When Internet access is not available or the Internet connection is slow the OASIS XML catalogs present in the list maintained in the XML Catalog Preferences panel will be scanned trying to map a remote system ID (at document validation) or a URI reference (at document transformation) pointing to a resource on a remote Web server to a local copy of the same resource. If a match is found then <oXygen/> will use the local copy of the resource instead of the remote one. This enables the XML author to work on his XML project without Internet access or when the connection is slow and waiting until the remote resource is accessed and fetched becomes unacceptable. Also XML catalogs make documents machine independent so that they can be shared by many developers by modifying only the XML catalog mappings related to the shared documents.
<oXygen/> supports any XML catalog file that conforms to one of:
the OASIS Technical Resolution 9401:1997 including the plain-text flavor described in that resolution
The version 1.1 of the OASIS XML Catalog specification introduces the possibility to map a system ID, a public ID or a URI to a local copy using only a suffix of the ID or URI used in the actual document. This is done using the new catalog elements systemSuffix and uriSuffix .
An XML catalog can be used also to map a W3C XML Schema specified with an URN in the xsi:schemaLocation attribute of an XML document to a local copy of the schema. For example if the XML document specifies the schema with:
<topic xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:oasis:names:tc:dita:xsd:topic.xsd:1.1">
the URN can be resolved to a local schema file with a catalog entry like:
<system systemId="urn:oasis:names:tc:dita:xsd:topic.xsd:1.1" uri="topic.xsd"/>
An XML Catalog file can be created quickly in <oXygen/> starting from the two XML Catalog document templates called OASIS XML Catalog 1.0 and OASIS XML Catalog 1.1 and available in the document templates dialog.
User preferences related to XML Catalogs can be configured from → +XML / XML Catalog