Domain specific languages (DSLs) are languages in which the properties of a specific domain can be expressed. In this paper we present an empirical study on the use of a DSL in industry. This DSL encapsulates the details of services that communicate using Windows Communication Foundation (WCF). From definitions of the data contracts between clients and servers, WCF/C# code for service plumbing is generated. We conducted a survey amongst developers that use this DSL while developing applications for customers. The DSL has been used in about 30 projects all around the world. We describe the known success factors of the use of DSLs, such as improved maintainability and ease of re-use, and assert how well this DSL scores on all of them. The analysis of the results of this case study also shows which conditions should be fulfilled in order to increase the chances of success in using a DSL in a real life case.