Microsoft has released a Security Guide for Web Services. The Guide goes through scenarios, patterns, and implementation Guidance for Web Services Enhancements 3.0.
This guide will help you quickly make the most appropriate security decisions in the context of your Web service’s requirements while providing the rationale and education for each option. A scenario-driven approach is provided to demonstrate situations where different security patterns are successful. The guide also combines a series of decision matrices to assist you in applying your own criteria to use the Web service security patterns to meet the requirements of your environment.