This post originated from an RSS feed registered with .NET Buzz by Christian Weyer. Original Post: Look Ma what I want - WS-Policy Feed Title: Christian Weyer: Web Services & .NET Feed URL: http://www.asp.net/err404.htm?aspxerrorpath=/cweyer/Rss.aspx Feed Description: Philosophizing about and criticizing the brave new world ... Latest .NET Buzz Posts Latest .NET Buzz Posts by Christian Weyer Latest Posts From Christian Weyer: Web Services & .NET

WS-Policy et. al. This is one of the most appreciated features in the WS-* cornucopia released over the last months ... it is all about defining policies for your Web services.

The current implementation in WSE 2.0 (TP) heavily focuses on WS-SecurityPolicy to describe which security policies are required for communicating with Web services nodes. Aaron Skonnard provides in his article an overview of WS-Policy and other related specifications and defines a general framework that can be used and extended by Web services specifications to describe a broad range of Web services policies. Check it out on MSDN's XML Web Services Developer Center.

WS-Policy defines a general framework that can be used and extended by other Web services specifications to describe a broad range of Web services policies. WS-Policy defines a policy to be a collection of one or more policy assertions (see Figure 1).

A policy assertion represents an individual preference, requirement, capability, or other general characteristic. There are two additional specifications that define standard sets of policy assertions that can be used within a policy expression. The Web Services Policy Assertions Language (WS-PolicyAssertions) specification defines a set of general message assertions and the Web Services Security Policy Language (WS-SecurityPolicy) specification defines a set of common security-related assertions.

WS-Policy provides a flexible and extensible grammar for expressing policies in a machine-readable XML format. The XML representation of a policy is referred to as a policy expression. A policy expression is bound to a policy subject, or in other words, the resource it describes (e.g., a Web service endpoint). The mechanism for associating a policy expression with one or more policy subjects is referred to as a policy attachment.

The WS-Policy specification defines the general model and syntax for policy expressions and policy assertions but stops short of specifying how policies are located or attached to a Web service. The WS-Policy authors expected other specifications to address this issue in a variety of ways. The Web Services Policy Attachment (WS-PolicyAttachment) specification is one such specification that defines how to attach policy expressions to XML elements, WSDL definitions, and UDDI entries.