,其中大部分是解决语言,实现或应用程序问题,忽视了开发过程的早期阶段,如规范。为了解决这个问题,一个扩展UML 2.0称为“UML-S:UML服务”。UML-S允许Web服务以及它们的交互建模。

统一建模语言（UML）已经由对象管理组织（OMG）[2]以图形化表达系统的开发模式定义。

UML-S使开发人员通过下面的模型驱动架构（MDA）的原则来构建组合Web 服务。因此,可以从高级UML-S模型生成特定于平台的代码。

本文的结构如下。第二节提供了一个现有的调查方法模型的Web服务交互。在第三节,要求良好的Web服务组合建模语言。然后在第四节提出了UML-S的细节。之后,提供了一个案例研究在第五节观察UML-S行动。最后,第六节吸引了结论并提出了未来的工作。

2.相关工作

业务流程管理计划（BPMI）开发了业务流程建模符号（BPMN）。这种表示法是特别有用的可视化BPEL流程。BPMN[23]现在由OMG维护。不幸的是，一个Wohed 等的解释可以责备BPMN缺乏形式主义。在[24]。尽管BPMN是一个有趣的解决方案,我们更倾向于扩展UML 2.0来达到相同的目的。事实上,UML已经用作一种过程建模语言(PML)(9、13、16)。作为事实上，UML有一些非常有趣的功能作为PML：它是标准的，图形化的，流行的，它包含几个图表，允许模型系统的不同视图。

UML已经被认为是描述Web服务组成。在文献[20]，由Skogan等提出了使用UML活动图这样做的方法。它们提供了一种方式来协调和Web服务之间的交互的测序建模。他们也说明UML活动图可以被转换成BPEL[1]或WorkSCo[3]。然而,在这种方法中,方法的输入/输出

和数据转换建模在notes(即评论)上的工作流,当组成流程变得复杂时会得到相当混乱的结果。

高春明等人也展示了[11]Web服务组合与一些流动性和时间约束模型非图形的方式。为此，他们引进离散移动环境演算（DTMA），一个扩展名为手机的正式型号ambients演算[5]。他们使用DTMA集中于建模BPEL的操作。由于其非图形特性，语言如DTMA，不太人性化比的图形，如UML。

德卡斯特罗等提出了另一个Web服务组合建模方法6]。在他们的工作,他们利用MIDAS的行为建模方法,模型驱动体系结构(MDA)框架[14]。MIDAS是一个模型驱动的方法发展的网络信息系统”(感知)基于OMG提出的[2]MDA[21]。他们在论文中通过UML活动图引入了Web服务组合。然而，该模型没有详细尽可能必要允许代码生成作为BPEL。也可以添加一些功能如数据转换和流控制机制。

在[12],Hamadi等人提出了基于Petri网[17]的代数组合Web服务。Petri 网是一个著名的流程建模技术。使用这种基于Petri网的代数的优点是它允许验证的属性和不一致性的检测。然而,Web服务需要使用代数表示构造被翻译成佩特里网表示,因此之前添加另一个必要的阶段。

从WSDL 2.0和ws - bpel 2.0[8]中提供了UML-S转换规则。UML-S活动图验证和确认使用Petri网也有详细介绍。

服务组合模型的要求

在本部分中，我们陈述一个好的WEB服务组合建模语言的要求。首先，最好

是延伸一个已存在的、著名的标准，如果它适于取代想出一种新的模式的话。UML 语言是事实上的行业标准。因此，这是一个用于延长WEB服务组合建模的很好的选择。此外，UML应用广泛，它的图形模型是易于理解的。

建模语言应该允许代表Web服务接口以及活力成分诱导。UML类图特别适应代表接口。此外,由于其强度来表示动态,UML活动图是一个优秀的候选人模型的Web服务组成。

一个好的建模语言，也可通过其简单性和其清晰度判断。图形语言，例如UML，以人性化而著称。

最后，值得一提的是，复合Web服务简单地调用其他服务，使他们互动。因此，相比通常的Web服务编程没有涉及很多的编程。其结果是，复合Web服务的代码可以从高标准的图形模型如UML全部产生。

Design and Application of Collaborative Learning System

based on Web to Database Experiment Teaching

Abstract-The course of SQL Server Database Design and

Management is an experiment course that contributes to

cultivate the experiment ability of students, which is a supply to

the database theory teaching. The collaborative learning is an

effective method to progress the quality of teaching. The

collaborative learning system (CLS) based on web is developed

to meet the requirements. The CLS includes the functions of user

management, news management, forum management and

online SQL experiment. The CLS adopted the method of Object-Oriented modeling with UML and is composed of a 3- tier

architecture based on B/S. All the applications' design and coding

are based on the architecture of Microsoft .Net in the system. The

system has been put in use and achieved a satisfied result.

Keywords- collaborative learning; database experiment;

elearning

I. INTRODUCTION

Collaborative Learning as an important learning method has

been applied for a long time. Collaborative learning is a kind of

social activity involving a community of learners and teachers,

where members share and acquire knowledge. As Vygotsky

(1978) pointed out, "in a collaborative scenario, students

interchange their ideas for coordinating when they working for

reaching common goals [2].

It is a strong trend to combine the method with online

learning. As an important education style in China, the

government not only pays more and more attention to online

learning, but also promotes the rapid development of modern

distance education. With the development of information

science, especially computer technology and network technology,

modern distance education by net has turned into a human-centered, man-computer cooperated OCGS, mainly composed of

users (e.g. teacher, students) educational resources, information

passageway (e.g. network), technology support system (e.g.

management subsystem), and so on. The following is the

introduction of their functions and relationships [1]. Distance

learning programmes allow greater flexibility of learning. The

collaborative learning combined with online learning system

based on web will achieved a good result.

Database theory is a major course of Computer Science

department in universities and

professional schools. The experiment teaching is a

supplement to the theory teaching, which contributes to cultivate

the experiment ability of students. A high-level experiment ability

can make the students finding a good job. How to teach database

experiment effectively is a problem to study deeply.

Some teachers and scientists achieved a series of convincing

results in database teaching, such as Prof. Samia Oussena and

Lynne Dunckley in Thames Valley University. They made the

students exercising based on team. They developed a student-centered approach to learning and teaching. The main goal of

the module is to build on database systems concepts that

students were introduced to in the second year studies and cover

more advanced database concepts. The coursework has been

designed on the basis of object relational database systems [3].

These traditional methods almost are based on LAN, which

is restricted to a special area like the laboratory. Another situation

is that the students experiment on a computer individually to

program SQL for an experiment project that the teacher assigned

and the students submit the SQL scripts to their teachers. Then

the teachers read the SQL scripts and run them on their computer

and give a mark to every student. The method is a hard work to

both teachers and students.

It is essential that a database experiment system based on

web should be developed. It will not be limited to time and

distance and is easy to be used by teachers and students. Hence,

we developed a Database Experiment System (CLS) based

Microsoft .Net technology to solve the problems above. The

students may experiment by a browser such as Internet Explorer

and the experiment results can be valued by the CLS

automatically.

In this paper, the requirement analysis of the system is done

firstly. Then, the architecture of CLS is introduced. The design of

the system especial online SQL exercise and discussion on forum

is subsequently expressed. At the end of the paper, a conclusion

is done.