You can access an attribute or element in two different ways within Biztalk using ‘Distinguished Fields’ and ‘Promoted Properties’. A basic rule for ‘which to use’ would be: Always use a Distinguished Field, unless you need to route, track, or correlate on the content, then use promoted fields.
Promoted Properties
Promoted properties are message context properties that are used by the BizTalk Messaging Engine for purposes of document routing, for message tracking, and for evaluation in Orchestrations. You can explicitly elevate a field in a document to the message context as a Property field by editing the schema for the document in the BizTalk Server Schema Editor that is available in Visual Studio. In order to write a field in a document to the message context as a property field, the document schema must have an associated property schema. Property fields are limited to 255 characters. The IsPromoted property of Property fields in the message context is set to True.
Distinguished Fields
Distinguished fields are message context properties that do not require a separate property schema and that are only accessible from Orchestrations. Distinguished fields cannot be used for routing or tracking. Since Distinguished fields do not require a separate property schema, the evaluation of Distinguished fields by the Orchestration engine consumes less overhead than the evaluation of Property fields by the Orchestration engine. The evaluation of Property fields requires an XPath query, the evaluation of Distinguished fields does not require an XPath query as the pipeline disassembler populates the Distinguished fields in the context and the orchestration engine reads the cached values. However, if the orchestration engine does not find the property in the context, it will then initiate an XPath query to find the value. Distinguished fields do not have a size limitation. The IsPromoted property of Distinguished fields in the Message context is set to False.
