Programming .NET Components, 2nd Edition

Leasing and Sponsorship

.NET manages the lifecycle of objects using garbage collection. .NET keeps track of memory allocation and objects accessed by all the clients in the app domain. When an object becomes unreachable by its clients, the garbage collector eventually collects it. If the objects are in the same app domain as the clients, garbage collection functions fine. In fact, even in the case of a client in one app domain accessing an object in a different app domain in the same process, garbage collection still works, because all app domains in the same process share the same managed heap. In the case of remote objects accessed across processes and machines, however, the strategy breaks down because the object may not have any local clients. In this case, if garbage collection were to take place, the garbage collector would not find any references to the object and would deem it garbage, even though there are remote clients (on other machines, or even in separate processes on the same machine) who wish to use the object. The rest of this section addresses this challenge.

In the following discussion, a “remote object” is an object in a different process. The core piece of the .NET remoting architecture designed to address this problem is called leasing and sponsorship . The idea behind leasing is simple: each server object accessed by remote clients is associated with a lease object. The lease object literally gives the server object a lease on life. When a client creates a ...