External cache group settings | Modify the DynaCache configuration file

Reconfigure the Web servers

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For ESI caching to work properly in the IBM HTTP Server Plug-in, including receiving invalidations from the application servers, you need to change the plug-in configuration file on each Web server.

Below shows the beginning of the file with ESI caching and invalidations enabled for a maximum cache size of 512 MB.

<?xml version-"1.0"?>
<Config ...>
   ...
   <Property Name="esiEnable" Value="true"/>
   <Property Name="esiMaxCacheSize" Value="524288"/>
   <Property Name="esiInvalidationMonitor" Value="false"/>
   ...
</Config>

Note the following:

esiEnablexxxx	To disable the ESI processor set value to false. ESI is enabled by default. If ESI is disabled, then the other ESI options are ignored.
esiMaxCacheSizexxxx	Maximum size of the cache in 1 KB units. The default maximum size of the cache is 1 MB (1,024 KB). If the cache is full, the first entry to be evicted from the cache is the entry that is closest to expiration.
esiInvalidationMonitorxxxx	Whether the ESI processor should receive invalidations from the application server. ESI works well when the Web servers following a threading model are used, and only one process is started. When multiple processes are started, each process caches the responses independently and the cache is not shared. This could lead to a situation where the system's memory is fully used up by the ESI processor.

There are three methods by which entries are removed from the ESI cache:

• An entry's expiration timeout could fire.
• An entry may be purged to make room for newer entries
• The application server could send an explicit invalidation for a group of entries.

For the third mechanism to be enabled, the esiInvalidationMonitor property must be set to true and the DynaCacheEsi application must be installed on the application server.

To configure the plug-in on all Web servers, for each of your Web servers...

1. In the administrative console, navigate to...

   Servers | Web servers | <WebServer_Name> | Plug-in properties | Caching

2. To cache responses, activate...

   Enable Edge Side Includes (ESI) processing to cache responses

   To receive navigations, activate...

   Enable invalidation monitor to receive notifications...

   ...and enter your desired maximum cache size (this is per ESI processor process).

   

3. Click OK.

4. Save your changes to the master configuration.

   After performing the steps above for each of your Web servers, you need to propagate the plug-in configuration file, plugin-cfg.xml.

   You do not need to explicitly propagate the plug-in configuration file if you make all of the following settings:

   • Activate both automatic plug-in configuration generation and propagation

   • Enable remote Web server management for your Web servers.

     Supply an administrative user name and password to Network Deployment Manager, and start IHS administrative server on the Web servers.

You may still perform the following steps if you have remote Web server management enabled and if the administrative server is running on your Web servers, for example, if you do not want to wait until the plug-in configuration is refreshed automatically, or if automatic generation and propagation are switched off.

1. Navigate to...

   Servers | Web servers

2. Select all of your Web servers that have remote Web server management enabled.

   

3. Click Generate Plug-in, then Propagate Plug-in.

   If remote Web server management is not enabled, you need to copy the plug-in configuration file manually to your Web servers (see Propagate IBM HTTP Server Plug-in configuration).

   After propagating the plug-in configuration, stop and start your Web servers. Testing ESI caching simply reloading the plugin-cfg.xml file is not enough, and a real stop and start of the Web servers is necessary to activate ESI caching and invalidation handling.