WebSphere Message Brokers
File: ac04810_
Writer: Terry Cowling

Reference topic

This build: July 31, 2007 21:17:40

ResetContentDescriptor node

This topic contains the following sections:

Purpose

Use the ResetContentDescriptor node to request that the message is re-parsed by a different parser. If the new parser is MRM, you can also specify a different message template (message set, type, and format). This node does not re-parse the message, but the properties that you set for this node determine how the message is parsed when it is next re-parsed by the message flow.

The node associates the new parser information with the input message bit stream. If the message has been parsed already to create a message tree, and the contents of the tree have been modified (for example, by a Compute node), the ResetContentDescriptor node must invoke the current parser that is associated with the message to parse the message and re-create the bit stream.

If your message flow has updated the message before it is received by the ResetContentDescriptor node, ensure that the changed message contents are still valid for the current parser. If the contents are not valid, the parser generates an error when it attempts to re-create the bit stream from the message tree, and the ResetContentDescriptor node raises an exception. For example, if you have added a new field to a message in the MRM domain, and the field is not present in the model, the re-creation of the bit stream fails.

The ResetContentDescriptor node does not:

  • Change the message content; it changes message properties to specify the way in which the bit stream is parsed next time that the parser is invoked.
  • Convert the message from one format to another; for example, if the incoming message has a Message Format of XML and the outgoing Message Format is CWF, the ResetContentDescriptor node does not do any reformatting. It invokes the parser to re-create the bit stream of the incoming XML message, which retains the XML tags in the message. When the message is re-parsed by a subsequent node, the XML tags are invalid and the re-parse fails.

The ResetContentDescriptor node is represented in the workbench by the following icon:

ResetContentDescriptor node icon

Using this node in a message flow

For an example of how to use this node, assume that you want to swap between the BLOB and the MRM domains. The format of an incoming message might be unknown when it enters a message flow, so the BLOB parser is invoked. Later on in the message flow, you might decide that the message is predefined as a message in the MRM domain, and you can use the ResetContentDescriptor node to set the correct values to use when the message is parsed by a subsequent node in the message flow.

The following table shows typical ResetContentDescriptor node properties.
Property Value
Message Domain MRM
Reset Message Domain Selected
Message Set DH53CU406U001
Reset Message Set Selected
Message Type m_MESSAGE1
Reset Message Type Selected
Message Format CWF
Reset Message Format Selected

The Message Domain is set to MRM, and the MRM parser is invoked when the message is next parsed. The message set, type, and format are the message template values that define the message model, and all the reset check boxes are selected because all the properties need to change.

The ResetContentDescriptor node causes the BLOB parser that is associated with the input message to construct the physical bit stream of the message (not the logical tree representation of it), which is later passed to the MRM parser. The MRM parser then parses the bit stream using the message template (Message Set, Message Type, and Message Format) specified in this ResetContentDescriptor node.

Start of changeAt Version 6.1, it is no longer necessary to include a ResetContentDescriptor node after an XSLTransform node in your message flow to set message domain, message set, message type, and message format of the message generated by the XSLTransform node. The XSLTransform node has the capability to perform this function.End of change

Configuring the ResetContentDescriptor node

When you have put an instance of the ResetContentDescriptor node into a message flow, you can configure it. To display its properties, either double-click the node, or right-click the node and click Properties.

All mandatory properties for which you must enter a value (those that do not have a default value defined) are marked with an asterisk.

Configure the ResetContentDescriptor node as follows:

  1. Optional: On the Description tab, enter a short description, a long description, or both. You can also rename the node on this tab.
  2. On the Basic tab:
    1. To use a different parser associated with the message, specify the new domain In Message Domain:
      • MRM
      • XMLNSC
      • XMLNS
      • JMSMap
      • JMSStream
      • MIME
      • BLOB
      • IDOC
      • XML

      You can also specify a user-defined parser if appropriate.

      Select the Reset Message Domain check box.

    2. If the MRM parser is to re-parse the message, specify the other properties of the model that are to be associated with the input message, and select the Reset check box beneath each field. If the MRM parser is associated with the input message already, you need to specify only the properties that are to change.
      1. Enter the message set in Message Set. Choose a value from the drop-down list of available message sets (the name and identifier of the message set are shown).
      2. Enter the identifier of the message in Message Type. You can find this identifier in the properties of the message in the editor view. You specified the message identifier when you created the message. Enter the identifier exactly as shown in the message properties.
      3. Enter the format of the message in Message Format. This property specifies the wire format for the MRM parser. You can select one of the formats from the drop-down list (which lists the identifiers of those formats that you have defined on the message set specified above).

      These properties set the domain, set, type, and format that you want in the message header of the message that you want to pass through the ResetContentDescriptor node. However, these actions are taken only if suitable headers already exist. If the message does not have an MQRFH2 header, the node does not create one.

      Leave Message Set, Message Type, and Message Format blank if you have specified the XML, JMS, MIME, or BLOB parser.

  3. On the Validation tab, set the validation properties if you want the MRM parser to validate the body of messages against the dictionary generated from the message set. (If a message is propagated to the Failure terminal of the node, it is not validated.)

    For more details, refer to Validating messages and Validation properties.

Terminals and properties

The ResetContentDescriptor node terminals are described in the following table.

Terminal Description
In The input terminal that accepts a message for processing by the node.
Failure The output terminal to which the message is routed if an error is detected by the node.
Out The output terminal to which the message is routed if a new parser is identified by the properties.

The following tables describe the node properties. The column headed M indicates whether the property is mandatory (marked with an asterisk if you must enter a value when no default is defined); the column headed C indicates whether the property is configurable (you can change the value when you add the message flow to the bar file to deploy it).

The ResetContentDescriptor node Description properties are described in the following table.

Property M C Default Description
Node name No No The node type The name of the node.
Short Description No No   A brief description of the node.
Long Description No No   Text that describes the purpose of the node in the message flow.

The ResetContentDescriptor node Basic properties are described in the following table.

Property M C Default Description
Message Domain No No   The message domain that is associated with the message that you want to re-parse.
Reset Message Domain Yes No Cleared If you select the check box, the message domain is reset.
Message Set No No   The message set that is associated with the message that you want to re-parse.
Reset Message Set Yes No Cleared If you select the check box, the message set is reset.
Message Type No No   The message type that is associated with the message that you want to re-parse.
Reset Message Type Yes No Cleared If you select the check box, the message type is reset.
Message Format No No   The message format that is associated with the message that you want to re-arse.
Reset Message Format Yes No Cleared If you select the check box, the message format is reset.

The ResetContentDescriptor node Parser Options are described in the following table.

Property M C Default Description
Parse timing Yes No On Demand This property controls when an input message is parsed. Valid values are On Demand, Immediate, and Complete.

Refer to Parsing on demand for a full description of this property.

Use MQRFH2C compact parser for MQRFH2 header No No Cleared This property controls whether the MQRFH2C compact parser, instead of the MQRFH2 parser, is used for MQRFH2 headers.
Use XMLNSC Compact Parser for XMLNS Domain Yes No Cleared This property controls whether the XMLNSC Compact Parser is used for messages in the XMLNS Domain. If you set this property, the message data appears under XMLNSC in nodes that are connected to the output terminal when the input RFH2 header or Domain is XMLNS.
Retain Mixed Content Yes No Cleared This property controls whether the XMLNSC parser creates elements in the message tree when it encounters mixed text in an input message. If you select the check box, elements are created for mixed text. If you clear the check box, mixed text is ignored and no elements are created.
Retain Comments Yes No Cleared This property controls whether the XMLNSC parser creates elements in the message tree when it encounters comments in an input message. If you select the check box, elements are created for comments. If you clear the check box, comments are ignored and no elements are created.
Retain Processing Instructions Yes No Cleared This property controls whether the XMLNSC parser creates elements in the message tree when it encounters processing instructions in an input message. If you select the check box, elements are created for processing instructions. If you clear the check box, processing instructions are ignored and no elements are created.

The ResetContentDescriptor node Validation properties are described in the following table. Refer to Validation properties for a full description of these properties.

Property M C Default Description
Validate Yes Yes None This property controls whether validation takes place. Valid values are None, Content, Content and Value, and Inherit.
Failure Action Yes No Exception This property controls what happens if validation fails. You can set this property only if you set Validate to Content and Value or Content. Valid values are User Trace, Local Error Log, Exception, and Exception List.
Include All Value Constraints Yes No Selected You cannot edit this property. If you select this check box, basic value constraint checks are included in Content and Value validation.
Fix Yes No None You cannot edit this property. Valid values are None, and Full.
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This build: July 31, 2007 21:17:40

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