DIANE Project

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Universität Karlsruhe GERMANY
Information Services to Support E-Learning in
Ad-hoc Networks
The First International Workshop on Wireless
Information Systems 2. - 3. April 2002 Ciudad
Real, Spain
Birgitta König-Ries, Michael Klein
Universität Karlsruhe Institute for Program
Structures und Data Organization
DIANE Project
http//www.ipd.uni-karlsruhe.de/DIANE
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Our Scenario
More on SQL?
Anna
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Problems with mobile Ad-hoc Networks

• Highly dynamic topology due to
• node movement
• node fluctuation
• appearing obstacles

• No dedicated server, no physical infrastructure

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Work on Ad-hoc Networks
Application
Transport
IP Network
Data Link MAC
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Resulting Tasks
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Service Discovery (1)
Our Approach Service Rings

• Group devices offering similar services to rings
• "Similar" can be derived from ontology

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Service Discovery (2)
Group SAPs to larger rings, as though they were
single devices
relational Algebra
SQL
Normalization
We call the highest level ring world ring. It
covers all services (directly or indirectly).
Every device is (at least an indirect) member of
it.
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How to use these rings?
Exercise on SQL?
Finding a service
Is not included.
!
Does not match.
relational Algebra
!
?
?
?
Is included!
Is not included.
?
?
SQL
Normalization
relational Model
Is included!
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Advantages of Service Rings

• Routes are known
• no flooding necessary
• strictly decentralised
• descending only in suitable subrings
• routing way unique, no exploring (as in graphs)

• Answer messages always possible
• even when connections are unidirectional

• Message loss discoverable
• each message returns after having visited all
  ring members

• Two dedicated neighbors
• structural integrity can be maintained locally

• Defined service management position
• service changes are submitted to the local SAP
  only, not broadcasted through the whole net

• No central device
• each node is basically equal, work is distributed
  equally
• no overall important nodes (in contrast to stars
  or trees)

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Service Description
Separate technical service description from
document description
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Document Description (1)
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Document Description (2)
Concrete Document or Document Template
Document
Information
Keyword
Author Format Size ...
Title Description ...
contains
is described by
0..
1
0..
1..
is part of
ontologicalrelationship
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Service Description Example (1)
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Service Description Examples (2)
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Current Research on Service Rings
Locally formed, hierarchical rings

• Ideas
• At the beginning, group rings according to their
  spatial proximity
• Split rings that are too big into thematically
  coherent subrings
• Rings are "logical", their connections are
  established by an existing Routing Protocol (like
  DSR)

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Summary
Service Description by separating different
issues for services
Application
Service Discovery by the use of semantical
service rings
Transport
IP Network
Data Link MAC
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Thank you!
Thank you for your attention!
More information on our project web
page http//www.ipd.uni-karlsruhe.de/DIANE/en