BeanBag: An Extensible Framework for Describing, Storing and Querying Components

Abstract

When it became obvious that Object Oriented software applications were falling short of their promise of significant software reuse, the software industry began to look at another solution. Hence the interest in Component Technology. If developers have the means to use off the shelf components, application development time can be reduced and quality will improve. Components are by nature modularised and are more maintainable than other software applications, with easy integration of component versions. When companies want to minimise the expense of developing in-house solutions and the inflexibility of bought-in software, components are introduced, allowing assembly of components into customised solutions. Presently, there are three main component driving forces, the OMG with the CORBA Component Model (CCM), Microsoft with COM Components (COM) and Sun with Enterprise Java Beans (EJB). Enterprise Java Beans is the Java component architecture for developing server side components, as opposed to Java Beans, which is used to develop client side components. Threading, persistence, and security are handled by an EJB Container. All types of components will have to reside in a repository for application developers to find them. In time it will become crucial to be able to query this repository and to view component descriptions. As the situation stands, the EJB Deployment Descriptor does not provide enough semantic information for a developer to understand exactly what a component does. This thesis examines ways of storing components and extracting information transparently from them. It also examines ways of describing component semantics in a way that is extensible. Developers in the future, who realise that certain semantic information is crucial in a component description can create descriptions in a controlled way, and other developers can search this data. The descriptions developed are XML documents, and can be applied to all types of components, even though this thesis focuses on EJBs primarily.