Osgi Framework Of Distributed Applications

Nowadays, many companies are using J2EE on enterprise level development. Nevertheless system created with J2EE is very inconvenient to modify when it is found difficult to meet the needs through in-depth and long-lasting using. Complex structures, chaotic dependence, the difficulty of modules isolation, and the uncertainty of modification - all of them have absolutely frustrated the developers. Sometimes even a small change in demand will cause the entire project to be rebuilt. In addition, system resources and system response time is always facing the bottleneck as a result of the dramatic increasing amount of users. System expansion is the only choice; still, the process of shifting single machine to multiple machines will become a nightmare of programmers. How can one small change bring about such a huge butterfly effect? Why are the current frameworks and design patterns, which were claimed excellence, so fragile and useless when facing the change?With these questions, I learned about OSGi, just like its slogan, "A dynamic module system for Java", OSGi gives me the answer. First, OSGi is a microkernel framework, including core and services. Any system based on OSGi framework has the functions such as Plug and Play, hot deployment, unPlug and Deletion. Secondly, OSGi is a loosely coupled, plug-ins, high reusability, scalability and dynamicity framework. The most important point is service-oriented feature, which means the communication issue between different products or different manufacturers can be solved.From the perspective of enterprise applications, I studied OSGi core and its operating mechanism in detail, and gave a distributed solution to solve the bottleneck of one single machine. The following are the main parts of this research work: (1) studied the theory of OSGi core, learned at all levels of the core and the relationships between them, and summed up the design concept of OSGi. (2) analyzed the existing open source Equinox and Felix, which is the implementation of OSGi framework. Read the information of their working mechanism by source code analysis. Since there is no testing way of horizontal contrast, I designed a new testing framework, which can be supported by quantitative data, as a scientific proof for the selection of OSGi framework. (3) Proposed a custom framework because of the lack of existing OSGi framework. (4) I designed an OSGi-based distributed application framework (Equinox + Spring-DM + CXF-DOSGi), and then demonstrated it. (5)I verified the feasibility of distributed applications running on the OSGi framework by a retailstore application system design and implementation, and then tested this system to clarify the advantages at last. This research work has great guiding significance and commercial benefit on OSGi-based distributed area.