I’ve recently had to start developing a set of WCF services for my company to use.  All good stuff, you might say – and tyou’d be right.  For the most part.

The area in which things get “interesting” is around the requirement for backwards-compatibility with some existing .Net 1.1 applications that consume traditional web services.  These applications are horrendously complex, and the fewer changes to the code base we have to make, the better.  With this in mind, we created the WCF services to mirror the old web services as closely as possible and that’s where the fun began.

The issue that set me on a journey of discovery and hackery was around a method that returned a simple boolean type.

public bool NameIsInList(string name)

{

// implementation

return true;

}

Nothing fancy there.  However, exposing the service using basicHttpBinding had an unfortunate side effect.  The method signature was refactored to :

public void NameIsInList(string name, out bool NameIsInListResult, out bool NameIsInListResultSpecified);

Less than ideal.

No matter what I tried (including contacting Amit) I couldn’t make the down-level compatible web service return a simple boolean result.  Given how much effort we would have to go to to update the calling methods in the legacy systems, I had to find another way forward.

In the end, the solution was extremely simple, if a little hacky.  Create an ASMX web service that handled the calls to the WCF service, and presents the legacy apps with the data they expect.

[WebMethod]
public bool NameIsInList(string name)
{
using (MyWcfService.ServiceClient WcfClient = new MyWcfService.ServiceClient(“WSHttpBinding_MyService”))
{
return WcfClient.NameIsInList(name);
}
}

Not the prettiest solution, but it works.

There are a few extra benefits that I wasn’t expecting from this approach, too.  I’ll post about those tomorrow.