Citrix Systems 9.2 manual Expressions for Extracting Segments of URLs

Chapter 6 Advanced Expressions: Parsing HTTP, TCP, and UDP Data 129

Operations That Evaluate Cache-Control Headers

HTTP Header Operation	Description
Cache-Control header.	Returns the value of the Cache-Control header Max-
MAX_AGE	Age. If this header is absent or invalid, 0 is returned.
	Following is an example:
	http.req.cache_control.max_age.le(3)
Cache-Control header.	Returns the value of the Cache-Control header Max-
MAX_STALE	Stale. If this header is absent or invalid, 0 is returned.
	Following is an example:
	http.req.cache_control.max_stale.le(3)
Cache-Control header.	Returns the value of the Cache-Control header Min-
MIN_FRESH	Fresh. If this header is absent or invalid, 0 is returned.
	Following is an example:
	http.req.cache_control.min_fresh.le(3)
Cache-Control header.S_	Returns the value of the Cache-Control header S-
MAXAGE	Maxage. If this header is absent or invalid, 0 is returned.
	Following is an example:
	http.req.cache_control.s_maxage.eq(2)

Expressions for Extracting Segments of URLs

You can extract URLs and portions of URLs, such as the host name, or a segment of the URL path. For example, the following expression identifies HTTP requests for image files by extracting image file suffixes from the URL:

http.req.url.suffix.eq("jpeg") http.req.url.suffix.eq("gif")

Most expressions for URLs operate on text and are described in “Expression Prefixes for Text in HTTP Requests and Responses,” on page 67. This section discusses the GET operation. The GET operation extracts text when used with the following prefixes:

•HTTP.REQ.URL.PATH

•VPN.BASEURL.PATH

•VPN.CLIENTLESS_BASEURL.PATH