英文文献及翻译(计算机专业)(12页).doc

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1、-英文文献及翻译(计算机专业)-第 11 页NET-BASED TASK MANAGEMENT SYSTEMHector Garcia-Molina, Jeffrey D. Ullman, Jennifer WisdomABSTRACTIn net-based collaborative design environment, design resources become more and more varied and complex. Besides common information management systems, design resources can be organi

2、zed in connection with design activities.A set of activities and resources linked by logic relations can form a task. A task has at least one objective and can be broken down into smaller ones. So a design project can be separated into many subtasks forming a hierarchical structure.Task Management S

3、ystem (TMS) is designed to break down these tasks and assign certain resources to its task nodesAs a result of decomposition.al1 design resources and activities could be managed via this system.KEY WORDS：Collaborative Design, Task Management System (TMS), Task Decomposition, Information Management S

4、ystem1 IntroductionAlong with the rapid upgrade of request for advanced design methods, more and more design tool appeared to support new design methods and forms. Design in a web environment with multi-partners being involved requires a more powerful and efficient management system .Design partners

5、 can be located everywhere over the net with their own organizations. They could be mutually independent experts or teams of tens of employees. This article discusses a task management system (TMS) which manages design activities and resources by breaking down design objectives and re-organizing des

6、ign resources in connection with the activities. Comparing with common information management systems (IMS) like product data management system and document management system, TMS can manage the whole design process. It has two tiers which make it much more f1exible in structure.The 1ower tier consi

7、sts of traditional common IMSS and the upper one fulfills logic activity management through controlling a tree-like structure, allocating design resources and making decisions about how to carry out a design project. Its functioning paradigm varies in different projects depending on the projects sca

8、le and purpose. As a result of this structure, TMS can separate its data model from its logic mode1.It could bring about structure optimization and efficiency improvement, especially in a large scale project.2 Task Management in Net-Based Collaborative Design Environment Evolution of the Design Envi

9、ronmentDuring a net-based collaborative design process, designers transform their working environment from a single PC desktop to LAN, and even extend to WAN. Each design partner can be a single expert or a combination of many teams of several subjects, even if they are far away from each other geog

10、raphically. In the net-based collaborative design environment, people from every terminal of the net can exchange their information interactively with each other and send data to authorized roles via their design tools. The Co Design Space is such an environment which provides a set of these tools t

11、o help design partners communicate and obtain design information. Code sign Space aims at improving the efficiency of collaborative work, making enterprises increase its sensitivity to markets and optimize the configuration of resource. Management of Resources and Activities in Net-Based Collaborati

12、ve EnvironmentThe expansion of design environment also caused a new problem of how to organize the resources and design activities in that environment. As the number of design partners increases, resources also increase in direct proportion. But relations between resources increase in square ratio.

13、To organize these resources and their relations needs an integrated management system which can recognize them and provide to designers in case of they are needed.One solution is to use special information management system (IMS).An IMS can provide database, file systems and in/out interfaces to man

14、age a given resource. For example there are several IMS tools in Co Design Space such as Product Data Management System, Document Management System and so on. These systems can provide its special information which design users want.But the structure of design activities is much more complicated tha

15、n these IM S could manage, because even a simple design project may involve different design resources such as documents, drafts and equipments. Not only product data or documents, design activities also need the support of organizations in design processes. This article puts forward a new design sy

16、stem which attempts to integrate different resources into the related design activities. That is task management system (TMS).3 Task Breakdown Model Basis of Task BreakdownWhen people set out to accomplish a project, they usually separate it into a sequence of tasks and finish them one by one. Each

17、design project can be regarded as an aggregate of activities, roles and data. Here we define a task as a set of activities and resources and also having at least one objective. Because large tasks can be separated into small ones, if we separate a project target into several lowerlevel objectives, w

18、e define that the project is broken down into subtasks and each objective maps to a subtask. Obviously if each subtask is accomplished, the project is surely finished. So TMS integrates design activities and resources through planning these tasks.Net-based collaborative design mostly aims at product

19、s development. Project managers (PM) assign subtasks to designers or design teams who may locate in other cities. The designers and teams execute their own tasks under the constraints which are defined by the PM and negotiated with each other via the collaborative design environment. So the designer

20、s and teams are independent collaborative partners and have incompact coupling relationships. They are driven together only by theft design tasks. After the PM have finished decomposing the project, each designer or team leader who has been assigned with a subtask become a 1ow-class PM of his own ta

21、sk. And he can do the same thing as his PM done to him, re-breaking down and re-assigning tasks.So we put forward two rules for Task Breakdown in a net-based environment, incompact coupling and object-driven. Incompact coupling means the less relationship between two tasks. When two subtasks were co

22、upled too tightly, the requirement for communication between their designers will increase a lot. Too much communication wil1 not only waste time and reduce efficiency, but also bring errors. It will become much more difficult to manage project process than usually in this situation. On the other ha

23、nd every task has its own objective. From the view point of PM of a superior task each subtask could be a black box and how to execute these subtasks is unknown. The PM concerns only the results and constraints of these subtasks, and may never concern what will happen inside it. Task Breakdown Metho

24、dAccording to the above basis, a project can be separated into several subtasks. And when this separating continues, it will finally be decomposed into a task tree. Except the root of the tree is a project, all eaves and branches are subtasks. Since a design project can be separated into a task tree

25、, all its resources can be added to it depending on their relationship. For example, a Small-Sized-Satellite.Design (3SD) project can be broken down into two design objectives as Satellite Hardware. Design (SHD) and Satellite-Software-Exploit (SSE). And it also has two teams. Design team A and desig

26、n team B which we regard as design resources. When A is assigned to SSE and B to SHD. We break down the project as shown in Fig 1.It is alike to manage other resources in a project in this way. So when we define a collaborative design projects task model, we should first claim the projects targets.

27、These targets include functional goals, performance goals, and quality goals and so on. Then we could confirm how to execute this project. Next we can go on to break down it. The project can be separated into two or more subtasks since there are at 1east two partners in a collaborative project. Eith

28、er we could separate the project into stepwise tasks, which have time sequence relationships in case of some more complex projects and then break down the stepwise tasks according to their phase-to-phase goals.There is also another trouble in executing a task breakdown. When a task is broken into se

29、vera1 subtasks; it is not merely “a simple sum motion” of other tasks. In most cases their subtasks could have more complex relations.To solve this problem we use constraints. There are time sequence constraint (TSC) and logic constraint (LC). The time sequence constraint defines the time relationsh

30、ips among subtasks. The TSC has four different types, FF, FS, SF and SS. F means finish and S presents start. If we say Tabb is FS and lag four days, it means Tb should start no later than four days after Ta is finished.The logic constraint is much more complicated. It defines logic relationship amo

31、ng multiple tasks.Here is given an example:“Task TA is separated into three subtasks, Ta, T b and Tc. But there are two more rules.Tb and Tc can not be executed until Ta is finished.Tb and Tc can not be executed both，that means if Tb was executed, Tc should not be executed, and vice versa. This depe

32、nds on the result of Ta.”So we say Tb and Tc have a logic constraint. After finishing breaking down the tasks, we can get a task tree as Fig, 2 illustrates.4 TMS Realization TMS StructureAccording to our discussion about task tree model and task breakdown basis, we can develop a Task Management Syst

33、em (TMS) based on Co Design Space using Java language, JSP technology and Microsoft SQL 2000. The task management systems structure is shown in Fig. 3.TMS has four main modules namely Task Breakdown, Role Management, Statistics and Query and Data Integration. The Task Breakdown module helps users to

34、 work out task tree. Role Management module performs authentication and authorization of access control. Statistics and Query module is an extra tool for users to find more information about their task. The last Data Integration Module provides in/out interface for TMS with its peripheral environmen

35、t. Key Points in System Realization Integration with Co Design SpaceCo Design Space is an integrated information management system which stores, shares and processes design data and provides a series of tools to support users. These tools can share all information in the database because they have a

36、 universal Data Mode1. Which is defined in an XML (extensible Markup Language) file, and has a hierarchical structure. Based on this XML structure the TMS h data mode1 definition is organized as following.Notes: Element “Pros” is a task node object, and “Process” is a task set object which contains

37、subtask objects and is belongs to a higher class task object. One task object can have no more than one “Presses” objects. According to this definition, “Prcs” objects are organized in a tree-formation process. The other objects are resources, such as task link object (“Presage”), task notes (“Pros

38、Notes”), and task documents (“Attachments”) .These resources are shared in Co Design database.文章出处：计算机智能研究J,47卷，2007：647-703基于网络的任务管理系统摘 要在网络与设计协同化的环境下，设计资源变得越来越多样化和复杂化。随着信息管理系统的普及，设计资源在各种设计活动的相互联系过程中被迅速组织起来。一整套在逻辑关系中联接的活动和资源可以组成一个任务。一个任务至少有一个对象，并且可被拆分为很多小的子任务。所以设计项目可分为许多子任务，并由它们形成一个严谨的层次结构。任务管理系统（T

39、MS）是被设计来打破这些任务，并指定某些资源去协调其相关工作。这样做的结果就是所有的设计资源和活动都通过这个系统被管理起来。关键词：协同设计，任务管理系统（TMS），任务分解，信息管理系统1 简介随着对先进设计方法的要求的不断提高，支持新的设计方法和形式的设计工具不断涌现。在网络环境下多伙伴参与的设计活动，需要一个更强大和有效率的管理系统。设计伙伴可以在任何地点锁定自己的组织，它们可以让专家或团队数千员工相互独立起来。本文论述了一种通过打破并重组设计资源与活动来管理设计和活动资源的任务管理系统（TMS）。与普通信息管理系统(IMS)比较，例如产品数据管理系统和文件管理系统，任务管理系统能够管理

40、整个设计过程。它的双层结构使之结构更加灵活。底层由传统的普通信息管理系统结构（IMSS）组成，而高层通过控制树形结构来实现逻辑活动的管理，配置资源以及就如何开展设计项目展开设计和决策。其运作模式也会根据项目的规模和目的产生变化。正是由于这种结构，任务管理系统可以把它的数据模型从其逻辑模型中分离出来，这样将会带来结构优化和效益改善，尤其对一个大型项目来说，作用更加明显。2 基于网络的任务管理系统开发环境2.1 设计环境的演进在网络化协同设计过程中，设计师不断变换着自己的工作环境，从个人电脑到局域网等,甚至延伸至广域网。每个设计伙伴，可以是一个单独专家或结合许多项目的几个科研小组，即使在地理位置上

41、相距遥远。在这样网络化协同设计环境中，来自不同网络终端的人们都可以通过协同的设计空间互动的互相交流信息和发送数据。这种环境提供了一整套工具来帮助设计伙伴沟通和获取设计资料。协同空间旨在提高效率的协同工作，使企业增加敏感的市场,优化配置资源。2.2 在互动的网络环境下对资源和活动的管理设计环境的扩展同样造成了一系列新的问题，比如在这种环境下怎么样组织资源和活动。随着设计伙伴数量的不断增加。资源也在成比例的不断增加着。但是不同资源之间的联系也在不断的随着它们的增加而不断提高。如何组织资源间的联系就需要一个综合的管理系统，一个可以组织它们并在各种条件下将其提供给那些需要它的设计师的管理系统。一个解决

42、方法是使用特殊的信息管理系统（IMS）。这种信息管理系统能够提供数据库,文件系统和输入/输出接口来管理已知的资源。举个例子，在工作空间中有各种不同的ISM工具，如产品数据管理系统文件管理系统等。这些系统可以给他们的用户提供他们需要的各种特殊的信息。但是结构的设计活动是一项比IMS所能管理的极限还要复杂的多的活动，因为即使一个简单的设计工作可能也需要处理不同的设计资源比如说文件、汇票和各种设备。不仅仅只有产品的数据或者文件，设计活动同样也需要设计过程所提供的各种组织过程。这篇文章提出了一种新的设计系统，它试图把不同的设计资源放进相关的设计活动中，这个就是任务管理系统（TMS）。3 任务分解模型3

43、.1 任务分解的依据当人们去完成一个项目时，他们通常会先把它分解成一个个的小任务，然后再去一个个的完成它。每个设计的项目都可以看作是一个整体的活动，各种对象和数据。我们定义的这个任务同样也需要一系列的活动和资源，并最少拥有一个活动。因为大的任务可以被分解成小的任务，如果我们将一个项目目标分解成几个低级别的目标，我们定义了将这个项目分解成不同的子任务同时每个目标也都映射到一个子任务。显然，如果每个子任务都完成，这个项目肯定已经被完成掉，所以TMS根据这些任务规划了资源和活动的分配。大多数的网络化协同设计都将他们的目标定在产品的发展上。项目的管理者将这些子任务交给设计师或者设计团队。这些设计师或者

44、团队在项目主管指定的条件下进行他们各自任务的设计。所以这些设计师和设计团队是相互独立的伙伴并且组织松散。当项目主管完成对这些项目的分解时，每个设计师或者设计团队的领队都会被指派一个已经低级别的子任务，并且他们可以做和他们主管同样的事，将这些子任务打破并且重新分配给他的设计师或者团队。因此，在网络环境下我们为任务分解提出了两项规则，松散的组合和有目的的项目。松散的组合指得是两项任务之间的联系很少，当两个子任务被捆绑的很紧的话，它们的设计者之间的通信量将会增加很多。大量的通信只会浪费时间和降低效率，与此同时也会带来错误。管理项目的过程也会变得比平常更加的困难。另一方面，每个任务都有它自己的工作对象

45、。从项目主管的角度来看，每个子任务都是未知的。他们的注意力只会放在结果和这些子任务的内容上，并且可能永远都不会关心这个小黑匣子里面会发生什么。3.2 任务分解模式根据上面的基础,一个项目能被分解为一些子任务，并且当这些分解继续进行时，它最终会组成一个任务树。除非树的结点是一个项目，所有其他的树叶和树枝都是一个个子任务，正是由于一个设计项目可以被分解成一个任务树，所有这些资源都能根据它们之间的关系被添加到适当的位置上，举个例子来说，一个小型的卫星。设计项目可以像卫星一样被分解成2个设计项目。硬件，设计和软件。并且他也可以有2个团队，设计团队A和设计团队B，这些我们都可以把他们看作设计资源，当A被

46、映射到SSE，B映射到SHD时，我们就像图1一样将这个项目分解掉。管理一个项目中的其他资源用的也是这种方法，所以当我们确定了一个设计项目的任务模型时，我们应该首先搞清楚这个项目的目的。这些目标包括系统的目的，业绩的目标，质量的目标等等。然后我们应该确定如何执行这个项目，紧接着我们可以开始将它细化。因为有最少2个的设计伙伴，这些项目可以被分解成一个或者更多的子任务。或者当我们遇到一些更复杂的项目时，可以将这项项目分解成有层次感的任务，并按它们相互间的目标来逐步的实现这些任务。当我们对一个任务进行细化时还将遇到一个难题。当我们将一个任务分解为几个子任务时，我们所要做的并不仅仅是“一个简单运算”，在

47、大多数情况下，这项被细化的子任务具有更加复杂的关联。为了解决这一难题，我们使用了一些约束条件。这项约束条件可分为时分约束（TSC）和逻辑约束（LC）。时分约束定义了子任务间的时间关系。时分约束有四种类型，FF，FS，SF和SS。F的意思是完成，S的意思是开始。当我们说TaTb并且延时四天，它的意思就是Tb应该在Ta结束后四天之内开始。逻辑约束就比较复杂了，它规定了这些多任务之间的逻辑关系。这里举一个例子：“任务TA被分解成3个子任务，Ta，Tb和Tc。但是这里有2个规则需要遵守。Ta结束前，Tb和Tc不能被执行。Tb和Tc不可以同时被执行，这就表示Tb被执行的时候Tc不应该被执行，反之亦然，并且这些都建立在Ta运行结果的基础上。”所以我们说Tb和Tc有逻辑的约束，在完成对这些任务的约束后，我们得到了如图2所示的一个任务树。4 TMS简介4.1 TMS结构通过对任务树模型和任务分解基础的讨论，我们可以想象出一个基于用JAVA语言表达的工作空间的任务管理系统