Programming .NET Components, 2nd Edition

Custom Component Services

The ability to install custom component services in .NET is a major advancement for software engineering and component-oriented programming. Custom component services allow you to fine-tune and optimize the way .NET services your particular application and business logic. Custom component services decouple clients from objects, because they don’t need to coordinate the execution of the custom service; you can focus on implementing the business logic, rather than the service. Examples of custom services include application logging and tracing, performance counters, custom thread management, filtering of method calls, parameter checks, event subscriptions, and so on.

Custom component services are provided in the form of custom context attributes. Ordinary custom attributes (such as the ones discussed in Appendix C) have no use unless you provide the reflection code to look for these attributes, interpret their values, and act upon them. .NET is indifferent to such custom attributes. Unlike generic custom attributes, .NET is very much aware of custom context attributes when they are used on context-bound objects. Context attributes must derive from the class ContextAttribute, defined in the System.Runtime.Remoting.Contexts namespace. When creating a new context-bound object, .NET reflects the object’s metadata and places it in the appropriate context based on the behavior of the attributes. Custom context attributes can affect the context in which the object ...