ECS-TV System Details

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Part 7 - RDF & The ECS-TV Ontology

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ECS-TV uses both mysql and a 3Store to store the information required for all the various interfaces. Mysql handles the data related to the live services such as the central playlist while an RDF triple store (3Store) is used to store all the data related to stored lectures and other content available via the interactive system.

The ECS-TV Interactive Database

    This section gives a detailed outline of the data used in the interactive system including the namespaces involved. This includes ECS-TV's own namespace, the ontology of which is also decumented in this section.

Namespaces
    A namespace consists of a unique name that identifies an organization that has developed an XML schema. A namespace is identified via a Uniform Resource Identifier (URL or URN). The use of namespaces allows the definition of an element to be unambiguously identified with a URI, even though a label may occur in many metadata sets. In more general terms, one can think of any closed set of names as a namespace. Thus, a controlled vocabulary consisting of a set of metadata elements such as DC, or the set of all URLs in a given domain can be thought of as a namespace. Global namespaces such as the Dublin Core namespace are managed by the authority that is in charge of that particular set of terms and a vocabulary is made available which can be easily referenced by others.

The following namespaces are used in the ECS-TV project:

In RDF namespaces can be defined at the top of the XML document as namespaces and prefixes are then used throughout the document. Thus foaf:name becomes http://xmlns.com/foaf/0.1/name when stated as a full URI.

The ECS-TV Namespace

NOTE:For full details of the data stored by ECS-TV please refer to the Project Report by David Tarrant for ECS-TV dated May 2000, section 4.9.
An Electonic copy is available here.

    Classes/Objects
      The ontology has 2 main parts. The first represents the Classes, which each item is an instance of. This triple is commonly represented in RDF as subject -> rdf:type -> Class. Figure 7.1 shows the classes defined in the ECS-TV ontology.

Attribute	Description
ecstv:Media	Define an item as a media item, used in conjuction with rdfs:type
foaf:Organisation	Define your subject as an Organisation.
ecstv:University	University - Type of Organisation.
ecstv:School	School - Type of Organisation.
ecstv:Group	Group - Type of Organisation.
foaf:Person	Define your subject as a Person.
ecstv:Company_Member	Company Member - Type of Person.
ecstv:University_Member	University Member - Type of Person.
ecstv:Staff	Staff - Type of University_Member.
ecstv:Academic_Staff	Academic related staff - Subclass of Staff
ecstv:Systems_Staff	Systems related staff - Subclass of Staff
ecstv:Student	Student - Type of University_Member.
ecstv:Degree	Define your subject as a degree.
ecstv:Unit	Define your subject as a unit, usually this is related to a Degree.

    Predicates
      Predicatess relate a subject to an object or data, it is very important that these can be parsed efficiantly to make inferences upon the data. It is advised to use predicates from existing popular namespaces which are already well established however this is not always posible therefor some in our own namespace have to be used. Figure 7.2 shows those predicates specifically designed for use in the ECS-TV system.

Attribute	Relates to	Description
ecstv:partOf	All but Media	Information regarding stating that the subject is partOf the Object.
ecstv:providedBy & ecstv:hasProvider	Media and Units	Relates to the provider of the content in question, not this is different from owner as provider maybe outside of the scope of the local organisation.ecstv:hasProvider due to be depricated in the near future.
ecstv:hasCourseRelation	Media	This item is a direct rdf:resource link to a Unit object.
ecstv:hasUniversityRelation	Media	This item is a direct rdf:resource link to a University object. Intended for deprication in the near future to be replaced with ecstv:providedBy
ecstv:hasSchoolRelation	Media	This item is a direct rdf:resource link to a School object. Intended for deprication in the near future to be replaced with ecstv:providedBy
ecstv:hasGroupRelation	Media	This item is a direct rdf:resource link to a Group object. Intended for deprication in the near future to be replaced with ecstv:providedBy
ecstv:hasAudio	Media	Audio object relating to the current item.
ecstv:hasMedia	Media	Reference to full media relating to the current item.
ecstv:sequenceNumber	Media	Sequence number of this item if part of a set.
ecstv:acl	Media & Person	The items "Access Control List" stating what permissions are required in order to be able to view the item.
ecstv:status	Person	A persons status at an organisation such as a university eg, undergrad, postgrad & staff.
ecstv:memberOf	Person	A persons memberships as direct rdf:resource object links.
ecstv:visibility	Person	A persons visibility on the web (local and global).
ecstv:submission	Person	Provides the access rights for a person to be able to submit content to the system, specific to ECS-TV. Should really be a hidden attribute, i.e. not in this document!
ecstv:organisation_name	Company Member	The name of the Organisation a company member works for.
ecstv:department_name	Company Member	The name of the Departmant with an Organisation a company member works for.
ecstv:ucas_code	Degree	The Degree code.
ecstv:yearOfStudy	Degree & Units	Year of study of the Degree item.
ecstv:semesterOfStudy	Unit	Relating to course details this is a spcific field which relates a course to its period of study.
ecstv:facultyUnitCode	Unit	Relating to course details this is a spcific field which relates a course to a University wide Faculty code, note that more than one faculty code could apply to a single course, hense this field is not unique.
ecstv:compulary	Unit	States if a Unit is compulsary on a program of study.

    ECS-TV Database Structure
      Figure 7.3 shows the relationships drawn between the many objects in the ECS-TV database, this entity relationship diagram only shows those relations required to be supplied by the users to keep the structure intact. Other inferences are drawn upon the data based upon those realtions provided by the users. Figure 7.4 shows the current structure of each 'table' within the database system, the data from these virtual tables in then used to produce objects of the classes outlined in figure 7.1.

      Note: The key here tells us which fields require an rdf:resource link to another object. The majority of these relationships are shown in figure 7.3 above. All other items expect a simple plain text (CDATA) input.

KEY
	CData: Plain text data
	Resource: Link to other object/resource.

ecstv:Unit ecstv:providedBy ecstv:partOf rdfs:label foaf:name ecstv:facultyUnitCode ecstv:yearOfStudy ecstv:semesterOfStudy ecstv:compulsary	ecstv:Degree ecstv:providedBy ecstv:ucas_code rdfs:label foaf:name ecstv:yearOfStudy	ecstv:University rdfs:label foaf:name contact:address contact:phone contact:fax foaf:homepage foaf:mbox contact:mailbox
ecstv:School ecstv:partOf rdfs:label foaf:name contact:address contact:phone contact:fax foaf:homepage foaf:mbox contact:mailbox	ecstv:Group ecstv:partOf rdfs:label foaf:name contact:address contact:phone contact:fax foaf:homepage foaf:mbox contact:mailbox	ecstv:University_Member foaf:surname foaf:firstName foaf:mbox contact:mailbox ecstv:memberOf ecstv:status contact:address contact:phone ecstv:int-tel contact:fax foaf:homepage foaf:workplaceHomepage
ecstv:Company_Member foaf:surname foaf:firstName foaf:mbox contact:mailbox ecstv:status ecstv:organisation_name ecstv:department_name contact:address contact:phone contact:fax foaf:homepage foaf:workplaceHomepage	Course_Lecture ecstv:hasUniversityRelation ecstv:hasSchoolRelation ecstv:hasGroupRelation foaf:name rdfs:label ecstv:sequenceNumber ecstv:extraInfo ecstv:hasProvider ecstv:hasCourseRelation	Seminar_Lecture ecstv:hasUniversityRelation ecstv:hasSchoolRelation ecstv:hasGroupRelation foaf:name rdfs:label ecstv:extraInfo ecstv:hasProvider

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