SELMA: A middleware platform for self- organizing distributed ...

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SELMA: A middleware platform for self- organizing distributed ...

SELMA: A middleware platform for selforganizing

distributed applications in

mobile multi-hop ad-hoc networks

Daniel Görgen, Hannes Frey, Johannes K. Lehnert, Peter Sturm

System software and distributed systems

University of Trier

Germany


Mobile multi-hop ad-hoc networks





Metropolitan sized

networking

Mobile devices

• Wireless communication

facilities

• Localized location computation

Direct communication only

within transmission range

Unpredictable network

topology changes due to

mobility

• Network partitions

• Permanent link failures


Mobile multi-hop ad-hoc networks





Metropolitan sized

networking

Mobile devices

• Wireless communication

facilities

• Localized location computation

Direct communication only

within transmission range

Unpredictable network

topology changes due to

mobility

• Network partitions

• Permanent link failures


Marketplace communication


Fixed geographic regions

• High device density

• Known position

Offer


Devices at market acting on

behalf of a user


Geographic routing of

agents/data

• To and from marketplaces

O


Negotiation at a marketplace

• Geographic limited

broadcast

• Topology-based Routing

R

Request


Definition of home zones

• Negotiation results are sent

back to a defined home

zone


UbiBay – A mobile auction system

Auction at marketplaces

• Intended for low value goods

• Direct neighborhood

Agents

• Auction agent

Controls the auction

• Discovery agent

Discovers all auctions at

marketplace

• Bid agent

Bids on behalf of a user

Auction Agent

Discovery Agent


UbiBay – A mobile auction system

Auction at marketplaces

• Intended for low value goods

• Direct neighborhood

Agents

• Auction agent

Controls the auction

• Discovery agent

Discovers all auctions at

marketplace

• Bid agent

Bids on behalf of a user

10

15

Bid Agent


Middleware platform overview

Application Agents

Service Agents


load duplicate ticket

A 1 A 2 A 3

monitoring

elimination

agent


Agent Platform

agent

movement

agent

transport

geographic

routing

hotspot

detection

map computation

marketplace

communication

marketplace

localization

Hardware abstraction

positioning

local unicast

local broadcast

neighbor discovery


Agent movement





To and from marketplaces

Geographic routing

• e.g. greedy algorithm

• Additional: course information


Messages can be carried over

network partitions

Message duplication to avoid

message losses

• Sender keeps messages until

reception is acknowledged

• Duplicated messages can be

detected on the marketplace

Losses are still possible

• Device crash

S

D


Communication at Marketplaces




More reliable communication

• High device density

• Network partitions are rare

• Message loss can be detected

Discovery

• Broadcast only in a small region

Discard messages outside

• Flooding or neighbor knowledge broadcasts

Negotiation

• Topology-based routing

• Broadcasts as above


Homezones

Sending Messages to User

• User is mobile

• Possibly hours later

Homezone

• Agent knows homezone

• High visit probability

• Faculty building, apartment

• Long waiting times

Links to current position

• Sequence of homezones

• Updates after movement

• Other devices needed


Services at marketplaces




Mobile service at marketplace

• Self organized creation

• Tries to stay

at marketplace

Load monitoring

• High network load

• Not enough resources

• Splitting and joining of

marketplaces

• Geographical disjoined regions

with high device density

Duplication detection

• Duplication due to permanent

link failures

• Duplicates ask service first


Summary

Prototype implemented

• Simulative, Emulative & real hardware

Already implemented Applications

• UbiBay, Electronic ride board, Distributed

Newsgroup,…

Application Domain

• Based on Offer and Demand

• No hard time constraints

Future Work

• Improved version is planned

• Increase probability to communicate over partitions

• Learning network topologies

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