Java Network Programming, Second Edition

Chapter 18. Remote Method Invocation

Historically, networking has been concerned with two fundamental applications. The first application is moving files and data between hosts, which is handled by FTP, SMTP (email), HTTP, NFS, and many other protocols. The second application is allowing one host to run programs on another host. This is the traditional province of Telnet, rlogin, Remote Procedure Call (RPC), and a lot of database middleware; you can also think of CGI as a means to get a server to run a program for a client. Except for the sections on CGI, most of this book has implicitly concerned itself with file and data transfer. Remote Method Invocation (RMI), however, is an example of the second application for networking: running a program on a remote host from a local machine.

RMI is a core Java API and class library that allows Java programs to call certain methods on a remote server. Furthermore, the methods running on the server can invoke methods in objects on the client. Return values and arguments can be passed back and forth in both directions. In essence, parts of a single program run in a Java virtual machine on a local client while other parts of the same program run on a Java virtual machine on a remote server. RMI creates the illusion that this distributed program is running on one system with one memory space holding all the code and data used on either side of the actual physical connection.

What Is Remote Method Invocation?

The Remote Method Invocation API lets ...