1 Distributed models
Before looking in detail at some of the technologies it is worth examining some of the implementation and design models that can be used for distributed system development ranging from the familiar, message passing, to the unfamiliar, tuple-based technology. In describing these I have two aims: first, to detail the variety of methods and architectures that are available and the degree of closeness they have to Internet technologies such as TCP/IP, for example message passing is close in concept to the idea of data flowing down a transmission line, while tuple-based development views a distributed system as just a big, persistent store of objects. The second aim is to examine two different categories of architecture and development: those that are associated with the client initiating a data transfer and those associated with the server carrying out the initiation.
The distributed models that I shall look at in this comparatively brief course are: message passing, distributed objects, remote procedure call, event-based technology and tuple-based technology.