Layer 2: Remote Invocation

10.6 Layer 2: Remote Invocation

The middle layer of the HTTP-NG architecture supports remote method invocation. This layer provides a generic request/response framework where clients invoke operations on server resources. This layer does not concern itself with the implementation and semantics of the particular operations (caching, security, method logic, etc.); it is concerned only with the interface to allow clients to remotely invoke server operations.

Many remote method invocation standards already are available (CORBA, DCOM, and Java RMI, to name a few), and this layer is not intended to support every nifty feature of these systems. However, there is an explicit goal to extend the richness of HTTP RMI support from that provided by HTTP/1.1. In particular, there is a goal to provide more general remote procedure call support, in an extensible, object-oriented manner.

The HTTP-NG team proposed the Binary Wire Protocol for this layer. This protocol supports a high-performance, extensible technology for invoking well-described operations on a server and carrying back the results. We discuss the Binary Wire Protocol in a bit more detail later in this chapter.