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Review of Paper:. Johan Hjelm “Position dependent services using metadata profile matching” Youyong Zou Apr.15,2001. User Position and Information. User position can change between requests for information. Different information sets can be generated for different positions

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Review of paper

Review of Paper:

Johan Hjelm“Position dependent services using metadata profile matching”

Youyong Zou


User position and information

User Position and Information

  • User position can change between requests for information. Different information sets can be generated for different positions

  • The location can be declared, and a rule-based system can determine the relevance of the location for the user, based on the users input and the metadata declaration of the information object for the location.

  • 80 % of all information has a relation to a location - in other words, is position-dependent, according to the British National Geographical Data Framework

So what is problem with position

So, what is problem with Position?

  • We defined a mechanism which includes the position as a property of the client in the content negotiation.

  • The content negotiation can take place over a number of different protocols, using the W3C standardized Composite Capabilities/Preference Profile format [CC/PP].

  • However, a number of problems are unresolved, most urgently the number of location metadata standards that exist in the world – more than 30 !  

Determine the user position

Determine the User Position

  • A number of methods exist to determine the position:

    • GPS

    • Differential GPS

    • Network-based positioning

    • User input

  • The position of the user can either be retrieved into the user device, or into a proxy in the network, depending on the method of positioning.

  • The easiest way download the position information from a device into an origin server is to handle the information in the TerminalLocation attribute of the CC/PP profile.

Metadata and context encoding

Metadata and context encoding

  • Use RDF to for Metadata

  • Determinate the relevant in the current context of the user : The device reports its position to a server, which identifies documents relevant in that position, and forwards them to the user.

  • Traditional full-text indexing cannot solve the problem of providing the information that is relevant in the user context.

Position relevance in metadata

Position-relevance in metadata

  • Information is location relevant if it can provide the user or an agent acting on his behalf with information that can affect the situation of the user.

  • Define some elements:

    map, FieldNote, person, dataitem, data, temporal, spatial and comment.



  • A location may not be relevant to a user at all times, but take on a relevance at a certain time

  • Users may also make requests for information that is not currently relevant, but will be at the time of the validity of the request.

  • Relevance may also depend on the role of the user.

The position layer gml

The position layer: GML

  • Geographical Markup Language (GML) by the Open GIS Consortium , based on XML, and can be expressed as RDF.

  • GML represents the OGC Abstract Specification Simple Features as XML, which describe an object model for geometry, as curves, surfaces, and geometry collections.

Event markup ski

Event markup: SKi

  • SKiCal format, by Svenska Kalenderinitiativet , in RDF.

  • An example SKiCAL event description in RDF :



    <RDF:Description about="VCALENDAR">



    <ICAL:uid>[email protected]</ICAL:uid>

    <ICAL:organizer_cn>Dean Walt Wittman</ICAL:organizer_cn> <ICAL:organizer_mailto>[email protected] </ICAL:organizer_mailto>

    <SKI:otheragents>Christian Concerts of America" Inc. </SKI:otheragents>

    <SKI:association>Catholic Church of North America, Diocese of Chicago</SKI:association>

    <SKI:title>Universal Salvation Tour</SKI:title>

    <SKI:performer>Cross Brothers</SKI:performer>

    <SKI:part_of>Decatur For Christ Week</SKI:part_of>

Matching metadata and profile

Matching metadata and profile

  • Different parameters will require different matching algorithms, depending on the data type.

  • The matching can be integrated with the web server.

  • The CC/PP profile can be cached in the server and re-used as long as it is valid.

  • SKi format can easily be matched with the position and temporal preferences of the user.

Composite capability preference profile

Composite Capability/Preference Profile

  • CC/PP profile is a collection of the capabilities and preferences associated with user and the agents used by the user to access the World Wide Web.

  • The basic data model for a CC/PP is a collection of tables.

  • The profile is associated with the current network session or transaction

  • A collection of "default" properties , update of a profile to the profile repository

Wap forum uaprof


  • The Wireless Application Protocol system : bringing information to mobile telephones.

  • The User Agent Profile (UAProf) specification extends WAP 1.1 to enable the end-to-end flow of a User Agent Profile, also referred to as Capability and Preference Information (CPI)

Review of paper


  • CPI is based on CC/PP , seeks to minimize wireless bandwidth consumption

  • Each network element may add additional profile information to the transmitted CPI.

  • Origin servers, gateways, and proxies can use the CPI to ensure that the user receives content that is particularly tailored for the environment

  • CPI permits the origin server to select and deliver services that are appropriate to the capabilities of the requesting client



  • This paper demonstrate the concept: A meta-description of the information object can be matched with the users preferences and device capabilities.

  • Hope to will find wide acceptance, as it enables totally new classes of services.

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