If you work for a medium or large company chances are your environment is heterogeneous. If so, you need to make sure your web-services are platform agnostic. The link below describes a design/development style as well as a few tools used for developing agnostic web-services and messages.
http://www.aniltj.com/blog/2005/10/09/SchemaFirstContractFirstTopDownStyleOfDevelopmentTools.aspx