Using JDG as External Cache Container for WildFly HTTP Session Replication

External

• Externalizing Sessions with JDG https://access.redhat.com/documentation/en-US/Red_Hat_JBoss_Data_Grid/6.6/html/Administration_and_Configuration_Guide/chap-Externalize_Sessions.html

Internal

• WildFly Infinispan HTTP Session Replication Configuration

Relevance

• EAP 6.5, JDG 6.6

Overview

JDG can be used as an external cache container for HTTP session data within WildFly. This allows scaling of the data layer independent of the application, and enables different WildFly clusters, that may reside in various domains, to access data from the same JDG cluster.

Setup the JDG Cluster

Configuration details are available here: Infinispan Configuration. The external JDG cluster will be accessed by the WildFly instance over the HotRod protocol.

Define a dedicated cache for each web application In this specific case, the dedicated cache name is "jdg-http-sessions":

<subsystem xmlns="urn:infinispan:server:core:6.4">
  <cache-container name="clustered" default-cache="default" statistics="true">
    <transport executor="infinispan-transport" lock-timeout="60000"/>
    <distributed-cache name="default" ...>
      ...
    </distributed-cache>
    <distributed-cache name="jdg-http-sessions" owners="2" mode="SYNC" start="EAGER"/>
  </cache-container>
  ...
</subsystem>

Configure the WildFly Cache

For each distributable application, an entirely new WildFly cache must be created.

The first one can be created reconfiguring the existing 'web cache container. All other cache containers/caches can be removed.

        <subsystem xmlns="urn:jboss:domain:infinispan:1.5">
            <cache-container name="web" aliases="standard-session-cache" default-cache="repl" module="org.jboss.as.clustering.web.infinispan">
                <transport lock-timeout="60000"/>
                <replicated-cache name="repl" mode="ASYNC" batching="true">
                    <remote-store cache="jdg-http-sessions" socket-timeout="60000" tcp-no-delay="true" shared="true" preload="false" passivation="false" fetch-state="false" purge="false">
                        <remote-server outbound-socket-binding="initial-jdg-server"/>
                    </remote-store>
                </replicated-cache>
            </cache-container>
        </subsystem>

Remote Cache preload Setting

The preload setting should be false, because If the store is configured to preload the cache, when the cache starts all data stored in the store will be pre-loaded into memory, This is rarely what we want. Clustered HTTP caches are usually large, exceeding the capacity of heap, and there's no point in loading all the HTTP sessions from the distributed cache into the memory of a node, anyway.

For more details on preload, see Cache Store Preloading.

Startup Options

The JDG-backed infinispan cache starts lazily with the default configuration. That mean it will only connect to the JDG cluster when a distributable web application is deployed. Sometimes might be desirable to start the cache and connect to the JDG server as soon as the WildFly server boots. To achieve that, configure the cache to start "EAGER":

    ...
    <replicated-cache name="repl" mode="ASYNC" batching="true" start="EAGER">
        ... 
    </replicated-cache>
    ...

Declare the Outbound Socket

    <socket-binding-group name="standard-sockets" default-interface="public" port-offset="${jboss.socket.binding.port-offset:0}">
        ...
        <outbound-socket-binding name="initial-jdg-server">
            <remote-destination host="localhost" port="11222"/>
        </outbound-socket-binding>
    </socket-binding-group>

Configura the Application to be Distributable

web.xml, jboss-web.xml.