PrF UG files rdf support

RDF(S) Support in

Protege-Frames User's Guide
Project Types
Understanding Project Types
Protege Files
Protege DB Format
Experimental XML Format
Protege-OWL
RDF(S) Support in Protege
Using the RDF Backend
Exporting a Project to CLIPS
Exporting a Project to HTML
Glossary, Editing Help

Protege allows you to create and edit Resource Description Framework (RDF) schema and instance data. (For more information about RDF, see http://www.w3.org/RDF.) Protege provides the following types of RDF (Schema) support:

• Protege-OWL (recommended)

• an RDF backend for Protege-Frames

• additional RDF(S) plug-ins for Protege-Frames, including Sesame and Joseki support

Protege-OWL and RDF(S)

OWL is an extension of RDF, so any RDF project can also be regarded as an OWL project which simply does not use the advanced OWL features. Although the focus of the OWL Plugin is on OWL ontologies, it can also be used to edit RDF ontologies and RDF Schema files or databases. However, we don't recommend mixing pure RDF(S) elements with OWL elements in OWL ontologies.

The following steps show how to:

• import or create a file in RDF(S) format using Protege-OWL

• add RDF(S) support to an existing OWL project

These steps address the file format only; for additional information, see the Protege-OWL resources page.

Please note the following limitations:

• Although you may see the full OWL interface when editing an RDF(S) project, it is your responsibility to avoid using OWL-specific elements in your project.

• Currently, when you go to import (open from an existing) RDF(S) file, there is no separate RDF format option. You need to select OWL Files (.owl or .rdf) and later select RDF Schema or Pure RDF Schema without OWL.

• When you save your RDF(S) project, the interface currently does not save separate RDFS and RDF files; instead, it combines everything in a single file that is given a .owl extension. This may be fixed in future versions.

Note that the use of RDF in Protege-OWL is not necessarily compatible with the RDF Backend for Protege-Frames, which was initially developed prior to the existence of OWL. Overall, the RDF support in Protege-OWL provides cleaner semantics and a richer set of modeling elements.

Importing or Creating an RDF(S) Project with Protege-OWL

1. Create a new project, either by selecting Create New Project from the start-up dialog or File | Create New in the Protege window.

2. Select OWL Files (.owl or .rdf) as the Project Type.

   

   Create New Project dialog, "OWL Files ..." selected

3. If you are importing an existing file, make sure to check Create from Existing Sources, located at the top of the dialog box. If you are creating a new RDF file, leave it unchecked (default).

   

   Create from Existing Sources checkbox (checked)

4. Click Next.

5. Specify any common ontologies to use and click Next.

6. Specify your default RDF namespace and click Next.

7. You can now choose your language profile. For an RDF project, select RDF Schema or Pure RDF Schema without OWL.

   

   Create New Project dialog, "Pure RDF ..." selected

Activating RDF(S) Support in an OWL Project

To activate RDF(S) support in an existing Protege-OWL project:

1. Select the OWL | Preferences menu option.

2. In the OWL Preferences dialog, activate an RDF profile by changing the Language Profile to RDF Schema or Pure RDF Schema without OWL.

   

   OWL Preferences dialog, General tab, "Pure RDF ..." selected

3. Click Close.

4. The Protege-OWL window will display buttons to create pure RDFS classes and RDF properties. In particular:

• If you chose RDF Schema, there will be an additional button on the Properties tab, which can be used to create RDF properties:

  

  Property tab with extra buttons

  You can also decide whether new classes shall be RDFS classes or OWL classes using "Create class using metaclass", or you can make rdfs:Class the default metaclass (both with a right-click on the classes tree in the OWLClasses tab).

• If you chose Pure RDF Schema without OWL, the buttons on the Properties tab will be restricted to RDF properties:

  

  Property tab

RDF Backend for Protege-Frames

You can use Protege-Frames to design RDF schema and create the corresponding instance data. You can also view and edit your existing RDF files in Protege-Frames. The RDF backend for Protege-Frames was developed prior to the development of the Protege OWL interface and is not necessarily compatible with Protege-OWL. With the advent of Protege-OWL, it is no longer under active development, but some support is still available.

• Instructions on creating or converting a file using the RDF backend

Note: This backend is actually an RDFS/RDF backend which saves a schema file (RDFS) and an instance file (RDF).

This interface has a number of limitations:

• The backend uses the standard Protege-Frames GUI, which is not RDF(S) -specific. It is not clear how you can enter RDF specific elements. You see exactly the same GUI as for "normal" Protege-Frames.

• Only the RDF Schema namespace (http://www.w3.org/TR/1999/PR-rdf-schema-19990303) is supported when saving (on import, the new namespace is also recognized).

• Namespace abbreviations cannot be edited (they are automatically generated).

• rdfs:seeAlso, rdfs:isDefinedBy, rdfs:label, container, and reified statements are not supported.

• Multiple types for a single resource were not supported, prior to the 3.3 release.

• You cannot make changes to the standard meta classes. (i.e., rdf:Resource, rdf:Property, rdfs:Class, etc.)

• XML Schema data types are not recognized as rdfs:Literal (but it is unclear that they should be).

Additional RDF Plug-ins

The Protege community has written additional RDF plug-ins to support other RDF frameworks:

• Protege RDF(s)-DB Backend Plugin: Store/retrieve RDFS ontologies in the Sesame RDF framework.

• Protege2Joseki: Import/export Protege ontologies from/to Joseki RDF Server.