Citrix Systems 9.2 manual Expression Prefixes for Text, Http Expression Prefixes that Return Text

Chapter 4 Advanced Expressions: Evaluating Text 67

HTTP.REQ.HEADER("Example").AFTER_REGEX(re/more/)

For more information on regular expressions, see “Matching Text With a

Pattern,” on page 164.

Expression Prefixes for Text

The following sections discuss expression prefixes for strings.

Expression Prefixes for Text in HTTP Requests and Responses

An HTTP request or response typically contains text, such as in the form of headers, header values, URLs, and POST body text. You can configure expressions to operate on one or more of these text-based items in an HTTP request or response.

The following table describes the expression prefixes that you can configure to extract text from different parts of an HTTP request or response.

HTTP Expression Prefixes that Return Text

Prefix	Description
HTTP.REQ.BODY(integer)	Returns the body of an HTTP request as a multiline text
	object, up to the character position designated in
	integer.
	There is no maximum value for the body argument, but
	you should use as small a value as is practical. Larger
	values can affect performance.
	Note: Although it is possible to specify this prefix
	without an integer argument, this usage is deprecated.
HTTP.REQ.HOSTNAME	Returns the HTTP host name in the first line of the
	request, if there is one. Otherwise, this prefix returns the
	value in the last occurrence of the HOST header.
	Note that there are two similar prefixes that return host
	names, as follows:
	• http.req.url.hostname only returns the
	host name from the URL
	• http.req.header("Host") only returns the
	value from the Host header. To use this value as a
	host name you must typecast this string, as
	illustrated in the following example: http.req.
	header("host").typecast_http_
	hostname_t
	For more information on typecasting, see
	“Transforming Text and Numbers into Different Data
	Types,” on page 169.