# Nepomuk Information Element (NIE): Top classes in the ontology. Almost everything else is subclass of these.

Authors:
  - Ludger van Elst, DFKI, <elst@dfki.uni-kl.de>
  - Michael Sintek, DFKI, <michael.sintek@dfki.de>
  - Leo Sauermann, DFKI, <leo.sauermann@dfki.de>
  - Antoni Mylka, DFKI, <antoni.mylka@dfki.de>
Editors:
  - Antoni Mylka, DFKI, <antoni.mylka@dfki.de>
Contributors:
  - Christiaan Fluit, Aduna, <christiaan.fluit@aduna-software.com>
  - Evgeny 'phreedom' Egorochkin, KDE Strigi Developer, <stexx@mail.ru>
Upstream:

  Upstream version

ChangeLog:

  Tracker changes

Copyright:

  © 2007 DFKI © 2009 Nokia. The ontologies are made available under the terms of NEPOMUK software license (FIXME verify)

## Overview

### Introduction

The core of the NEPOMUK Information Element Ontology and the entire Ontology Framework revolves around the concepts of DataObject and InformationElement. They express the representation and content of a piece of data. Their specialized subclasses (defined in the other ontologies) can be used to classify a wide array of desktop resources and express them in RDF.

nie:DataObject class represents a bunch of bytes somwhere (local or remote), the physical entity that contain data. The meaning (intepretation) of that entity, the information for the user contained in those bytes (e.g. a music file, a picture) is represented on the nie:InformationElement side of the ontology.

Both sides are linked using the property nie:interpretedAs (and its reverse nie:isStoredAs), indicating the correspondence between the physical element and its interpretation. There is also a property to link nie:InformationElements, representing the logical containment between them (like a picture and its album).

#### Common properties

Given that the classes defined in this ontology are the superclasses for almost everything in the Nepomuk set of ontologies, the properties defined here will be inherited for a lot of classes. It is worth to comment few of them with special relevance:

nie:title

  Title or name or short text describing the item

nie:description

  More verbose comment about the element

nie:language

  To specify the language of the item.

nie:plainTextContent

  Just the raw content of the file, if it makes sense as text.

nie:generator

  Software/Agent that set/produced the information.

nie:usageCounter

  Count number of accesses to the information. It can be an indicator of relevance for advanced searches

#### Dates and timestamps representations

There are few important dates for the life-cycle of a resource. These dates are properties of the nie:InformationElement class, and inherited for its subclasses:

nie:informationElementDate

  This is an ''abstract'' property that act as superproperty of the other dates. Don't use it directly.

nie:contentLastModified

  Modification time of a resource. Usually the mtime of a local file, or information from the server for online resources.

nie:contentCreated

  Creation time of the content. If the contents is created by an application, the same application should set the value of this property. Note that this property can be undefined for resources in the filesystem because the creation time is not available in the most common filesystem formats.

nie:contentAccessed

  For resources coming from the filesystem, this is the usual access time to the file. For other kind of resources (online or virtual), the application accessing it should update its value.

nie:lastRefreshed

  .

### URIs and full representation of a file

One of the most common resources in a desktop is a file. Given the split between Data Objects and Information Elements, some times it is not clear how a real file is represented into Nepomuk. Here are some indications:

1. Every file (local or remote) should generate one DataObject instance and an InformationElement instance.
2. Even when Data Objects and Information Elements are completely different things, for efficency reasons in Tracker we use the same URI for both of them.
3. The URI will be an autogenerated ID, and the real location of the item (e.g. ''file://path/to/file.mp3'') is a property of the Data Object
4. Every DataObject must have the property nie:url, that points to the location of the resource, and should be used by any program that wants to access it.
5. There is a deprecated property in the ontology: nie:isStoredAs . We discourage its use in the code: in the best case it is a loopback to the nie:url value, but in general it can contain any value or not be set at all.

Here comes an example, for the image file /home/user/a.jpeg:

    <urn:uuid:10293801928301293> a nmm:Photo, nfo:FileDataObject ;
    	# Properties as nmm:Photo
    	 nfo:width 49 ;
    	 nfo:height 36 ;
    	nmm:flash <nmm:flash-off>;
    	nmm:whiteBalance <nmm:white-balance-automatic> ;
    	nfo:equipment [ a nfo:Equipment ; nfo:make 'Nokia'; nfo:model 'N900'; nfo:equipmentSoftware 'Tracknon' ] ;

    	# Properties from nfo:FileDataObject
    	nfo:fileSize 12341234 ;

    	# Mandatory for any nfo:DataObject
    	nie:url <file:///home/ivan/test/CC-test-big.png> .

Graphical Overview

Notation defined in this page

### Related information

This explanation is just a brief extract from the original Nepomuk NIE Ontology web page.

## NIE Ontology Classes

### nie:DataSource

A superclass for all entities from which DataObjects can be extracted. Each entity represents a native application or some other system that manages information that may be of interest to the user of the Semantic Desktop. Subclasses may include FileSystems, Mailboxes, Calendars, websites etc. The exact choice of subclasses and their properties is considered application-specific. Each data extraction application is supposed to provide it's own DataSource ontology. Such an ontology should contain supported data source types coupled with properties necessary for the application to gain access to the data sources. (paths, urls, passwords etc...)

Superclasses :

  rdfs:Resource,

Subclasses :

  --

In domain of :

  --

In range of :

  nie:rootElementOf, nie:dataSource,

### nie:InformationElement

A unit of content the user works with. This is a superclass for all interpretations of a DataObject.

Superclasses :

  rdfs:Resource,

Subclasses :

  --

In domain of :

  nie:usageCounter, nie:rootElementOf, nie:contentSize, nie:isLogicalPartOf, nie:characterSet, nie:licenseType, nie:hasPart, nie:hasLogicalPart, nie:keyword, nie:identifier, nie:license, nie:contentAccessed, nie:contentCreated, nie:version, nie:isStoredAs, nie:comment, nie:copyright, nie:links, nie:depends, nie:disclaimer, nie:description, nie:generator, nie:relatedTo, nie:legal, nie:plainTextContent, nie:language, nie:mimeType, nie:subject, nie:contentLastModified, nie:informationElementDate, nie:title,

In range of :

  nie:isLogicalPartOf, nie:isPartOf, nie:hasLogicalPart, nie:interpretedAs,

### nie:DataObject

A unit of data that is created, annotated and processed on the user desktop. It represents a native structure the user works with. The usage of the term 'native' is important. It means that a DataObject can be directly mapped to a data structure maintained by a native application. This may be a file, a set of files or a part of a file. The granularity depends on the user. This class is not intended to be instantiated by itself. Use more specific subclasses.

Superclasses :

  rdfs:Resource,

Subclasses :

  --

In domain of :

  nie:isPartOf, nie:created, nie:lastRefreshed, nie:interpretedAs, nie:dataSource, nie:byteSize, nie:url,

In range of :

  nie:hasPart, nie:isStoredAs, nie:links, nie:depends, nie:relatedTo,

## NIE Ontology Properties

### nie:contentSize

Type :

  --

Domain :

  nie:InformationElement,

Range :

  xsd:integer,

Superproperties :

  --

Subproperties :

  --

Cardinality :

  1

### nie:dataSource

Type :

  --

Domain :

  nie:DataObject,

Range :

  nie:DataSource,

Superproperties :

  dc:source,

Subproperties :

  --

### nie:created

Type :

  --

Domain :

  nie:DataObject,

Range :

  xsd:dateTime,

Superproperties :

  --

Subproperties :

  --

Cardinality :

  1

### nie:hasLogicalPart

Type :

  --

Domain :

  nie:InformationElement,

Range :

  nie:InformationElement,

Superproperties :

  --

Subproperties :

  --

### nie:generator

Type :

  --

Domain :

  nie:InformationElement,

Range :

  xsd:string,

Superproperties :

  --

Subproperties :

  --

Cardinality :

  1

### nie:rootElementOf

Type :

  --

Domain :

  nie:InformationElement,

Range :

  nie:DataSource,

Superproperties :

  --

Subproperties :

  --

Cardinality :

  1

### nie:url

URL pointing at the location of the resource. In cases where creating a simple file:// or http:// URL for a file is difficult (e.g. for files inside compressed archives) the applications are encouraged to use conventions defined by Apache Commons VFS Project at http://jakarta.apache.org/ commons/ vfs/ filesystems.html.

Type :

  --

Domain :

  nie:DataObject,

Range :

  xsd:string,

Superproperties :

  --

Subproperties :

  --

Cardinality :

  1

### nie:language

Language the InformationElement is expressed in. Users are encouraged to use the two-letter code specified in the RFC 3066

Type :

  --

Domain :

  nie:InformationElement,

Range :

  xsd:string,

Superproperties :

  --

Subproperties :

  --

Cardinality :

  1

### nie:isLogicalPartOf

Type :

  --

Domain :

  nie:InformationElement,

Range :

  nie:InformationElement,

Superproperties :

  --

Subproperties :

  --

### nie:version

Type :

  --

Domain :

  nie:InformationElement,

Range :

  xsd:string,

Superproperties :

  --

Subproperties :

  --

Cardinality :

  1

### nie:isStoredAs

Type :

  --

Domain :

  nie:InformationElement,

Range :

  nie:DataObject,

Superproperties :

  --

Subproperties :

  --

Cardinality :

  1

Note:

This property is deprecated

### nie:title

The title of the document

Type :

  --

Domain :

  nie:InformationElement,

Range :

  xsd:string,

Superproperties :

  dc:title,

Subproperties :

  --

Cardinality :

  1

Text indexed :

  This property is indexed, so it can provide results on text search

### nie:subject

The subject or topic of the document

Type :

  --

Domain :

  nie:InformationElement,

Range :

  xsd:string,

Superproperties :

  dc:subject,

Subproperties :

  --

Cardinality :

  1

Text indexed :

  This property is indexed, so it can provide results on text search

### nie:isPartOf

Type :

  --

Domain :

  nie:DataObject,

Range :

  nie:InformationElement,

Superproperties :

  --

Subproperties :

  --

### nie:hasPart

Type :

  --

Domain :

  nie:InformationElement,

Range :

  nie:DataObject,

Superproperties :

  nie:relatedTo,

Subproperties :

  --

### nie:mimeType

File Mime Type

Type :

  --

Domain :

  nie:InformationElement,

Range :

  xsd:string,

Superproperties :

  --

Subproperties :

  --

Cardinality :

  1

### nie:description

Type :

  --

Domain :

  nie:InformationElement,

Range :

  xsd:string,

Superproperties :

  dc:description,

Subproperties :

  --

Cardinality :

  1

Text indexed :

  This property is indexed, so it can provide results on text search

### nie:usageCounter

Type :

  --

Domain :

  nie:InformationElement,

Range :

  xsd:integer,

Superproperties :

  --

Subproperties :

  --

Cardinality :

  1

### nie:depends

Type :

  --

Domain :

  nie:InformationElement,

Range :

  nie:DataObject,

Superproperties :

  nie:relatedTo,

Subproperties :

  --

Cardinality :

  1

### nie:contentAccessed

Type :

  --

Domain :

  nie:InformationElement,

Range :

  xsd:dateTime,

Superproperties :

  nie:informationElementDate,

Subproperties :

  --

Cardinality :

  1

### nie:comment

Type :

  --

Domain :

  nie:InformationElement,

Range :

  xsd:string,

Superproperties :

  --

Subproperties :

  --

Cardinality :

  1

Text indexed :

  This property is indexed, so it can provide results on text search

### nie:interpretedAs

Type :

  --

Domain :

  nie:DataObject,

Range :

  nie:InformationElement,

Superproperties :

  --

Subproperties :

  --

Cardinality :

  1

### nie:informationElementDate

Type :

  --

Domain :

  nie:InformationElement,

Range :

  xsd:dateTime,

Superproperties :

  dc:date,

Subproperties :

  nie:contentAccessed, nie:contentCreated, nie:contentLastModified,

### nie:disclaimer

Type :

  --

Domain :

  nie:InformationElement,

Range :

  xsd:string,

Superproperties :

  nie:legal,

Subproperties :

  --

Cardinality :

  1

### nie:byteSize

File size in bytes

Type :

  --

Domain :

  nie:DataObject,

Range :

  xsd:integer,

Superproperties :

  --

Subproperties :

  --

Cardinality :

  1

### nie:identifier

Type :

  --

Domain :

  nie:InformationElement,

Range :

  xsd:string,

Superproperties :

  dc:identifier,

Subproperties :

  --

Cardinality :

  1

### nie:characterSet

Type :

  --

Domain :

  nie:InformationElement,

Range :

  xsd:string,

Superproperties :

  --

Subproperties :

  --

Cardinality :

  1

### nie:relatedTo

A common superproperty for all relations between a piece of content and other pieces of data (which may be interpreted as other pieces of content).

Type :

  --

Domain :

  nie:InformationElement,

Range :

  nie:DataObject,

Superproperties :

  dc:relation,

Subproperties :

  nie:hasPart, nie:links, nie:depends,

### nie:licenseType

Type :

  --

Domain :

  nie:InformationElement,

Range :

  xsd:string,

Superproperties :

  nie:legal,

Subproperties :

  --

Cardinality :

  1

### nie:contentCreated

Type :

  --

Domain :

  nie:InformationElement,

Range :

  xsd:dateTime,

Superproperties :

  nie:informationElementDate,

Subproperties :

  --

Cardinality :

  1

### nie:license

Terms and intellectual property rights licensing conditions.

Type :

  --

Domain :

  nie:InformationElement,

Range :

  xsd:string,

Superproperties :

  nie:legal, dc:rights,

Subproperties :

  --

Cardinality :

  1

### nie:contentLastModified

Type :

  --

Domain :

  nie:InformationElement,

Range :

  xsd:dateTime,

Superproperties :

  nie:informationElementDate,

Subproperties :

  --

Cardinality :

  1

### nie:copyright

Type :

  --

Domain :

  nie:InformationElement,

Range :

  xsd:string,

Superproperties :

  nie:legal, dc:rights,

Subproperties :

  --

Cardinality :

  1

### nie:plainTextContent

Plain-text representation of the content of a InformationElement with all markup removed. The main purpose of this property is full-text indexing and search. Its exact content is considered application-specific. The user can make no assumptions about what is and what is not contained within. Applications should use more specific properties wherever possible.

Type :

  --

Domain :

  nie:InformationElement,

Range :

  xsd:string,

Superproperties :

  --

Subproperties :

  --

Cardinality :

  1

Text indexed :

  This property is indexed, so it can provide results on text search

### nie:lastRefreshed

Type :

  --

Domain :

  nie:DataObject,

Range :

  xsd:dateTime,

Superproperties :

  dc:date,

Subproperties :

  --

Cardinality :

  1

### nie:keyword

Type :

  --

Domain :

  nie:InformationElement,

Range :

  xsd:string,

Superproperties :

  --

Subproperties :

  --

Text indexed :

  This property is indexed, so it can provide results on text search

### nie:links

A linking relation. A piece of content links/mentions a piece of data

Type :

  --

Domain :

  nie:InformationElement,

Range :

  nie:DataObject,

Superproperties :

  nie:relatedTo,

Subproperties :

  --

Cardinality :

  1

### nie:legal

A common superproperty for all properties that point at legal information about an Information Element

Type :

  --

Domain :

  nie:InformationElement,

Range :

  xsd:string,

Superproperties :

  dc:rights,

Subproperties :

  nie:licenseType, nie:license, nie:copyright, nie:disclaimer,

Cardinality :

  1