You are here: Part 3: Advanced Concepts > Configuring QoS with XML > URL Groups

URL Groups

To provide redundancy and fault tolerance, you can specify multiple locations for a single XML document via URL groups. The syntax of a URL group is:

[URL1 | URL2 | URL2 | ... | URLn]

For example:

[file:///usr/local/default_dds.xml | file:///usr/local/alternative_default_dds.xml]

Only one of the elements in the group will be loaded by Connext DDS, starting from the left.

Brackets are not required for groups with a single URL.

The NDDS_QOS_PROFILES environment variable contains a set of URL groups separated by semicolons. For example, on Linux and Solaris systems (note: this should be entered in a single command line):

   [str://"<dds><qos_library name="MyQosLibrary"></qos_library></dds>"]

The url_profile field in the PROFILE QosPolicy (DDS Extension) will contain a sequence of URL groups.

© 2016 RTI