Connection Failover

The use of Message Queue broker clusters provides JMS connection failover, including several options that control how connection failures are handled.

Use the Administration Console's Java Message Service page to configure these options. To display this page, click the configuration for the GlassFish cluster or instance in the navigation pane, and then click the Java Message Service link on the Configuration page.

The way in which connection failover operates depends on whether the broker cluster is configured to be conventional or enhanced:

• In a conventional cluster, when a broker fails, clients may reconnect to any other broker in the cluster. The Reconnect field specifies whether reconnection should take place, and the Address List Behavior and Address List Iterations fields specify how the client chooses what broker to fail over to.

• In an enhanced cluster, when a broker fails, another broker automatically takes over its messages and clients. Clients automatically fail over to the appropriate broker. The Reconnect, Address List Behavior and Address List Iterations fields are ignored.

For more information on connection failover, including how failover on conventional clusters differs from failover on enhanced clusters, see Automatic Reconnection in Oracle GlassFish Server Message Queue 4.5 Administration Guide.

Reconnect

Applies only to conventional clusters. Enables reconnection and connection failover. When disabled, the Java Message Service does not attempt to reconnect if a connection fails.

Reconnect Interval

Specifies the number of seconds between reconnection attempts. If it is too short, this time interval does not give a broker time to recover. If it is too long, the wait time might represent an unacceptable delay. The default value is 5 seconds.

Reconnect Attempts

Specifies the number of attempts to connect (or reconnect) to a particular JMS host before trying another host in the JMS host list. The host list is also known as the Address List. Hosts are chosen from the address list either in order or randomly, depending on the setting of Address List Behavior.

Address List Behavior

For conventional clusters, this field specifies how the Java Message Service selects which JMS host in the JMS hosts list to initially connect to, and if the broker fails, how the Java Message Service selects which JMS host in the JMS hosts list to fail over to.

For enhanced clusters, this field specifies how the Java Message Service selects which JMS host in the JMS hosts list to initially connect to.

When performing initial connection or, for conventional clusters only, when performing failover, then if this attribute is set to Priority, the Java Message Service tries to connect to the first JMS host specified in the JMS hosts list and uses another one only if the first one is not available. If this attribute is set to Random, the Java Message Service selects the JMS host randomly from the JMS hosts list. If that host is not available, another one is chosen randomly.

The default for Embedded and Local JMS host types is Priority, and the default for the Remote JMS host type is Random.

For Embedded and Local JMS host types, the Java Message Service ensures that the Message Queue broker servicing a clustered instance appears first in that instance's JMS host list.

Thus, having Priority as the default Address List Behavior ensures that an application deployed to a clustered instance will always try to create its initial connection to that instance's co-located broker.

If there are many clients attempting a connection using the same connection factory, use the Random setting to prevent them from all attempting to create their initial connection to the same JMS host.

Address List Iterations

For conventional clusters, this field specifies the number of times the Java Message Service iterates through the JMS hosts list in an effort to establish its initial connection. If the broker fails, this field specifies the number of times the Java Message Service iterates through the JMS hosts list in an effort to fail over to another broker.

For enhanced clusters, this field specifies the number of times the Java Message Service iterates through the JMS hosts list in an effort to establish its initial connection. If the broker fails, this field is not used when performing reconnection.

You can override these settings using JMS connection factory settings. For details, see Administering JMS Connection Factories and Destinations in Oracle GlassFish Server 3.1 Administration Guide.