How service integration converts the message header fields and properties to and from WebSphere MQ format

This topic describes how service integration processes the message header fields and properties when converting messages between WebSphere® MQ format and service integration format.

Exchanging messages between JMS programs through service integration and WebSphere MQ

In general, you do not need to be aware of conversion between message formats to exchange JMS messages between service integration and WebSphere MQ. However, you might need to learn about message conversion if your JMS applications do not behave as expected or if your service integration configuration includes JMS programs or mediations that process messages to or from non-JMS WebSphere MQ programs.

If your service integration applications exchange MapMessage objects with WebSphere MQ applications, you might need to specify a non-default map message encoding format. For more information, see Setting the WebSphere MQ encoding format for JMS Map entries.

WebSphere MQ message properties: the MQMD and the MQRFH2

WebSphere MQ messages contain message properties in the message descriptor (MQMD) and in the rules and formatting header 2 (MQRFH2).

When service integration converts a message to WebSphere MQ format, it sets fields in the MQMD and the MQRFH2 based on the service integration message header fields and properties; these include JMS message header fields and properties applicable to the message. When service integration converts a message from WebSphere MQ format, it sets the service integration message header fields and properties from the MQMD and the MQRFH2 in the WebSphere MQ message.

The WebSphere MQ message always includes an MQMD, but the MQRFH2 is optional because some WebSphere MQ applications cannot process messages that contain an MQRFH2. To simplify interoperation, you can configure service integration to omit the MQRFH2 from messages for applications that cannot process the MQRFH2. When service integration omits the MQRFH2, it discards the corresponding service integration header fields and properties.
Note: A small amount of the MQRFH2 information is also stored in MQMD fields. However, these MQMD fields are not exact equivalents, tend to be less specific, and cannot be relied upon to provide an adequate substitute for the MQRFH2 information. Therefore if the receiving application can accept an MQRFH2 header, you should always provide one.

Similarly, service integration might receive messages from WebSphere MQ applications that generate messages with no MQRFH2. When service integration receives a message with no MQRFH2, it creates a "best guess" service integration header, by getting as much information as it can from the MQMD, and using default values for the other fields.

For detailed information about the contents of the message descriptor and the message headers, see the WebSphere MQ Application Programming Reference. For details of WebSphere MQ JMS support, including details of how WebSphere MQ stores JMS message properties and header fields in the MQMD and the MQRFH2, see WebSphere MQ Using Java™.

WebSphere MQ message properties: JMS header fields

The following table shows how service integration maps JMS header fields to and from MQMD and MQRFH2 fields when converting messages to and from WebSphere MQ format.

The table shows the MQRFH2 field as folder.field, where folder is the name of the MQRFH2 folder which contains the field, and field is the name of the field within the MQRFH2 folder.

For several JMS header fields, there is both an MQMD field and an MQRFH2 field. When service integration is converting messages to WebSphere MQ format, it sets both the MQMD and the MQRFH2 fields; when service integration is converting messages from WebSphere MQ format, it sets the JMS header field from the MQRFH2 field if it is available, otherwise from the MQMD field.

Table 1. Mapping JMS header fields to MQMD and MQRFH2 fields
JMS header field MQMD field MQRFH2 field Notes®
JMSCorrelationID CorrelId jms.Cid The MQMD CorrelId field can hold a standard WebSphere MQ Correlation ID of 48 hexadecimal digits (24 bytes). The JMSCorrelationID can be a byte[] value, a string value containing hexadecimal characters and prefixed with "ID:", or an arbitrary string value not beginning "ID:". The first two of these represent a standard WebSphere MQ Correlation ID and map directly to or from the MQMD CorrelId field (truncated or padded with zeros as applicable); they do not use the MQRFH2 jms.Cid field. The third (arbitrary string) uses the MQRFH2 jms.Cid field; the first 24 bytes of the string, in UTF-8 format, are written into the MQMD CorrelID.
JMSDeliveryMode Persistence jms.Dlv  
JMSDestination   jms.Dst  
JMSExpiration Expiry jms.Exp  
JMSMessageID MsgId    
JMSPriority Priority   WebSphere MQ stores the JMSPriority value in the MQRFH2 jms.Pri field but does not use any value already in that field. Service integration does not check or set the MQRFH2 jms.Pri field.
JMSRedelivered BackoutCount   Service integration sets the JMSRedelivered indicator for a message it receives form WebSphere MQ based on the BackoutCount field of the MQMD; a non-zero BackoutCount value indicates that a previous receive for the message was rolled back.
JMSReplyTo ReplyToQ and ReplyToQMgr jms.Rto
JMSTimestamp PutDate and PutTime jms.Tms  
JMSType   mcd.Type  

WebSphere MQ message properties: JMS defined properties

The following table shows how service integration maps JMS defined properties to and from MQMD and MQRFH2 fields when converting messages to and from WebSphere MQ format.

The table shows the MQRFH2 field as folder.field, where folder is the name of the MQRFH2 folder which contains the field, and field is the name of the field within the MQRFH2 folder.

For several JMS-defined properties, there is both an MQMD field and an MQRFH2 field. When service integration is converting messages to WebSphere MQ format, it sets both the MQMD and the MQRFH2 fields; when service integration is converting messages from WebSphere MQ format, it sets the JMS defined property from the MQRFH2 field if it is available, otherwise from the MQMD field.

Table 2. Mapping JMS defined properties to MQMD and MQRFH2 fields
JMS defined property MQMD field MQRFH2 field Notes
JMSXAppID PutApplName    
JMSXDeliveryCount BackoutCount    
JMSXGroupID GroupId jms.Gid The MQMD GroupId field can hold a standard WebSphere MQ GroupId of 48 hexadecimal digits (24 bytes). The JMSXGroupID is a string value containing hexadecimal characters and prefixed with "ID:" or an arbitrary string value not beginning "ID:". The first of these represents a standard WebSphere MQ GroupId and maps directly to or from the MQMD GroupId field (truncated or padded with zeros as applicable). The second (arbitrary string) uses the MQRFH2 jms.Gid field; the first 24 bytes of the string, in UTF-8 format, are written into the MQMD GroupId.

When service integration is converting messages to WebSphere MQ format, if the JMSXGroupID has been set then service integration also sets the MQMF_MSG_IN_GROUP flag in the MsgFlags field of the MQMD. Note that when sending group messages, the sending JMS application must ensure that the MQMF_LAST_MSG_IN_GROUP flag is set as required (see WebSphere MQ message properties: JMS provider-specific properties).

JMSXGroupSeq MsgSeqNumber jms.Seq  
JMSXUserID UserIdentifier    

WebSphere MQ message properties: JMS provider-specific properties

The following table shows how service integration maps JMS provider-specific properties to and from MQMD and MQRFH2 fields when converting messages to and from WebSphere MQ format. Typically you use these properties to satisfy special requirements in the receiving application, so you should consult the developer or administrator of the receiving application for details of the required property values.

The table shows the MQRFH2 field as folder.field, where folder is the name of the MQRFH2 folder which contains the field, and field is the name of the field within the MQRFH2 folder.

Table 3. Mapping JMS provider-specific properties to MQMD and MQRFH2 fields
JMS provider-specific property MQMD field MQRFH2 field Notes
JMS_IBM_Character_Set CodedCharacterSetId CodedCharacterSetId
Note 1: The JMS_IBM_Character_Set, JMS_IBM_Encoding, and JMS_IBM_Format properties contain information about the WebSphere MQ message payload; that is, the part of the WebSphere MQ message that follows the MQRFH2 (if there is one) or the whole WebSphere MQ message, excluding the MQMD, if there is no MQRFH2. For more information about these properties and how to use them, see How service integration converts the message body to and from WebSphere MQ format.
JMS_IBM_Encoding Encoding Encoding

See Note 1.

JMS_IBM_Feedback Feedback    
JMS_IBM_Format Format Format

See Note 1.

JMS_IBM_Last_Msg_In_Group MQMF_LAST_MSG_IN_GROUP  
Note 2: MQMF_LAST_MSG_IN_GROUP is one of the flags in the MsgFlags field of the MQMD.
JMS_IBM_MsgType MsgType    
JMS_IBM_PutDate PutDate    
JMS_IBM_PutTime PutTime    
JMS_IBM_Report_* Report  
Note 3: For a list of the JMS_IBM_Report_* properties, see Mapping of MQMD Report fields to JMS provider-specific properties.



Related concepts
Point-to-point messaging with a WebSphere MQ network
Related tasks
Specifying whether messages are forwarded to WebSphere MQ as JMS messages
Related reference
Mapping messages between a WebSphere service integration bus and WebSphere MQ
Reference topic    

Terms of Use | Feedback

Last updated: Aug 29, 2010 9:31:45 PM CDT
http://www14.software.ibm.com/webapp/wsbroker/redirect?version=vela&product=was-nd-mp&topic=rjc0007_
File name: rjc0007_.html