Citrix Systems 9.2 Expression to 8191 characters, Must manually validate the request, Return type

190Citrix NetScaler Policy Configuration and Reference Guide

Elements in an HTTP Callout Policy

Parameter		Specifies
Expression-based		Exact HTTP request that the NetScaler is to send as an advanced
request to send to the		expression to 8191 characters.
server	)	If you specify this parameter, you must omit the httpMethod,
(
fullReqExpr		hostExpr, urlStemExpr, headers, and parameters
		arguments.
		The request expression is constrained by the feature where the
		callout is used. For example, an HTTP.RES expression cannot be
		used in a request-time policy bank or in a TCP content switching
		policy bank.
		The NetScaler does not check the validity of this request. You
		must manually validate the request.
Return type		Type of data that the target application returns in the response to
(returnType)		the callout. Valid values:
		• TEXT: Treat the returned value as a text string.
		• NUM: Treat the returned value as a number.
		• BOOL: Treat the returned value as a Boolean value.
		Note: You cannot change the return type after it is set.
Expression to extract		Advanced expression that extracts HTTP.RES objects from the
data from the		response to the HTTP callout. The maximum length is 8191.
response		The operations in this expression must match the return type. For
(resultExpr)
		example, if you configure a return type of text, the result
		expression must be a text-based expression. If the return type is
		num, the result expression (resultExpr) must return a
		numeric value similar to the following:
		"http.res.body(10000).length"
		Note: In some cases, if you set a return type of TEXT and the
		result sent from the server exceeds 16 KB, the result expression
		can return NULL. For example, this can happen when the result is
		a concatenated string that exceeds 16 KB.

Note: If a request or response that you configure in an HTTP callout (-fullReqExpror -resultExpr) contains the expression SYS. HTTP_CALLOUT, the callout can recursively generate additional callouts. You should avoid this. Also, be sure that the HTTP callout configuration is complete. For example, if the callout contains a rule but not a server where the callout is to be sent, it can return a value of “undefined.”

To configure a callout policy using the configuration utility

1.In the left navigation pane, expand AppExpert, and then click HTTP Callouts.