1/17 DIANE Project Betreuer: Birgitta König-Ries, Michael Klein An approach to Support Service Discovery in Mobile Ad-hoc Networks - Concept and Simulation - Universität Karlsruhe Institute for Program Structures and Data Organization Universität Karlsruhe Diplomarbeitsvortrag Eduardo Ponz

2/17 Introduction Mobile devices are becoming very popular 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? Summary Implementation Concept - Information - Protocols Scenario Introduction Mobile phonePDALaptop

3/17 Problems with Mobile Ad-hoc Networks Highly dynamic topology due to - node movement - node fluctuation - appearing obstacles No dedicated server, no physical infrastructure Summary Implementation Concept - Information - Protocols Scenario Introduction

4/17 Service Ring (1) Group nodes offering similar services into a Service Ring (SR) DIANE Approach: Service Rings One node of the ring becomes the Service Access Point (SAP) This node has the description of all the services of the ring Summary Implementation Concept - Information - Protocols Scenario Introduction

5/17 Service Ring Model Service Ring (2) Many aspects have to be considered in the service ring model: Service description Service integration Motivation Summary Implementation Concept - Information - Protocols Scenario Introduction Service discovery

6/17 Service Discovery Initialization Protocol - How is a service ring built? Ring Routing Protocol - How do we find the proper service ring? Node Routing Protocol - How do we find the proper service inside a service ring? Actualization Protocol - How should the system react to device movement and fluctuations? Service discovery implies many different aspects Ring and Service Information - What information should be stored in the nodes? Summary Implementation Concept - Information - Protocols Scenario Introduction

7/17 Service Description Out of the scope of the Diploma Thesis Service Discovery Ring and Service Information Information about the service ring has to be locally stored in the nodes Service Information Ring Information Node Information - Ring ID - Service Type of the SR - Node ID, Cycle ID - Reachable nodes - Predecessor and Successor - Services offered by the node Ring Routing Protocol Node Routing Protocol Summary Implementation Concept - Information - Protocols Scenario Introduction

8/17 Initialization Protocol We ask if there is any SR nearby Service Ring? How to build a service ring from scratch else SET node as SAP If SR then CONNECT to SR CONNECT: If there is only one node of the SR reachable then Build a bridge If there are more nodes of the SR reachable then Insert into SR between the two closest linked nodes - A second node appears - A third node appears - One node appears SR? SAP Summary Implementation Concept - Information - Protocols Scenario Introduction

9/17 Node Routing Protocol (1) How to find the proper service inside a SR Routing in a simple SR is trivial Each node has one successor and one predecessor Service D? Service D Service A Service B Service C How do we deal with intricate rings? Thanks! No Yes, but NOT me No YES but... We only have to route the message to the successor node D Node X X‘s Predecessor X‘s Successor Summary Implementation Concept - Information - Protocols Scenario Introduction

10/17 Node Routing Protocol (2) Service rings may be intricate Some nodes have more than one successor and predecessor Some nodes have twice the same successor or predecessor To properly route a message: - A message traveling along the SR will keep track of which cycles are already visited C1 C2 C3 C4 C5 - We divide the service ring into cycles Summary Implementation Concept - Information - Protocols Scenario Introduction

11/17 Node Routing Protocol (3) Example of routing a message: Algorithm for nodes with many successors: Continue in the same cycle Service D? - 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 Routing complete! Summary Implementation Concept - Information - Protocols Scenario Introduction C1 C2 C3 C4 C5

12/17 Ring Routing Protocol How do we find the proper SR? We have many different service rings that offer different services Yellow service Blue service Green service Indigo service The SAPs are connected with each other Ring of SRs The SAPs store the information about ring routing Summary Implementation Concept - Information - Protocols Scenario Introduction A message can now jump to other SRs

13/17 Actualization Protocol (1) Reactions to device movements and fluctuations Typical node fluctuations are: Movement Logging - Into a SR - Login into a SR - Out of a SR - Logout of a SR - Sudden disconnection Summary Implementation Concept - Information - Protocols Scenario Introduction

14/17 Actualization Protocol (2) Example of sudden disconnection algorithm: - Node B vanishes C B D E F A - Node A needs to link with C C is not reachable! Backward routing - Node C looks for reachable nodes - Node C requests information - Reachable nodes send info I I I - C processes the info and chooses the best node - X marks C as successor - A marks X as successor X - The SR is successfully closed - C sends control message to X - X sends control message to A Note: Backward routing should be only used if everything else fails Summary Implementation Concept - Information - Protocols Scenario Introduction

15/17 Implementation A simulation of the Node Routing Protocol in a service ring is currently under development QualNet is the network simulator used for this purpose Summary Implementation Concept - Information - Protocols Scenario Introduction - Custom protocols can be developed - There are pre-written protocol models - QualNet models complex wireless networks

16/17 Summary and Future Work Summary: A basic mechanism to service discovery has been proposed DevelopedConceptSimulation Ring and Node Information- Initialization Protocol- Node Routing Protocol in progress Ring Routing Protocol in progress Actualization Protocol- Future Work: Optimization to the proposed protocols Implementation of all the protocols in QualNet Prototype in a real scenario Summary Implementation Concept - Information - Protocols Scenario Introduction

17/17 Thank you! More information on our project web page: Are there any questions? Thank you for your attention!