Mapping JMS header fields at send() or publish()

Mapping JMS header fields at send() or publish()

The following notes relate to the mapping of JMS fields at send() or publish():

JMSDestination to MQRFH2

This is stored as a string that serializes the salient characteristics of the destination object, so that a receiving JMS can reconstitute an equivalent destination object. The MQRFH2 field is encoded as URI (see uniform resource identifiers for details of the URI notation).

JMSReplyTo to MQMD ReplyToQ, ReplyToQMgr, MQRFH2

The queue and queue manager name are copied to the MQMD ReplyToQ and ReplyToQMgr fields respectively. The destination extension information (other useful details that are kept in the destination object) is copied into the MQRFH2 field. The MQRFH2 field is encoded as a URI (see uniform resource identifiers for details of the URI notation).

JMSDeliveryMode to MQMD Persistence

The JMSDeliveryMode value is set by the send() or publish() Method or MessageProducer, unless the Destination Object overrides it. The JMSDeliveryMode value is mapped to the MQMD Persistence field as follows:

JMS value PERSISTENT is equivalent to MQPER_PERSISTENT
JMS value NON_PERSISTENT is equivalent to MQPER_NOT_PERSISTENT
If the MQQueue persistence property is not set to JMSC.MQJMS_PER_QDEF, the delivery mode value is also encoded in the MQRFH2.

JMSExpiration to/from MQMD Expiry, MQRFH2

JMSExpiration stores the time to expire (the sum of the current time and the time to live), whereas MQMD stores the time to live. Also, JMSExpiration is in milliseconds, but MQMD.expiry is in centiseconds.

If the send() method sets an unlimited time to live, MQMD Expiry is set to MQEI_UNLIMITED, and no JMSExpiration is encoded in the MQRFH2.
If the send() method sets a time to live that is less than 214748364.7 seconds (about 7 years), the time to live is stored in MQMD. Expiry, and the expiration time (in milliseconds), are encoded as an i8 value in the MQRFH2.
If the send() method sets a time to live greater than 214748364.7 seconds, MQMD.Expiry is set to MQEI_UNLIMITED. The true expiration time in milliseconds is encoded as an i8 value in the MQRFH2.

JMSPriority to MQMD Priority

Directly map JMSPriority value (0-9) onto MQMD priority value (0-9). If JMSPriority is set to a non-default value, the priority level is also encoded in the MQRFH2.

JMSMessageID from MQMD MessageID

All messages sent from JMS have unique message identifiers assigned by WebSphere MQ. The value assigned is returned in the MQMD messageId field after the MQPUT call, and is passed back to the application in the JMSMessageID field. The WebSphere MQ messageId is a 24-byte binary value, whereas the JMSMessageID is a string. The JMSMessageID is composed of the binary messageId value converted to a sequence of 48 hexadecimal characters, prefixed with the characters ID:. JMS provides a hint that can be set to disable the production of message identifiers. This hint is ignored, and a unique identifier is assigned in all cases. Any value that is set into the JMSMessageId field before a send() is overwritten.

JMSTimestamp to MQRFH2

During a send, the JMSTimestamp field is set according to the JVM's clock. This value is set into the MQRFH2. Any value that is set into the JMSTimestamp field before a send() is overwritten. See also the JMS_IBM_PutDate and JMS_IBM_PutTime properties.

JMSType to MQRFH2

This string is set into the MQRFH2 mcd.Type field. If it is in URI format, it can also affect mcd.Set and mcd.Fmt fields. See also Connecting to other products.

JMSCorrelationID to MQMD CorrelId, MQRFH2

The JMSCorrelationID can hold one of the following:

A provider specific message ID

This is a message identifier from a message previously sent or received, and so should be a string of 48 hexadecimal digits that are prefixed with ID:. The prefix is removed, the remaining characters are converted into binary, and then they are set into the MQMD CorrelId field. No CorrelId value is encoded in the MQRFH2.

A provider-native byte[] value

The value is copied into the MQMD CorrelId field - padded with nulls, or truncated to 24 bytes if necessary. No CorrelId value is encoded in the MQRFH2.

An application-specific string

The value is copied into the MQRFH2. The first 24 bytes of the string, in UTF8 format, are written into the MQMD CorrelID.

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