Why don't these abstract methods need to be implemented?

What am I missing here? In the following webpage, it's expl开发者_StackOverflowained how to write a SOAP extension class:

http://msdn.microsoft.com/en-us/magazine/cc188761.aspx

In the proposed extension class, which begins:

public class XmlStreamSoapExtension : SoapExtension

... only ChainStream and ProcessMessage are implemented. However, if I do something similar and try to build, I get build errors that 3 abstract methods:

GetInitializer(Type serviceType)  
GetInitializer(LogicalMethodInfo methodInfo, SoapExtensionAttribute attribute)
Initialize(object initializer)

... have not been implemented. Have they just been omitted for brevity, or am I missing something here that allows you not to have to implement them?

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if you notice in the example code, the line

  ... // no-op operations omitted for simplicity

says that they have intentionally omitted these methods (for simplicity).

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As stated on the page you link:

I omitted a couple of no-op operations for simplicity.