Part I. Overview

Tracker is a central repository of user information, that provides two big benefits for the desktop: Share data between applications (it doesn't matter the source once it is stored in the repository) and Link information from different sources (mixing contacts with files, location, activities and whatnot).

This central repository can work only with a very well defined data model, that applications can rely to store and recover their information. That data model is defined using a semantic web artifact called ontology. An ontology defines the concepts (classes) and properties (attributes) that the items in the repository can be/have.

There is an EU-funded project called Nepomuk, where a core of ontologies to model the Desktop were defined. This set was a very good starting point for Tracker but new requirements and heavy development in collaboration with applications provided a very valuable feedback, in form of fixes and extensions. Some of this work is already submitted for approval in the upstream version, but the process is long and hard, so the Tracker ontologies are diverging slowly.

This documentation describes the Tracker flavour of Nepomuk ontologies. The big picture and basic concepts are the same as in the original Nepomuk, but "hell and heaven are in the details". All classes, properties and restrictions included in these pages should work in Tracker. Any error in this documentation can be reported in the Tracker Mailing list or bugzilla.

This is just documentation about the ontologies. For more information about Tracker technical details and implementation, please refer to the Tracker Documentation wiki page in GNOME.

Table of Contents

XML schema (XSD): Basic types definitions (int, double,...)
Overview
XSD Ontology Classes
XSD Ontology Properties
Resource Description Framework (RDF): Core RDF classes to keep the internal consistency of the ontology
RDF Ontology Classes
RDF Ontology Properties
Dublin Core metadata (DC): Common superproperties for documents
DC Ontology Classes
DC Ontology Properties
Nepomuk Information Element (NIE): Top classes in the ontology. Almost everything else is subclass of these.
Overview
NIE Ontology Classes
NIE Ontology Properties
Nepomuk Annotation Ontology (NAO): Tags, ratings and other common annotations to all classes
NAO Ontology Classes
NAO Ontology Properties
Nepomuk File Ontology (NFO): About files and other desktop resources.
NFO Ontology Classes
NFO Ontology Properties
Nepomuk Contacts Ontology (NCO): All about contacts. Rough equivalent of the VCARD standard.
Overview
NCO Ontology Classes
NCO Ontology Properties
Nepomuk Messaging Ontology (NMO): Model for messages and communications, including Email, SMS, MMS and phone calls
Overview
NMO Ontology Classes
NMO Ontology Properties
Nepomuk Calendar Ontology (NCAL): Automatic translation of the ICAL standard into ontology. Too complex for our taste. Please check SCAL
NCAL Ontology Classes
NCAL Ontology Properties
Simplified Calendar Ontology (SCAL): Simple and efficient ontology to represent calendar information (events, ToDos, recurrency rules...)
SCAL Ontology Classes
SCAL Ontology Properties
Nepomuk MultiMedia (NMM): Description of multimedia objects like Music, Video and Images
Overview
NMM Ontology Classes
NMM Ontology Properties
Maemo Transfer Ontology (MTO): Representation of download and upload operations in the system
MTO Ontology Classes
MTO Ontology Properties
Maemo Feeds Ontology (MFO): Model for feeds and alike online streams
Overview
MFO Ontology Classes
MFO Ontology Properties
Multimetida Transfer Protocol (MTP) Ontology: Extra properties to add MTP information to the objects in the ontology
MTP Ontology Classes
MTP Ontology Properties
Simplified Maemo Location Ontology (SLO) (experimental/for testing): Simpler, faster, better ontology for locations and landmarks
SLO Ontology Classes
SLO Ontology Properties
Tracker-specific annotations Ontology: Internal tracker properties
TRACKER Ontology Classes
TRACKER Ontology Properties
Maemo-specific classes: Some maemo/meego specific properties
MAEMO Ontology Classes
MAEMO Ontology Properties
Full-text indexed properties in the ontology