List of broker addresses

The list consists of one or more addresses, separated by commas. Each address specifies (or implies) the host name, port number, and connection service for a broker instance to which the client can connect. Address syntax varies depending on the connection service and port assignment method; see below for details.

Literal IP addresses as host names: You can use a literal IPv4 or IPv6 address as a host name. If you use a literal IPv6 address, its format must conform to RFC2732, Format for Literal IPv6 Addresses in URL’s.

Note: In an enhanced broker cluster, the value of this attribute is updated dynamically as brokers enter and leave the cluster, so that it always reflects the cluster’s current membership.

Order in which to attempt connection to broker addresses:

Note: If many clients share the same connection factory, specify random connection order to prevent them from all attempting to connect to the same address.

Number of times to iterate through address list attempting to establish or reestablish a connection

A value of -1 denotes an unlimited number of iterations.

Note: In the event of broker failure in an enhanced broker cluster, this attribute is ignored and the Message Queue client runtime iterates through the address list indefinitely until it succeeds in reconnecting to a takeover broker. The effect is equivalent to an imqAddressListIterations value of -1, overriding any other explicit or default setting of this attribute. The only way for a client application to avoid this behavior is to close the connection explicitly on broker failure.

Interval, in seconds, at which to test connection between client and broker

A value of 0 or -1 disables periodic testing of the connection.

Attempt to reestablish a lost connection?

Note: In the event of broker failure in an enhanced broker cluster, this attribute is ignored and automatic reconnection is always attempted. The effect is equivalent to an imqReconnectEnabled value of true, overriding any other explicit or default setting of this attribute. The only way for a client application to avoid this behavior is to close the connection explicitly on broker failure.

Number of times to attempt connection (or reconnection) to each address in address list before moving on to next

A value of -1 denotes an unlimited number of connection attempts: attempt repeatedly to connect to first address until successful. For example, in an enhanced broker cluster, this value will allow for connection to the failover broker.

Interval, in milliseconds, between reconnection attempts

This value applies both for successive attempts on a given address and for successive addresses in the list.

Note: Too small a value may give the broker insufficient recovery time; too large a value may cause unacceptable connection delays.

Socket timeout, in milliseconds, used when a TCP connection is made to the broker

This value applies when connecting to the port mapper as well as when connecting to the required service.

The timeout value 0 (zero) denotes an infinite timeout, in which case the connection will block until it is established or an error occurs.

Trust any certificate presented by broker?

If false, the Message Queue client runtime will validate all certificates presented to it. Validation will fail if the signer of the certificate is not in the client’s trust store.

If true, validation of certificates is skipped. This can be useful, for instance, during software testing when a self-signed certificate is used.

Assign port dynamically for jms or ssljms connection service

The address list entry specifies the host name and port number for the Message Queue Port Mapper. The Port Mapper itself dynamically assigns a port to be used for the connection.

Default values:

For the ssljms connection service, all variables must be specified explicitly.

Literal IP addresses as host names: You can use a literal IPv4 or IPv6 address as a host name. If you use a literal IPv6 address, its format must conform to RFC2732, Format for Literal IPv6 Addresses in URL’s.

Connect to specified port using jms connection service

Bypasses the Port Mapper and makes a TCP connection directly to the specified host name and port number.

Connect to specified port using ssljms connection service

Bypasses the Port Mapper and makes a secure SSL connection directly to the specified host name and port number.

http://`hostName:portNumber/contextRoot/tunnel`

If multiple broker instances use the same tunnel servlet, the following syntax connects to a specific broker instance rather than a randomly selected one:

http://`hostName:portNumber/contextRoot/tunnel?`

Connect to specified port using httpjms connection service

Makes an HTTP connection to a Message Queue tunnel servlet at the specified URL. The broker must be configured to access the HTTP tunnel servlet.

https://`hostName:portNumber/contextRoot/tunnel`

If multiple broker instances use the same tunnel servlet, the following syntax connects to a specific broker instance rather than a randomly selected one:

https://`hostName:portNumber/contextRoot/tunnel?`

Connect to specified port using httpsjms connection service

Makes a secure HTTPS connection to a Message Queue tunnel servlet at the specified URL. The broker must be configured to access the HTTPS tunnel servlet.

Should the connection to the broker be aborted when imqPingAckTimeout milliseconds have passed?

If the connection is aborted, the Message Queue Client Runtime operates as though the connection to the broker were broken.

Maximum time, in milliseconds, to wait for broker acknowledgment before throwing an exception

A value of 0 denotes no timeout (wait indefinitely).

Note: In some situations, too low a value can cause premature timeout: for example, initial authentication of a user against an LDAP user repository using a secure (SSL) connection can take more than 30 seconds.

Number of payload messages in a metered batch

Delivery of payload messages to the client is temporarily suspended after this number of messages, allowing any accumulated control messages to be delivered. Payload message delivery is resumed on notification by the client runtime, and continues until the count is again reached.

A value of 0 disables metering of message delivery and may cause Message Queue control messages to be blocked by heavy payload message traffic.

Maximum number of messages per connection to deliver and buffer for consumption

Message delivery on a connection stops when the number of unconsumed payload messages pending (subject to flow metering governed by imqConnectionFlowCount) exceeds this limit. Delivery resumes only when the number of pending messages falls below the limit. This prevents the client from being overwhelmed with pending messages that might cause it to run out of memory.

This attribute is ignored if imqConnectionFlowLimitEnabled is false.

Is message prefetching and buffering as specified by imqConsumerFlowLimit and imqConsumerFlowThreshold enabled?

When set to false, message prefetching and buffering is disabled, and each consumer is delivered one message at a time, which can give rise to a number of performance issues.

This property should be set to false only when business logic demands that each consumer have only one message at a time.

Maximum number of messages per consumer to deliver and buffer for consumption

Message delivery to a given consumer stops when the number of unconsumed payload messages pending for that consumer exceeds this limit. Delivery resumes only when the number of pending messages for the consumer falls below the percentage specified by imqConsumerFlowThreshold. This can be used to improve load balancing among multiple consumers and prevent any single consumer from starving others on the same connection.

A value of 0 or -1 denotes an unlimited number of messages.

This limit can be overridden by a lower value set for a queue’s own consumerFlowLimit attribute (see Physical Destination Property Reference). Note also that message delivery to all consumers on a connection is subject to the overall limit specified by imqConnectionFlowLimit.

Maximum time, in milliseconds, to wait for a ping reply or any data sent from the broker since its last ping reply or data sent.

A value of 0 denotes no timeout (wait indefinitely).

This value is ignored if the imqAbortOnPingAckTimeout attribute is set to false.

Maximum number of messages to retrieve at one time when browsing contents of a queue destination

Note: This attribute does not affect the total number of messages browsed, only the way they are chunked for delivery to the client runtime (fewer but larger chunks or more but smaller ones). The client application will always receive all messages in the queue. Changing the attribute’s value may affect performance, but will not affect the total amount of data retrieved.

Load up to maximum number of messages into a server session?

If false, the client will load only a single message at a time.

This attribute applies only to JMS application server facilities.

Overriding value of delivery mode:

1 Nonpersistent

2 Persistent

Overriding value of expiration time, in milliseconds

A value of 0 denotes an unlimited expiration time (message never expires).