COM & .NET Component Services

COM+ Just-in-Time Activation

.NET managed components can use COM+ JITA to efficiently handle rich clients (such as .NET Windows Forms clients), as discussed in Chapter 3.

To enable JITA support for your component, use the JustInTimeActivation attribute:

[JustInTimeActivation(true)]
public class MyComponent :ServicedComponent
{..}

When you register this component with COM+, the JITA checkbox in the Activation tab on the Component Services Explorer is selected. If you do not use the JustInTimeActivation attribute, JITA support is disabled when you register your component with COM+ (unlike the COM+ default of enabling JITA). The JustInTimeActivation class default constructor enables JITA support, so the following two statements are equivalent:

[JustInTimeActivation]
[JustInTimeActivation (true)]

Enabling JITA support is just one thing you need to do to use JITA. You still have to let COM+ know when to deactivate your object. You can deactivate the object by setting the done bit in the context object, using the DeactivateOnReturn property of the ContextUtil class. As discussed at length in Chapter 3, a JITA object should retrieve its state at the beginning of every method call and save it at the end. Example 10-3 shows a serviced component using JITA.

Example 10-3. A serviced component using JITA

public interface IMyInterface { void MyMethod(long objectIdentifier); } [JustInTimeActivation(true)] public class MyComponent :ServicedComponent,IMyInterface { public void MyMethod(long objectIdentifier) ...