Inversed Delegation For Resource Loading In OSGi

One major principle in software engineering is software modularization to im-prove the reuse of software. Traditional software module reuse provides function code in the form of class libraries, while current software module reuse employs modu-lar framework technology, such as OSGi (Open Source Gateway Initiative) in Java technology, since it can provide more effective features like coexistence of multiple versions and dynamic update. In transporting existing libraries to OSGi framework, most libraries only need the necessary metadata information to form the OSGi module; however, this doesn’t work for some others because they need the execution context of the running application. The relationship between modules is peer-to-peer in OS-Gi framework, which leads to the isolation of the execution context and results in the libraries’not being able to be transported directly. The problem is that the resource loading mechanism is destroyed in the transport process. Therefore, this thesis propos-es an inversed delegation mechanism for resource loading in OSGi, which will find the module that contains the needed resource by analyzing module stack calling sequence under OSGi framework and delegates the resource loading to the found module’s class loader. We verified the effectiveness of this mechanism in the OSGi framework through some experiments, which is summarized as follows:1. Based on the research on resource loading mechanism in library and OSGi frame-work, we analyzed the problem of incorrect resource loading when we ran the transported library in OSGi framework, and proposed an inversed delegation mechanism for resource loading in OSGi.2. Based on the above mechanism, we expanded the OSGi specification and implied the mechanism on the Felix framework. The expansion of the OSGi module layer’s class loading mechanism can help the transported library load the required resources correctly.3. Experiments of possible situations were done to verify the effectiveness of the inversed delegation mechanism for resource loading in OSGi. The transporta-tion experiments of the Hibernate library demonstrated the practical value of the mechanism.