Programming Visual Basic .NET, Second Edition

Chapter 19. Marshaling and Remoting

The days of integrated programs all running in a single process on a single machine are, if not dead, at least seriously wounded. Today’s programs consist of complex components running in multiple processes, often across the network. The Web has facilitated distributed applications in a way that was unthinkable even a few years ago, and the trend is toward distribution of responsibility.

A second trend is toward centralizing business logic on large servers. Although these trends appear to be contradictory, in fact they are synergistic: business objects are being centralized while the user interface and even some middleware are being distributed.

The net effect is that objects need to be able to talk with one another at a distance. Objects running on a server handling the web user interface need to be able to interact with business objects living on centralized servers at corporate headquarters.

The process of moving an object across a boundary is called remoting . Boundaries exist at various levels of abstraction in your program. The most obvious boundary is between objects running on different machines.

The process of preparing an object to be remoted is called marshaling. On a single machine, objects might need to be marshaled across context, app domain, or process boundaries.

A process is essentially a running application. If an object in your word processor wants to interact with an object in your spreadsheet, they must communicate across ...