XML Schema (MS XDR Biztalk)
BizTalk uses XML to describe schemas using a notation convention called XML Data, subset reduced. The abbreviated term, XDR, stands for the schema format that most recent Microsoft XML schema parsers understand. The advantage of using XML to describe a schema, such as XDR conventions dictate, is that users can use their XML skills to describe the schema.
Other advantages that XDR brings over other forms of contract description that can be found in use (such as DTD). Schemas allow you to describe the name of the tags and the order of the tags. You can also specify that the content of one element is a string of characters, and that another element is actually a number.
To set the XDR Schema for source or target files
1. In the map window, click the down arrow to the right of the Source or Target Structured Schema box and select XDR (XML Data Reduced) as the External Type.
2. Navigate to the schema file you want to use.
3. After you have connected to the file, two radio button choices appear: Replace Existing Layout(s), Append to Existing Layout(s). Click OK to save your selections.
Element and Attribute
XML documents consist of elements and attributes. If the field is an attribute, the DefaultExpression contains the attribute type (attribute field name). However, the Default Expression of element field is empty.
Attribute of an Element
An element type may contain attributes. In this case, the attribute field is named as element field name (element type)_attribute field name (attribute type). Because one element field may have the same name as the other has in the same record, a naming conflict is avoided.