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Citrix NetScaler 12.1 Advanced Policy Expression Reference

The list of expressions that can be used to define advanced policies on the NetScaler appliance.

You can use this reference information in two ways:

Constructing an expression with each click. Use this approach when you want to know the prefix in which you can use the expression, while getting details of the expression.

Start by clicking one of the prefixes mentioned in the "starting prefixes" table. You will get a list of expressions that can be used with the selected prefix. From this list, click the return type of the required expression and continue this process till you have constructed the entire expression.

Examples

Finding an expression of a specific type. Use this approach when you want to find an expression of a particular type.

For example, if you want to see a list of all the expressions that can be used on text, click the appropriate link in the navigation tree on the left hand side.

Examples for constructing an expression

Some examples on using this reference documentation to construct a complete policy expression.

1. Append the string "ABCDE" to the body of an HTTP request.

Navigation in this doc Expression formed
1. Click HTTP. HTTP
2. Click REQ. HTTP.REQ
3. Click BODY. HTTP.REQ.BODY
4. Click APPEND (text_t str) and specify the string as ABCDE. HTTP.REQ.BODY.APPEND("ABCDE")

2. Check whether cache control headers are present in an HTTP response.

Navigation in this doc Expression formed
1. Click HTTP. HTTP
2. Click RES. HTTP.RES
3. Click CACHE_CONTROL. HTTP.RES.CACHE_CONTROL
4. Click IS_INVALID. HTTP.RES.CACHE_CONTROL.IS_INVALID

3. To retrieve the protocol of the current packet.

Navigation in this doc Expression formed
1. Click CLIENT. CLIENT
2. Click IP. CLIENT.IP
3. Click PROTOCOL. CLIENT.IP.PROTOCOL

The following table lists the prefixes using which you must start creating an expression:

Starting Prefixes Description
AAA Denotes the AAA context of the current transaction.
ANALYTICS Provides access to analytics information and operations.
CLIENT Designates an expression that refers to the client. This is the starting point for access into parameters such as Ether and SSL.
DIAMETER Models the DIAMETER message.
DNS Models the DNS message.
HTTP Models the HTTP message.
URL URL provides operations for parsing and operating on the URL. The supported format is [<protocol>://<hostname>]<path>[?<query>]. The Text object backing a HTTP URL object has the Text Mode set to URLENCODED by default.
ICA Models the ICA protocol.
MSSQL Models the MSSQL protocol.
MYSQL Models the MYSQL protocol.
ORACLE Models the ORACLE protocol.
CONNECTION Designates an expression that refers to network packet irrespective of flow
RADIUS Models the RADIUS message.
SERVER Designates an expression that refers to the server. This is the starting point for access into parameters such as Ether and SSL.
SIP Models the SIP protocol.
SMPP Models the SMPP protocol.
SUBSCRIBER Models the Subscriber database attributes.
SYS Designates an expression that refers to the NetScaler, rather than the client or server.
EXTEND(uint i, uint j) Extends the target area around the matched pattern.
TARGET Refers to the matched pattern.
TEXT Operates on selected text.