Queuing Service makes use of XSD files to validate the XML configuration files used to configure Queuing Service. Due to the restrictions imposed by XSD schemas for XML 1.0, some of the tags used in the configuration must be grouped in order. This behavior is intended; Queuing Service validates the XML files before parsing them to catch as many parsing errors as possible beforehand.

3.2 XML Syntax and Validation

The XML configuration file must follow these syntax rules:

  • The syntax is XML; the character encoding is UTF-8.
  • Opening tags are enclosed in <>; closing tags are enclosed in </>.
  • A tag value is a UTF-8 encoded string. Legal values are alphanumeric characters. Queuing Service's parser will remove all leading and trailing spaces from the string before it is processed. For example, " <tag> value </tag>" is the same as "<tag>value</tag>".
  • All values are case-sensitive unless otherwise stated.
  • Comments are enclosed as follows: <!-- comment -->.
  • The root tag of the configuration file must be <dds> and end with </dds>.

Queuing Service provides an XSD file that describes the format of the XML content. We recommend including a reference to this file in the XML file that contains the Queuing Service configuration—this provides helpful features in code editors such as Visual Studio and Eclipse, including validation and auto-completion while you are editing the XML file.

The XSD definition of the XML elements is in <NDDSHOME>/resource/schema/rti_queuing_service.xsd.

To include a reference to the XSD document in your XML file, use the attribute xsi:noNamespaceSchemaLocation in the <dds> tag. For example:

<?xml version="1.0" encoding="UTF-8"?>
<dds xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation= "<Queuing Service installation directory>/resource/schema/rti_queuing_service.xsd">
... 
</dds>