International Workshop on Wireless Ad-hoc Networks Service ... · International Workshop on...
Transcript of International Workshop on Wireless Ad-hoc Networks Service ... · International Workshop on...
2 June 2004MJ Blange, IP Karkowski, BCB Vermeulen 1
TNO Physics and Electronics Laboratory
Service Discovery inHeterogeneous Wireless Networks
International Workshop on Wireless Ad-hoc Networks
IWWAN, 2 June 2004IP Karkowski 2
Overview• Possible approaches to handling vertical handovers.• SPEARS architecture.• Service discovery concepts in SPEARS.• Implementation details.• Experimental results.• Conclusions and future work.
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Vertical handovers• Lower levels of the OSI protocol stack.• IP layer.• Middleware layer between networking protocols and
application.
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LAN
The SPEARS architectureCurrent implementation based on:• Within IMT: Bluetooth (PAN)• Between IMT’s: WiFi ad-hoc network (LAN)• Public network: GPRS (WAN)
GPRS basisstation
WAN
PAN
PAN
PAN
PAN
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Motivation• Robustness• No central server• Flexibility of the network configuration.
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Service discovery middleware• Services• Lookup servers
• Global lookup server (WAN)• Local lookup servers (LAN)
• Registration of services• Usage of services
SERVICEPROVIDER
SERVICEREQUESTER
FIND
SERVICEREGISTRY
SERVICEREGISTRY
SERVICEDESCRIPTION
INTERACT
PUBLISH
SERVICEPROVIDER
REQUESTER
SERVICEPROVIDER
REQUESTER
FIND
PUBL
ISH
SERVICEDESCRIPTION
SERVICE
CLIENT
FIND
PUBLISH
SERVICEDESCRIPTION
SERVICE
CLIENT
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Service / Network Outage (Case 1)
LAN
WAN
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Service / Network Outage (Case 2)
WAN
LAN
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Service / Network Outage (Case 3)
WAN
LAN
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SPEARS Implementation of ServiceDiscoveryEssential requirements:• Multicasting support.• Restricting multicast to LAN.• Routing of IP packages between mobile nodes
through WAN.
Highlights:• Combination of AODV & Mobile IP.• Based on Jini™ from Sun Microsystems.• SPEARS specific extensions.
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Implementation aspects• ‘Codebase’ problem - must be different in WAN and
LAN registrations.• SpearsClassLoader• setCodebase() member function.• First register at WAN, then LAN.
• Service type identification - applications must be ableto see which service version (LAN or WAN) they areabout to use.• Services annotated with an attribute indicating service type.
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Experimental results
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Conclusions• Vertical handovers at middleware layer.• Practical implementation in Jini.