Caching Proxy support of the NoCacheOnRange directive
 Technote (troubleshooting)
 
Problem(Abstract)
This technote provides information on the NoCacheOnRange directive.

The minimum release levels that support this directive are: 4.0.2.57, 5.0.2.36, 5.1.1.10, 6.0.2.0.

By default, when receiving a Range request from browsers, Caching Proxy requires a full response from the back-end server. Caching Proxy removes the Range header in the request and then forwards the request to the back-end server. After the response is cached on the proxy server, the subsequent requests for the same resources are served from the proxy server, regardless of whether the requests are Range requests or not.

Usually, the default action of Caching Proxy improves performance and gives clients shorter response times. However, if the response cannot be cached, or if the response is very large, the default action decreases performance.
 
Resolving the problem
Use the NoCacheOnRange directive, which specifies no caching for Range requests, to solve the problem that is described when using the default configuration.
When you enable the directive globally in the ibmproxy.conf file, or if you enable it as an option for the PROXY mapping rule, Caching Proxy forwards the Range request-header to the back-end server. Caching Proxy does not cache the 206 (partial content) response from the back-end server.

The NoCacheOnRange directive can improve the proxy performance for the following cases:

  • The responses cannot be cached or updated frequently.
  • The response time is critical for the application.

Syntax:
NoCacheOnRange [on | off]

Default:
off

You can also enable NoCacheOnRange in a proxy mapping rule; for example:
Proxy  /not-cachable/*   http://server.com/no-cachable-resources/*   NoCacheOnRange
 
 
Cross Reference information
Segment Product Component Platform Version Edition
Application Servers WebSphere Edge Server Caching Proxy Multi-Platform Edge Server 2.0 PTF2
Application Servers Runtimes for Java Technology Java SDK
 
 


Document Information


Product categories: Software > Application Servers > Distributed Application & Web Servers > WebSphere Application Server > Edge Component
Operating system(s): Windows
Software version: 6.0.2
Software edition:
Reference #: 1217778
IBM Group: Software Group
Modified date: Sep 8, 2005