Middleware Challenges Ahead

24 Computer Middleware Challenges Ahead I n the first attempts to define comprehensive software platforms for distributed applications 25 years ago, researchers created basic middleware elements such as remote procedure call, file service, and directory service based on dramatic advances in hardware technology and fast networking and workstation systems. Today, the scope of middleware is broader, and distributed system technology occupies a prominent place in industrial and academic research and development. The term middleware refers to the software layer between the operating system—including the basic communication protocols—and the distributed applications that interact via the network. This software infrastructure facilitates the interaction among distributed software modules. I avoid defining middleware further because its definitions share a common problem: Depending on the application environment, opinions differ as to which components comprise middleware. General middleware systems support the interaction of arbitrary application programs; specific functions such as remote database access, groupware support, and workflow systems require special middleware solutions. A middleware layer seeks primarily to hide the underlying networked environment’s complexity by insulating applications from explicit protocol handling, disjoint memories, data replication, network faults, and parallelism. Further, middleware masks the heterogeneity of computer architectures, operating systems, programming languages, and networking technologies to facilitate application programming and management. Middleware design includes quality of service (QoS) management and information security. Different middleware systems address these issues in different ways. The “Two Decades of Middleware Development” sidebar gives an overview of middleware history. New application requirements challenge the established middleware design principles. As the first phase of middleware evolution draws to a close, we are poised to enter a major middleware design and development phase that requires new insights into distributed system technology.