| The methodology of programming is one of the focuses in the field of software engineering. The traditional programming methods such as OOP(object-oriented programming) could not satisfy complex and distributed applications, so component software and component models come up. COM(component object model) and other technologies derived from COM, such as DOOM, ActiveX, COM+, are developed by Microsoft to establish component-based programming architecture. Reusable, maintainable and robust applications could be constructed based on COM.This paper researches the mechanism of COM, in which the supporting environment of COM technology is analyzed, the inner running mechanism is studied, the characteristics of COM component and their implementations on Windows platform are set forth, and the running environment is simulated, which is prepared for COM transplantation from Windows platform to others. Subjects of COM in-process server have been simulated: 1 . the mechanism of memory management; 2. the integration of component; 3. some of the kernel API functions in COM library.The paper researches the communication mechanism of COM, in which the technologies of marshaling and connection point support the COM group communication is analyzed, a new communication model?group communication model based on COM is put forward, load -balance, fault-tolerance and security of the model are studied, the main objects in the model are implemented and the interactions among their interfaces are normalized. The author presents a kind of new centralized load-balance algorithm based on static and dynamic task scheduling strategies. This algorithm can work better in realizing gathering load information automatically by applying call-back mechanism of connection object, assigning tasks conveniently by configuring DCOM server, and tolerating fault during several emergencies by introducing the concept of optimum-server and optimum-spare-server into task reallocation.A summary of the works is given and the future work of the communication model based on COM is pointed out in the end of this paper. |
