Follow your heart (102)-----Indian's design document
I think they copied this part for every project , but anyway , i can learn something from it. 说实话,有些我还没看明白.除了打省略号的是从我这边的文档copy过去,略加变了几句外.

1 Design Overview
1.1 Architectural Goals and Constraints

The overall architecture goals of the system is to provide a highly available and scalable ********Application for users, to ********
.
The Travel****Application can be used by travellers -
?*********************

A key Architectural goal is to leverage industry best practices for designing and developing a scalable, enterprise-wide J2EE application. To meet this goal, the design of the ****Application will be based on core J2EE patterns as well as the industry standard development guidelines for building the ****Application.

总的看,好像他们是用j2ee做项目


1.2 Guiding Principles

Guiding principles provide a foundation upon which to develop the target architecture for the screening tool, in part by setting the standards and measures that the tool must satisfy. These in turn drive design principles that can be used to validate the design and
ensure that it is aligned with **** overall Architecture, Design Principles and Standards.

1.2.1 Scalable

Scalability is the ability of the platform to scale both up and down to support varying numbers of users or transaction volumes. The application should be able to scale horizontally (by adding more servers) or vertically (by increasing hardware capacity or software efficiency).
1.2.2 Flexible

Flexibility is the ability of the application to adapt and evolve to accommodate new requirements without affecting the existing operations. This relies on a modular architecture, which isolates the complexity of integration, presentation, and business logic from each other in order to allow for the easy integration of new technologies and processes within the application.
1.2.3 Standards-Based

Portal services will comply with established industry standards. The standards-compliance will not only apply to application development but also to design, platform/infrastructure and other parts of the Travel Management application. Examples of standards include HTML, XML, J2EE, and JSP.
1.3 Design Patterns

Design patterns are elements of reusable object oriented software. A design pattern catalog is a repository of design patterns. Use of such patterns makes the design of an application transparent. These patterns have been used successfully by developers in their respective fields, and therefore, the pros and cons of the pattern (as well as implementation issues) are known beforehand. All design patterns are reusable and can be adapted to particular contexts.
Some of the design patterns which will be used in the design and development of the Travel Management Application are -
? Front Controller
? Session Fa?ade
? Business Delegate
? Data Access Object
? Value Object

1.3.1 Front Controller

The Front Controller pattern helps to implement a centralized entry point that controls and manages user (screen) request handling. The controller manages the handling of the request, including invoking security services such as authentication and authorization, delegating business processing, managing the choice of an appropriate view, handling errors, and managing the selection of content creation strategies.
1.3.2 Session Facade

The Session Fa?ade pattern (using a session bean as a fa?ade) helps to encapsulate the complexity of interactions between the business objects participating in a workflow. It manages the business objects, and provides a uniform coarse-grained service access layer to clients, that expose only the required interfaces.
1.3.3 Business Delegate

The Business Delegate pattern helps to