Silverlight, WCF, class library
Suppose a frequently used function consumes a Silverlight enabled web service, it is put into a class library naturally to be shared by all projects. There is a nuisance in using this function - the project uses this function is also required to be configured (in its ServiceReferences.ClientConfig) for using the web service. The easiest way to do it, instead of creating and editing ServiceReferences.ClientConfig, is to add a service refererence in EXACTLY THE SAME way as it is added to the class library (i.e. using the same service URL and the same namespace). The best way is to bypass ServiceReferences.ClientConfig completely, and configure end poins and binding in the code of the library.