基于AOSD 的数字图书馆体系结构1.doc

摘要 面向方面编程是在现有的面向对象编程的基础之上，通过引入一个“方面”（相对于核心类而言）概念而产生的。它在实现上分离和模块化系统的横切关注点。先分离出方面模块，随后再织入到核心类中。面向方面的软件开发方法使横切于整个系统中的关注点的实现更具有模块性，容易实现系统的演化。系统功能构件设计时不需要考虑散杂在对象中的关注点，这样提高了模块的可追踪性、模块的可重用性、系统的可维护性。面向方面建模在软件开发的各个阶段用一致的方法来详述、可视化、构造和文档化方面相关产品，这样在整个软件开发过程可以使用面向方面技术。 数字图书馆是一个十分复杂庞大的系统，有很多非功能需求，且这些非功能需求往往横切整个系统，如日志、性能问题、安全、上下文相关错误处理、Qos监测等等。传统的系统分析设计的方法难以保证开发的效率和质量。这就要引入面向方面的开发方法，以设计更为合理的系统，加速开发进程，，，bstract The Aspect-Oriented paradigm builds on the existing Object Oriented paradigm by introducing the notion of an aspect as opposed to a core class. The AOP separates and modularizes crosscutting concerns at implementation stage. Using this technique, aspects are placed in separate modules that are then woven together with base classes to form an application. The AOP makes the implementation of the crosscutting concerns of the system more modularized ,and more easy to implement the evolvement of the system.It is unnecessary to consider the crosscutting concerns of the system when we design the function component of the system. Consequently it increases the traceability, reusability and adaptability of software .Aspect-Oriented Modeling (AOM) specifies, visualizes, constructs and documents aspect related artifacts in a consistent way at other stage of software development. Thus whole software development process can use aspect-oriented technique. The digital library is a so complex system with many non-functional concerns , such as logging, performance analysis, security, context related error handling, QoS monitoring, etc(always scatter in the whole system) . So the it is very difficulty to guarantee the efficiency and quality of the software with traditionary methods of systems analysis and design . In order to design more logical system, accelerate development process, improve quality of software, we adopt the Aspect-Oriented software development .It also makes it more convenient to integrate resource of these existing digital library, and alleviates the complication of dig