A framework supporting component assembly for distributed systems

Software development by assembling pre-fabricated components faces different challenges from software development using programming language-level constructs. This especially true for distributed software systems, in this paper, we briefly discuss these challenges and propose a solution Out suggested solution advocates the separation of three levels of concern: the architectural level the component level, and the distributed object infrastructure level A framework is proposed to facilitate the transitions between the three levels of concern. In this framework a set of Ports and Links is designed to enable separation of core component functionality from inter-component communications. Ports are used to handle incoming/outgoing service requests or events; links are used to deal with communications using communication protocols or middleware. In particular, Links are specialized into various styles, including local style, CORBA IIOP style, Java RMI style, and TCP Socket style, and on the abstraction level, vary from plain links to autonomously intelligent links taking full advantages of services provided by specific middleware such as CORBA services. Due to this separation, the reusability of components is substantially increased and the flexibility of software systems composed from components can be improved A JavaBeans implementation is described, with the PropertyDescriptor and BeanInfo features of the JavaBeans extended to give explicit information about component boundary information, particularly the Ports. Such information can be either used by visual tools to assist component assembly or used by nut-time systems to discover component capabilities. Examples are given to demonstrate the effectiveness of this framework in addressing the challenges faced by component assembly. The applicability of this framework Is also discussed.