1. Developing SOA Applications with Oracle SOA Suite
  2. Sharing Functionality Across Service Components
  3. Creating Transformations with the XQuery Mapper
  4. Introduction to the XQuery Mapper
  5. About the Source and Target Trees

About the Source and Target Trees

The left pane of the XQuery Mapper shows the source tree, and the right pane shows the target tree. Tree nodes can be XML elements, attributes, and some other XQuery constructs.

XML elements are identified by the <> icon. Attributes use a different icon, and attribute names are prefixed with the @ symbol, as they appear in an XPath expression. The element or attribute multiplicity is shown using the following standard suffixes:

  • ?: Zero or one occurrence of an element/attribute.

  • +: One or more occurrences of an element/attribute.

  • *: Zero or more occurrences of an element/attribute.

The source tree shows the input sources or parameters for the selected XQuery function. The root level elements represent the input parameters for the function. If a root node is a complex element, then its child elements and attributes appear under the root node.

The target tree can include XML elements, attributes, and some programming control structures. The elements and attributes can appear in the following forms:

  • Grayed Font: An element that is part of the target schema, but not defined yet. Once you map a grayed element to a source element, it appears in normal font.

  • Normal Font: An element that either corresponds to an element constructor in the source, or copied implicitly from the source data.

  • Underlined Font: An element that is incompatible with the specified target schema. This element may appear because of an incorrect element name used in an element constructor, or because of a sequence assignment with an incorrect schema type.

The target tree can also contain programming control structures like If-Then-Else, Union operator, and comma operator:

  • If-Then-Else Operator: The If-Then-Else operator shows up as a node called Conditional. The Conditional node has nested branches for If Then and Else. You can choose the Make Conditional option from the context menu of a node to make it conditional.

  • Union Operator (and other sequence combining operators): These cannot be created in the graphical view of the XQuery Mapper. However, if the source view contains such an operator, it is represented in the target tree with a node called All, and the operands are represented as subnodes of the all node.

  • Comma Operator: The comma operator shows up as a node called List. The subnodes represent the comma-limited operands of the comma operator. You can choose the Clone option from the context menu of target tree node to apply a comma operator.