IObserver interface

This core level interface is available within the Base Class Library (BCL) of .NET 4.0 and is available for the older 3.5 as an add-on.

The use is pretty simple and the goal is to provide a standard way of handling the most basic features of any reactive message consumer.

As already seen in the previous chapter, reactive messages flow by a producer and a consumer and subscribe for some messages. The IObserver C# interface is available to construct message receivers that comply with the reactive programming layout by implementing the three main message-oriented events: a message received, an error received, and a task completed message.

The IObserver interface has the following sign and description:

    // Summary: 
    //     Provides a mechanism for receiving push-based notifications. 
    // 
    // Type parameters: 
    //   T: 
    //     The object that provides notification information.This type parameter is 
    //     contravariant. That is, you can use either the...