- Classic and Default Syntax Policies
- Classic and Default Syntax Expressions
- Converting Classic Expressions to the Newer Default Expression Syntax
- Before You Proceed
One of the most fundamental components of a policy is its rule. A policy rule is a logical expression that enables the policy to analyze traffic. Most of the policy's functionality is derived from its expression.
An expression matches characteristics of traffic or other data with one or more parameters and values. For example, an expression can enable the NetScaler to accomplish the following:
Classic expressions enable you to evaluate basic characteristics of data. They have a structured syntax that performs string matching and other operations.
Following are a few simple examples of classic expressions:
res.http.header Cache-Control contains public
res.http.header Content-Type contains image/
Any feature that uses default syntax policies also uses default syntax expressions. For information about which features use default syntax policies, see the table "NetScaler Feature, Policy Type, and Policy Usage."
Default syntax expressions have a few other uses. In addition to configuring default syntax expressions in policy rules, you configure default syntax expressions in the following situations:
Following are a few simple examples of default syntax expressions:
http.req.url.length <= 500
http.req.cookie.length < 500