Chapter 3 Configuring Advanced Expressions: Getting Started 57
Classic Expressions in Advanced Expressions
Classic expressions describe basic characteristics of traffic. In some cases, you
may want to use the classic expression syntax in an advanced policy. You can do
so with the advanced expression configuration tool. This can be helpful when
manually migrating older, classic expressions to the advanced expression format.
Note that when you upgrade the NetScaler to version 9.0 or higher, Integrated
Caching policies are automatically upgraded to advanced policy format, and the
expressions in these policies are upgraded to the advanced expression method of
describing a classic expression.
The following is the syntax for all advanced expressions that use the classic
expression syntax:
sys.eval_classic_expr("expression")
The following are examples of classic expressions that you can embed in an
advanced expression using this syntax:
sys.eval_classic_expr("req.ssl.client.cipher.bits > 1000")
sys.eval_classic_expr("url contains abc")
sys.eval_classic_expr("req.ip.sourceip == 10.102.1.61 -netmask
255.255.255.255")
sys.eval_classic_expr("time >= *:30:00GMT")
sys.eval_classic_expr("e1 || e2")
sys.eval_classic_expr("req.http.urllen > 50")
sys.eval_classic_expr("dayofweek == wedGMT")
Configuring Advanced Expressions in a Policy
You can configure an advanced expression of up to 1,499 characters in a policy.
The user interface for advanced expressions depends to some extent on the
feature for which you are configuring the expression, and on whether you are
configuring an expression for a policy or for another use.
When configuring expressions on the command line, you delimit the expression
by using quotation marks (“. . .”or '. . .'). Within an expression, you escape
additional quotation marks by using a back-slash (\). For example, the following
are standard methods for escaping quotation marks in an expression:
"\"abc\""
‘\"abc\"’