Question: I am working on a large system, for which I have to use WCF to access a web service. My test code works fine, now I need to integrate my WCF client code into the larger system. I cannot add to the existing 'app.config' file, and would like specify a separate .config file for use by my client code.

How best can I accomplish this?

Thanks!

Answer: 
you can't do this as you like - you can come close, but can't do it totally.

What you could do is add this section to the main app's config file:

```
<system.serviceModel>
   <bindings configSource="bindings.config" />
   <behaviors configSource="behaviors.config" />
   <client configSource="client.config" />
   <services configSource="services.config" />
  .....
</system.serviceModel>

```

So for each section inside `<system.serviceModel>`, you could specify an external config file by using the `configSource=` attribute (and don't let Visual Studio's red squiggly lines confuse it - yes, it **DOES** work!).

You can do this for any configuration **section** - but unfortunately, there's no way to do this for the whole **section group** (`<system.serviceModel>`).

Marc
There is no built-in support for this in WCF unfortunately. You must create your own ChannelFactory subclass and load/parse configuration files yourself. Check out [this post](http://social.msdn.microsoft.com/forums/en-US/wcf/thread/f33e620a-e332-4fd4-ae21-88c750437355/) here on MSDN forums for more implementation details.