NetScaler has rich feature sets which move it up from just being a vanilla Load Balancer. Looking at the numerous features across all the layers, NetScaler has the ability to control and handle traffic in every possible way. Today the Layer7 world has grown much beyond with smart Web2.0 tools and techniques and thus the way NetScaler looks at traffic needed change at the internal architecture level. This is where AppExpert framework was introduced which has following features:

• Extremely powerful expression language spanning from Layer1 to Layer7. You can define all possible expressions getting to the most atomic level as per protocol RFCs.

• The expression language can be used to define Rules in Policy, define different parts of Actions, and any other entity supported over AppExpert like HTTP Callout, Rate Limit Identifiers etc.

• Expression language can parse through any part of http/s request and response

• Single policy or action can have multiple expressions to allow better logical use cases

• Same policy can combine expressions from multiple layers as far as they logically fit well

• Provides multiple bind points for policies – default, override, vserver

• Same Policy can be bound to multiple bind points

• Framework can be used from most of the features in NS
Load Balancing
Content Switching
Integrated Caching
Application Firewall
Responder
Rewrite
SSLVPN
Compression
Rate Limiting
HTTP Callout