DIANE Project

1
Universität Karlsruhe
An approach to Support Service Discovery in
Mobile Ad-hoc Networks - Concept and Simulation -
Diplomarbeitsvortrag Eduardo Ponz
Betreuer Birgitta König-Ries, Michael Klein
Universität Karlsruhe Institute for Program
Structures and Data Organization
DIANE Project
http//www.ipd.uni-karlsruhe.de/DIANE
2
Introduction

• Mobile devices are becoming very popular

Introduction
Scenario
Concept - Information - Protocols
Implementation
Summary

• We want to link these devices in mobile ad-hoc
  networks and offer services

• How do we search for a service in such a network?

3
Problems with Mobile Ad-hoc Networks
Introduction
Scenario
Concept - Information - Protocols
Implementation
Summary

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

• No dedicated server, no physical infrastructure

4
Service Ring (1)
DIANE Approach Service Rings
Introduction

• Group nodes offering similar services into a
  Service Ring (SR)

Scenario
Concept - Information - Protocols
Implementation
Summary

• One node of the ring becomes the Service Access
  Point (SAP)

• This node has the description of all the
  services of the ring

5
Service Ring (2)
Many aspects have to be considered in the service
ring model
Introduction
Scenario
Concept - Information - Protocols

• Service description

• Service discovery

Implementation
Summary

• Service integration

• Motivation

6
Service Discovery
Service discovery implies many different aspects
Introduction
Scenario

• Ring and Service Information
• - What information should be stored in the nodes?

Concept - Information - Protocols

• Initialization Protocol
• - How is a service ring built?

Implementation
Summary

• Node Routing Protocol
• - How do we find the proper service inside a
  service ring?

• Ring Routing Protocol
• - How do we find the proper service ring?

• Actualization Protocol
• - How should the system react to device movement
  and fluctuations?

7
Ring and Service Information
Information about the service ring has to be
locally stored in the nodes
Introduction
Scenario
Concept - Information - Protocols
Implementation
Summary

• Service Information

• Services offered by the node

8
Initialization Protocol
How to build a service ring from scratch
Introduction
- One node appears
Scenario
SAP
Concept - Information - Protocols
- A second node appears
- A third node appears
Implementation
Service Ring?
We ask if there is any SR nearby
SR?
Summary
SR?
9
Node Routing Protocol (1)
How to find the proper service inside a SR
Introduction

• Routing in a simple SR is trivial

but...
Scenario
Concept - Information - Protocols
No
Xs Successor
Service D?
Node X
Yes, but NOT me

• Each node has one successor and one predecessor

Implementation
Thanks!
Summary
Xs Predecessor

• We only have to route the message to the
  successor node

YES
No

• How do we deal with intricate rings?

10
Node Routing Protocol (2)
Service rings may be intricate
Introduction
Scenario
Concept - Information - Protocols
C2
C4
Implementation
C1
Summary
C5
C3

• Some nodes have more than one successor and
  predecessor

• Some nodes have twice the same successor or
  predecessor

To properly route a message
- We divide the service ring into cycles
- A message traveling along the SR will keep
track of which cycles are already visited
11
Node Routing Protocol (3)
Example of routing a message
Routing complete!
Introduction
Service D?
Scenario
Concept - Information - Protocols
C2
C4
Implementation
C1
Summary
C5
C3
Algorithm for nodes with many successors

• Continue in the same cycle

- If we have twice the same successor - If the
other cycles have been partially visited

• Jump to another cycle

- If the other cycle is a not visited bridge - If
the other cycle is a not visited cycle
12
Ring Routing Protocol
How do we find the proper SR?
Introduction
Scenario
Concept - Information - Protocols
Implementation
Summary
The SAPs are connected with each other

• The SAPs store the information about ring routing

• A message can now jump to other SRs

13
Actualization Protocol (1)
Reactions to device movements and fluctuations
Introduction
Scenario
Concept - Information - Protocols
Implementation
Summary
Typical node fluctuations are

• Movement

• Into a SR

• Out of a SR

• Logging

• Login into a SR

• Logout of a SR

• Sudden disconnection

14
Actualization Protocol (2)
Example of sudden disconnection algorithm
Introduction
- Node B vanishes
Scenario
- Node A needs to link with C
Concept - Information - Protocols
C is not reachable!
F
A
Implementation
Summary
- Node C looks for reachable nodes
X
E
- Node C requests information
- Reachable nodes send info
- C processes the info and chooses the best node
C
D
- C sends control message to X
- X marks C as successor
Note Backward routing should be only used if
everything else fails
- X sends control message to A
- A marks X as successor
- The SR is successfully closed
15
Implementation
A simulation of the Node Routing Protocol in a
service ring is currently under development
Introduction
Scenario
Concept - Information - Protocols

• QualNet is the network simulator used for this
  purpose

Implementation
Summary
- QualNet models complex wireless networks
- There are pre-written protocol models
- Custom protocols can be developed
16
Summary and Future Work
Summary
Introduction

• A basic mechanism to service discovery has been
  proposed

Scenario
Concept - Information - Protocols
ü
Implementation
ü
Summary
ü
ü
ü
Future Work

• Optimization to the proposed protocols
• Implementation of all the protocols in QualNet
• Prototype in a real scenario

17
Thank you!
Thank you for your attention!
More information on our project web
page http//www.ipd.uni-karlsruhe.de/DIANE