Component-based Operating System APIs: A Versioning and Distributed Resource Solution

Component software techniques have been developed to facilitate software reuse. State and functionality are encapsulated inside components with the goal of limiting program errors due to implicit interactions between components. Late binding of components allows implementations to be chosen at run-time, thereby increasing opportunities for reuse. Current component infrastructures also provide version management capabilities to control the evolutionary development of components. In addition to the general goal of reuse, component software has also focused on enabling distributed computing. Current component infrastructures have strong support for distributed applications. By leveraging these strengths of component software, a component-based operating system (OS) application programmer interface (API) can remedy two weaknesses of current monolithic, procedural APIs. Current APIs are typically very rigid; they can not be modified without jeopardizing legacy applications. This rigidity results in bloat in both API complexity and support code. Also current APIs focus primarily on the single host machine. They lack the ability to name and manipulate OS resources on remote machines. An API constructed entirely of components can leverage version management and distributed computing facilities. Version management can be used to identify legacy APIs, which can then be dynamically loaded. OS resources modeled as components can be instantiated on remote machines and then manipulated with the natural access semantics. We have developed the COP system as prototype component-based API for Windows NT. The system provides an API with version management capabilities and with a method for naming and manipulating remote OS resources. The advantages are gained with a minimum of overhead and without sacrificing legacy compatibility.