HTTP: The Definitive Guide

Modularize and Enhance

The theme of HTTP-NG can be captured in three words: “modularize and enhance.” Instead of having connection management, message handling, server processing logic, and protocol methods all intermixed, the HTTP-NG working group proposed modularizing the protocol into three layers, illustrated in Figure 10-1:

• Layer 1, the message transport layer , focuses on delivering opaque messages between endpoints, independent of the function of the messages. The message transport layer supports various substacks (for example, stacks for wireless environments) and focuses on the problems of efficient message delivery and handling. The HTTP-NG project team proposed a protocol called WebMUX for this layer.

• Layer 2, the remote invocation layer , defines request/response functionality where clients can invoke operations on server resources. This layer is independent of message transport and of the precise semantics of the operations. It just provides a standard way of invoking any server operation. This layer attempts to provide an extensible, object-oriented framework more like CORBA, DCOM, and Java RMI than like the static, server-defined methods of HTTP/1.1. The HTTP-NG project team proposed the Binary Wire Protocol for this layer.

• Layer 3, the web application layer , provides most of the content-management logic. All of the HTTP/1.1 methods (GET, POST, PUT, etc.), as well as the HTTP/1.1 header parameters, are defined here. This layer also supports other services built ...