Installation guide

The Proxy Advertisement module, mod_advertise.so, broadcasts the existence of the proxy

server via UDP multicast messages. T he server advertisement messages contain the IP

address and port number on which the proxy is listening for responses from nodes that wish to

join the load-balancing cluster.

Note

Refer to Section 6.1, “Apache modules” for detailed information about the available modules

including user-configurable parameters.

Worker Node Component s

The JBoss HT TP Connector client service, mod-cluster.sar, is deployed on each worker node.

Worker node service : mod-cluster.sar

This service provides the proxy with real-time information on the worker node's state and

sends notification of application life-cycle events; as well as allowing the node to discover and

5.3. Limitations

The JBoss HT TP Connector mod_clust er uses shared memory to keep the nodes description, the

shared memory is created at the startup of httpd and the structure of each item is fixed. T herefore,

when defining proxy server and worker node properties, make sure to follow these character limits:

Maximum Alias length: 100 characters (Alias corresponds to the network name of the respective

virtual host; the name is defined in the Host element)

Maximum context length: 40 characters (for example, if myapp.war is deployed in /myapp, then

/myapp is the context)

Maximum balancer name length: 40 characters (the balancer property in mbean)

Maximum JVMRoute string length: 80 character (JVMRoute in the <Engine> element)

Maximum domain name length: 20 characters (the domain property in mbean)

Maximum hostname length for a node: 64 characters (hostname address in the <Connector>

element)

Maximum port length for a node: 7 characters (8009 is 4 characters, the port property in the

<Connector> element)

Maximum scheme length for a node: 6 characters (possible values are http, https, ajp, the protocol

of the connector)

Maximum cookie name length: 30 characters (the header cookie name for session ID default value:

JSESSIONID from org.apache.catalina.Globals.SESSION_COOKIE_NAME)

Maximum path name length: 30 characters (the parameter name for the session ID default value:

JSESSIONID from org.apache.catalina.Globals.SESSION_PARAMET ER_NAME)

Maximum length of a session ID: 120 characters (session ID resembles the following:

BE81FAA969BF64C8EC2B6600457EAAAA.node01)

JBoss Enterprise Application Platform 5 HTTP Connectors Load Balancing Guide 23