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| properties tree |
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| selfown |
 Posted: Thu Feb 17, 2005 1:51 am Post subject: properties tree |
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Apprentice
Joined: 07 Jan 2005
Posts: 39
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Hi,
Can anyone please tell me the use of properties tree.
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| Heidi-Lize |
| Posted: Thu Feb 17, 2005 2:48 am Post subject: |
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Newbie
Joined: 20 Jan 2005
Posts: 6
Location: South Africa
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Extract from the WBI help file. I suggest you try reading that and the redbooks that you can download from IBM's website for more info.
Properties tree
The properties tree is the first element of the message tree and holds information about the characteristics of the message.
The root of the properties tree is called Properties. It is the first element under Root. All message trees generated by the built-in parsers include a properties tree for the message. If you create your own user-defined parser, you can choose whether the parser creates a properties tree. However, for consistency, you are recommended to include this action in the user-defined parser.
The properties tree is created and inserted in the tree following all the headers but preceding the message data. It contains a set of standard properties that you can manipulate in the message flow nodes in the same way as any other property. The majority of these fields map to fields in the supported WebSphere MQ headers, if present, and are passed to the appropriate parser when a message is delivered from one node to another.
For example, the MQRFH2 header contains information about the message set, type, and format. These values are stored in the properties tree as MessageSet, MessageType, and MessageFormat. To access these values using ESQL within the message processing nodes, refer to these values in the Properties tree; do not refer directly to the fields in the headers from which they are derived.
If the message is converted to a bit stream, for example in an output node, any properties remaining solely in the properties tree (that is, not in any header in the output messages) are not included in any part of the output message.
The Properties parser ensures that the values in the header fields match the values in the properties tree on input to, and output from, every node. On exit from a node, the Properties parser invokes each header parser with the values that it currently contains. It then requests values back from the header parser and updates its own values. If you have coded ESQL in the node that updates values either in the properties tree, or in the header, or both, these values always match when the tree is passed on from that node. However, if you have updated a field in both the properties tree and the header with different values, the value that you set in the header is overwritten by the value that you set in the properties tree.
When the message flow processing is complete, the properties tree is discarded.
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