Citrix Systems 9.2 Benutzerhandbuch

You can configure an operation that matches text in a target against a set of 
strings (an array) or a single string within an array. You can also match a target 
against a pattern defined in a regular expression. You can use a regular expression 
to specify wildcard characters in a pattern, such as text, numbers, and spaces.

Finally, you can use typecasting to convert one type of data into another type. For 
example, you can extract a string from an HTTP request POST body and format it 
as an HTTP header for the purpose of inserting the header into an HTTP 
response.

A pattern set compares a target with multiple static strings. A pattern set can be 
efficient if an expression would otherwise have a large number of Boolean OR 
operations. A pattern set reduces the overhead that would be required to process 
the ORs.

For example, you can define a pattern set with the strings “host1” and “host2”, 
“host3” and compare the target against each string. You can also compare the 
target with just one particular string in the set. For example, you can define a 
pattern set with the strings “vserver1”, “vserver2”, vserver3” and compare the 
target against only the string “vserver1”. For this type of comparison, you specify 
a unique index that is assigned to each string in the pattern set.

You can use a pattern set in any expression that evaluates HTTP headers or text. 
For information about expression prefixes for HTTP headers, see 

. For information about expression prefixes for 

text, see 

.