While working on the integration of the DATEX II data model as an option into the OTS 2 (http://www.opentrafficsystems.org) protocol and while clarifying the requirements for using this in the German project simTD (http://www.simtd.de) the need for a catalogue extension was identified.

The catalogue allows a server to specify which kind of elaborated or situation data it has to offer. Furthermore locations can be specified for which the data is available (optionally).

Catalogues are modeled as identifiable objects and contain CatalogueItems which can be referenced by an index number. Catalogues can be published in CataloguePublications.

Using the OTS 2 protocol a client is able to ask the server for a CataloguePublication and then place subscriptions referencing to the Catalogue(s) and CatalogueItem(s). This way the client can choose between different data publications a server has to offer and the server only needs to publish the data someone has ordered.

The extension proposal can be found in the deployments extensions section on this website (http://www.datex2.eu/content/catalogue-extension).