XPath

XPath is a language for navigating through elements and attributes and for finding information in XML documents. XPath is a major element in the W3C's XSLT standard - (XQuery and XPointer are both built on XPath expressions).

In StoryTeller, the libxml2 open source library is used for parsing the message data.

With XPath, you select a node using a path. The path can be absolute or relative.

The root node in StreamServe messages is /data/message. StreamServe variables are accessed via $<variable_name> only.

(Deprecated variable reference: /data/variables/<variable_name>)

XPath expressions

In addition to defining simple location paths to fields, such as: /data/message/field1, XPath can also be used to define rather complex expressions to retrieve values depending on certain conditions. For example, if you want a value to be rendered in red if the value is negative.

Note:

Only use the Data Selection dialog to browse for fields and variables in the Message. To manually enter XPath expressions, enter them directly in the Properties panel, either in property fields or in the Modification field.

For more information on XPath and how to create XPath expressions, see the XMLIN documentation and e.g.:

http://www.w3.org/TR/xpath

http://www.w3.org/Style/XSL/