The message headers

A message header is a part of a message that contains information used to process the message, but that is not part of the message body. Like all IBM MQ messages, an FTM SWIFT message has a standard IBM MQ message descriptor (MQMD) header, but it also has an additional header called an IBM MQ rules and formatting header 2 (MQRFH2):
  • The MQMD contains information specific to IBM MQ. It contains the control information needed to handle the exchange of messages between applications and FTM SWIFT. Parts of the MQMD are interpreted by FTM SWIFT to define its processing, for example:
    • The message type (MQMD.MsgType)
    • The message ID (MQMD.MsgId)
    • The user associated with the message (MQMD.UserIdentifier)
    • The application associated with the message (MQMD.PutApplName)
    • The target queue and queue manager for reply messages (MQMD.ReplyToQ and MQMD.ReplyToQMgr)
    • Correlation information that enables applications to correlate requests and replies (MQMD.MsgId and MQMD.CorrelId)
    • Report options to specify the requested reports.
  • The MQRFH2 contains information specific to the message broker product. Folders in the MQRFH2 contain the control information that FTM SWIFT services require to perform their specific functions.

    The MQRFH2 can contain any number of folders. Each folder has a NameValueData field (which contains the data in the folder) and a NameValueLength field (which specifies the length of the data in the NameValueData field). This is common in broker messages and is described in IBM Documentation for Message Broker.

    An application can store the following information in this header:
    • FTM SWIFT attributes of the message.
    • FTM SWIFT service requests and responses. This can be, for example, requests to record audit data or events, or requests created as a result of configuration commands, and their corresponding responses.
    • Properties that represent configuration parameters relevant for the processing of the message. These properties are provided by one of the configuration-data provider nodes (DniConfigProvider or DniSelConfigProvider) during processing, and applications can access them.
    The application that calls the service must store this information in the following folders:
    mcd
    The message content descriptor, which describes:
    • Which parser is to parse the message body
    • Which message type and format that parser is to use
    This information might be required by a service that processes a message, for example, a node that is to route a message based on the contents of its body.
    psc
    Publish or subscribe commands to be processed.
    pscr
    Responses to publish or subscribe commands.
    usr
    Application-defined or user-defined properties.
    ComIbmDni
    This folder contains the information that FTM SWIFT needs to process a message and to perform the requested action. It is described in ComIbmDni folders.
    Notes:
    1. The MQRFH2 consists of a variable section, which contains a folder structure, and a fixed section, which describes the variable section. The variable section is called NameValueData, and its CCSID is specified by the NameValueCCSID field which must be set to 1208 (UTF-8).
    2. Although the format of the MQRFH2 is similar to XML, the MQRFH2 cannot contain comments. For example, the following XML comment would produce an error: 
      <!-- this is a comment -->
Table 1 describes the fields and folders of the MQMD and MQRFH2 of an FTM SWIFT message, and shows examples of typical field values.
Table 1. Fields and folders of MQMD and MQRFH2
  Field Sample field values Description and comments
MQMD fields MsgId SENDQMGR123 A unique message identifier byte sequence. IBM MQ usually fills this field.
UserIdentifier SHR The user identifier of the application that originated this message.
CorrelId SENDQMGR123 The message identifier of the request message for FTM SWIFT response/report messages.
ReplyToQ CMQ.B7DDB69181268940 The name of the message queue to which the application receiving this message sends the reply.
MsgType MQMT_REQUEST The numeric value indicating the type of this message. Here, it is a request that requires a reply.
PutApplName SHR3 The name of the application that sends this message to FTM SWIFT. IBM MQ fills this field.
Priority 0 A number from 0 - 9 that specifies the priority of the message. Except for the SIPN FIN and MSIF transfer services, all FTM SWIFT services ignore this field. The SIPN FIN and MSIF transfer service process messages with a higher priority before those with a lower priority. If more than one message has the highest priority, they process the one that was in the input queue the longest.
Encoding MQENC_NATIVE The numeric encoding of numeric data in the section following the MQMD. Here, it is the MQRFH2 structure.
CodedCharSetId 500 The character set identifier of the message section following the MQMD. Here, it is the MQRFH2 structure.
Format MQRFH2 The format name of data that follows the message descriptor. Here, it indicates that the MQRFH2 Version2 rules and formatting header follow the message descriptor MQMD.
MQRFH2 fields StrucLength length The total length, in bytes, of the MQRFH2 structure, including the folders it contains.
CodedCharSetId 500 The coded character set identifier (CCSID) of the data that follows this header (usually the message body).
Format MQFMT_STRING A constant that indicates the format of the data contained in the body of the message:
MQFMT_STRING
The body contains a character string. This constant corresponds to the value: 
'MQSTR   '
(MQSTR followed by 3 trailing blanks)
MQFMT_NONE
The body contains data that is not a character string (for example, binary data), or is empty. This constant corresponds to the value: 
'        '
(8 blanks)
NameValueCCSID 1208 The character set identifier of data in the NameValueData field (the mcd or ComIbmDni folder content). Set the value to 1208 ("UTF-8").
mcd folder in MQRFH2 NameValueLength length The length, in bytes, of the data in the NameValueData field, that is, the length of mcd folder content.
NameValueData 
<mcd>
  <Msd>xml</Msd>
  <Set>value</Set>
  <Type>value</Type>
  <Fmt>value</Fmt>
</mcd>
 The message content descriptor. For more information, see IBM Documentation for Message Broker.
ComIbmDni folder in MQRFH2 NameValueLength length The length, in bytes, of the ComIbmDni folder.
NameValueData 
<ComIbmDni>
  :
</ComIbmDni>
 The ComIbmDni folder (see ComIbmDni folders).