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| <!DOCTYPE document [ |
| <!ENTITY project SYSTEM "project.xml"> |
| ]> |
| <document url="cluster-valve.html"> |
| |
| &project; |
| |
| <properties> |
| <author email="fhanik@apache.org">Filip Hanik</author> |
| <title>The Cluster Valve object</title> |
| </properties> |
| |
| <body> |
| |
| <section name="Table of Contents"> |
| <toc/> |
| </section> |
| |
| <section name="Introduction"> |
| <p> |
| A cluster valve is no different from any other <a href="valve.html">Tomcat <code>Valve</code></a>. |
| The cluster valves are interceptors in the invocation chain for HTTP requests, and the clustering implementation |
| uses these valves to make intelligent decision around data and when data should be replicated. |
| </p> |
| <p> |
| A cluster valve must implement the <code>org.apache.catalina.ha.ClusterValve</code> interface. |
| This is a simple interface that extends the <code>org.apache.catalina.Valve</code> interface. |
| </p> |
| </section> |
| |
| <section name="org.apache.catalina.ha.tcp.ReplicationValve"> |
| The <code>ReplicationValve</code> will notify the cluster at the end of a HTTP request |
| so that the cluster can make a decision whether there is data to be replicated or not. |
| <subsection name="Attributes"> |
| <attributes> |
| <attribute name="className" required="true"> |
| Set value to <code>org.apache.catalina.ha.tcp.ReplicationValve</code> |
| </attribute> |
| <attribute name="filter" required="false"> |
| For known file extensions or urls, you can use this Valve to notify the |
| cluster that the session has not been modified during this request and |
| the cluster doesn't have to probe the session managers for changes. If |
| the request matches this filter pattern, the cluster assumes there has |
| been no session change. An example filter would look like <code> |
| filter=".*\.gif|.*\.js|.*\.jpeg|.*\.jpg|.*\.png|.*\.htm|.*\.html|.*\.css|.*\.txt" |
| </code>. The filter is a regular expression using |
| <code>java.util.regex</code>. |
| </attribute> |
| <attribute name="primaryIndicator" required="false"> |
| Boolean value, so to true, and the replication valve will insert a request attribute with the name |
| defined by the <code>primaryIndicatorName</code> attribute. |
| The value inserted into the request attribute is either <code>Boolean.TRUE</code> or |
| <code>Boolean.FALSE</code> |
| </attribute> |
| <attribute name="primaryIndicatorName" required="false"> |
| Default value is <code>org.apache.catalina.ha.tcp.isPrimarySession</code> |
| The value defined here is the name of the request attribute that contains the boolean value |
| if the session is primary on this server or not. |
| </attribute> |
| <attribute name="statistics" required="false"> |
| Boolean value. Set to <code>true</code> if you want the valve to collect request statistics. |
| Default value is <code>false</code> |
| </attribute> |
| </attributes> |
| </subsection> |
| </section> |
| |
| <section name="org.apache.catalina.ha.session.JvmRouteBinderValve"> |
| In case of a mod_jk failover, the <code>JvmRouteBinderValve</code> will replace the |
| <code>jvmWorker</code> attribute in the session Id, to make future requests stick to this |
| node. If you want failback capability, don't enable this valve, but if you want your failover to stick, |
| and for mod_jk not to have to keep probing the node that went down, you use this valve. |
| <subsection name="Attributes"> |
| <attributes> |
| <attribute name="className" required="true"> |
| <code>org.apache.catalina.ha.session.JvmRouteBinderValve</code> |
| </attribute> |
| <attribute name="enabled" required="false"> |
| Default value is <code>true</code> |
| Runtime attribute to turn on and off turn over of the session's jvmRoute value. |
| </attribute> |
| <attribute name="sessionIdAttribute" required="false"> |
| Old sessionid before failover is registered in request attributes with this attribute. |
| Default attribute name is <code>org.apache.catalina.ha.session.JvmRouteOrignalSessionID</code>. |
| </attribute> |
| </attributes> |
| </subsection> |
| </section> |
| |
| |
| </body> |
| |
| </document> |
