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Configuring Oxygen to Validate from Catalog-referenced DTDs


Users of the Oxygen XML editor.


To enable Oxygen to validate documents whose DTDs are referenced in catalog files.


  • Installed Oxygen XML Editor, either as standalone application or Eclipse plugin.

Configuring Oxygen to Validate from Catalog-referenced DTDs

The Oxygen XML editor, whether used in the Eclipse IDE or in standalone mode, can be configured to locate DTDs from a catalog file rather than from direct references to the DTD on your filesystem or on the internet via a URL.

The example used in this HowTo document refers to catalog files for Forrest; on the Forrest site you can find some background information on Forrest-specific usage of catalog fles. A more general article on catalogs can be found on the Apache XML-Commons site.

Configuring Oxygen to use Catalog files from within Eclipse

Before you begin these steps, be sure you know where on your filesystem the catalog files that contain references of interest are located. Example: know where Forrest is installed on your system (UC Berkeley developers are able to check out Forrest from code repositories on and - coming soon -

  • In Eclipse, navigate to the Preferences dialog (Window:Preferences)
  • In the Preferences dialog, navigate to Oxygen's XML Catalog settings pane (Oxygen : XML : XML Catalog)
  • Add references to the XML Catalogs you wish to add. For example, if Forrest is installed in C:\workspace\apache-forrest-0.7, the reference to Forrest's main catalog would be
  • Close and restart Eclipse.

Configuring standalone Oxygen to use Catalog files

Open Oxygen, navigate to Tools : External Tools : Preferences and open the preferences tree to XML : XML Catalog (make sure that there's no text in the search-filter text box at the top of the tree). Add references to the XML Catalogs you wish to add as described in the section on configuring Oxygen from within Eclipse, above.