Multipart messages

A multipart message contains one or more other messages within its structure. The contained message is sometimes referred to as an embedded message .

A multipart message must contain a group, or a complex type, with its Composition property set to Message. This group or complex type can contain a list of references to messages that are allowed to appear at that location in the message structure, or it might be empty, allowing any message to appear. When a message is parsed, only one message can appear in that position as an embedded message.

Message envelopes

A common use of multipart messages is to define an outer message with a fixed structure. This outer message is called the message envelope. Within the message envelope a group or complex type is included, as described above. Examples of message standards that can be modeled using this technique are Start of changeEDIFACT, X12, SWIFT, SOAP XML, SAP ALE IDoc, multipart MIME, and RosettaNetEnd of change.

Identifying the embedded message

When a multipart message is parsed, the parser must be able to identify the embedded message; it might be any of the messages that are referenced by the group or complex type, or it might be a message that is not referenced by the group or complex type, perhaps from a different message set. This is achieved using one of Start of changefour techniques, Automatic, Message Identity, Message Path, or ManualEnd of change.

Automatic
Start of changeUsed when parsing XML messages, such as SOAP. The parser automatically identifies and parsesEnd of change embedded messages using the tag in the XML document.
Message Identity
Start of changeUsed by the MRM parser.End of change See Identifying an embedded message using a Message Identity.
Message Path
Start of changeUsed by the MRM parser.End of change See Identifying an embedded message using a Message Path.
Start of changeManualEnd of change
Start of changeUsed by the MIME parser. The parser treats embedded messages as BLOBs. If you want to parse the BLOB using another parser, you must do so manually using ESQL, or Java, or a ResetContentDescriptor node.End of change

Restrictions

Start of changeUnless using the Manual identification technique,End of change all embedded messages must be of the same physical format as the outermost message, and have the same character set and encoding.

Start of changeWhen using the Automatic or Message Path identification techniques, all embedded messages must be from the same message set as the multipart message.End of change

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Copyright IBM Corporation 1999, 2009Copyright IBM Corporation 1999, 2009.
Last updated : 2009-01-07 15:20:46

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