Selecting XPath or XQuery for Expression Building

ActiveVOS Designer User’s Guide

You can select an expression language to build copy operations in an assign activity and to map data in invoke, reply and people activities.

The default language is XPath, which is supported by the WS-BPEL 2.0 specification. ActiveVOS provides an extension for XQuery.

The following table provides a brief comparison between XPath and XQuery as used in BPEL data mapping:

XPath	XQuery
Recommended if portability is an issue. Language is supported by WS-BPEL 2.0	ActiveVOS extension for BPEL
May be more suitable for multiple-part message variables	Builds large documents easily from a single-part variable
Limited to expression evaluation of one document node at a time	Allows manipulation of data from an entire XML document
Good choice if you prefer to use multiple copy operations in an assign activity or data mapping table in reply, invoke, or people activity	Better at date handling, with many date functions
Location path expressions resolve to a string	Queries generate an XML result
	Similar to a SQL-like query language. Easier to iterate over repeating elements with "FLWOR expressions" (FOR, LET, WHERE, ORDER BY, and RETURN) for performing joins