Wireless Sensor
Network Issues
김기형
(kkim@yu.ac.kr)
Network Computing Lab
영남대학교
Middleware in MANET (KRNET2004)
Contents
http://folk.uio.no/paalee
z Introduction to middleware technologies for MANET
z Related works on service discovery protocols
•
•
•
•
•
•
Blutooth SDP
SLP (IETF RFC2608)
Jini (http://www.jini.org )
Salutation (http://www.salutation.org )
UPnP (http://www.upnp.org )
JXTA
z Service advertisement and discovery mechanisms in Ad
Hoc networks
z Proposed service discovery mechanism in MANET
http://www.unik.no/personer/paalee
Middleware in MANET (KRNET2004)
Characteristics and Core Middleware Services for
MANET
http://folk.uio.no/paalee
z Characteristics of MANET
▬
Ref: T.Plagemann et.al., “Towards Middleware Services for Mobile Ad-hoc Network
Applications,” Proceedings of the Ninth IEEE Workshop on Future Trends of Distributed
Computing Systems(FTDCS’03)
▬ Typical application scenarios for MANET
– Emergency situations, Business meetings
– Æ Common key element of MANET is Information access and
sharing
▬ Three different types of information sources
– Mobile end-user devices, stationary devices, and the Internet
z Core Middleware Services in MANET
▬ M. Avvenuti et. al., “Core Services in a Middleware for Mobile Ad Hoc Networks,
FTDCS’03
▬ Logical mobility
¾ Object communication and migration (e.g. via RMI))
▬ Lookup service
http://www.unik.no/personer/paalee
Middleware in MANET (KRNET2004)
Searching for Peers
z Searching for peers is like trying to call someone by phone
z Reasons for calling a peer
▬
▬
▬
▬
To give information
To get information
To ask for a service
To ask for content
z Where is the peer information stored? (Peer advertisement)
▬ Locally (local address book)
▬ Centrally (Centralized directory service: phone book)
¾
¾
¾
¾
Napster (indexing by content id)
IRC, Skype (indexing by username)
DNS (DNS server: indexing by machine name)
SIP (indexing by SIP address)
▬ Remotely(friends’ address book)
¾
¾
¾
¾
¾
¾
Peer (or service) advertisement, peer discovery
Distributed directory service
SLP (passive advertising)
JXTA (PDP)
SSDP
Salutation
Ref: T. Saridakis, “Peer advertisement, discovery and Inquiry”, Nokia 2003
Middleware in MANET (KRNET2004)
P2P Network Protocols
z Two main protocols
▬ Node Discovery: Used by a new node joining the
network to discover existing nodes in the network and
connect to them
▬ Service(Resource) Discovery: Used by a node to
locate resources present on other nodes
Middleware in MANET (KRNET2004)
Node Discovery Protocol
Address Server
(contains addresses of 2. Return node
well known nodes)
address
1. Request address of
at least one existing node
from Address Server
Newly
Joining
Node
Ping Message
Pong Message
Ref: http://faculty.ist.unomaha.edu/pdasgupta/courses/spring2004/csci3830/slides/lec19.ppt
Middleware in MANET (KRNET2004)
Service (Resource) Discovery Protocol
Node
Starting
Query
Query Message
QueryHit Message
Middleware in MANET (KRNET2004)
Related Works on Service Discovery
Protocols
•Blutooth SDP
•SLP (IETF RFC2608)
•Jini (http://www.jini.org )
•Salutation (http://www.salutation.org )
•UPnP (http://www.upnp.org )
•JXTA (http://www.jxta.org )
Middleware in MANET (KRNET2004)
Comparison of Existing Service Discovery Protocols
SLP2
JINI
Salutation
UPnP
Bluetooth
SDP
(main) developer
IETF
Sun
Salutation
consortium
Microsoft
Microsoft + Intel
Network transport
TCP/IP
Independent
Independent
TCP/IP
Bluetooth
OS & platform
dependent
Independent
Independent
dependent
Independent
Programming
language
Independent
java
Independent
Independent
Independent
Attributes
searchable
yes
yes
yes
no
yes
Service cache
manager
optional
optional
mandatory
no
no
scoping
scopes
groups
no
no
Not necessary
characteristics
Very lightweight
Code mobility,
java integration
Network
independence,
service access
Focus on
hardware
High integration
Qualification for ad
hoc
-
+
+
-
+
integration
-
+
-
-
++
scalability
+
+
+
-
--
Michael Dyrna , Peer2peer Network Service Discovery for Ad-hoc Networks Hauptseminar im Wintersemester 2003 / 2004
11.12.2003
Middleware in MANET (KRNET2004)
Bluetooth: Piconets for wireless devices
z Low-power, short-ranger(10meter), wireless ratio
system
z 2.4GHz ISM (Industrial Scientific and Medical) band
z Supports Isochronous and asynchronous service
z Bluetooth devices can form ad hoc network called
piconets.
z States
▬
▬
▬
▬
▬
standby – conserving power & waiting to connect
inquire – searching for nearby Bluetooth devices
page – connecting to another Bluetooth device.
connected – connected to another Bluetooth device
hold & park – participating in a piconet
Middleware in MANET (KRNET2004)
Bluetooth SDP (Service discovery protocol)
SDP uses a request/response mode
Request PDU (Protocol Data Unit) - Response PDU
Bluetooth L2CAP transport protocol
SDP provides a simple API for enumerating the
devices in range and browsing available services
z SDP server contains Service records (service
attribute, service class)
z
z
z
z
Client
application uses
API to search
for available
services
Client
application
Server
Application
SDP requests
SDP
SDP
Client
Client
SDP responses
Middleware in MANET (KRNET2004)
SDP
SDP
Server
Server
SLP Overview
z SLP is natural and now standardized scheme for find services
z Service Location is one of the next big problem areas for mobile
computing
z Implementation and deployment can be very simple or much more
sophisticated
z SLP provides a dynamic configuration mechanism for applications in LAN
z User Agent (UA) : application ask for service
z Service Agent (SA) : provide service, advertises service handles
containing the necessary locator information.
z Directory Agent (DA) : centralized repository for advertised service.
z SLP allows
9 Clients to find Servers by type and desired attributes
9 Service to advertise themselves
9 Scope to organize services using arbitrary polices
Middleware in MANET (KRNET2004)
SLP Agent Model
Directory
Directory
Agent
Agent
Service
Service
Agent
Agent
Corporate
Corporate
intranet
intranet
DHCP
DHCP
Middleware in MANET (KRNET2004)
User
User
Agent
Agent
Interactions among DA, UA and SA
Client
Service
Service Request (Multicast)
UA
SA
Service Reply
Se
R e rvi
qu ce
es
t
Se
rv
ic
e
Re
e
c
i
rv ster
e
S gi
Re
pl
y
DA
DA
ce
i
rv
e
S
Middleware in MANET (KRNET2004)
e
g
ed
l
w
o
kn
c
A
URLs used with Service Location
General form
“service:”<srctype>”://”<addrspec>
addrspec – DNS, IP
(ex)
“service:tftp://myhost”
“service:tftp://bad.glad.org:8080”
“service:printer://hostname”
“service:lpr://motels.eng.sum.com/MPK15-214
Middleware in MANET (KRNET2004)
SLP Message Type
Version
Function
Length, contd. O F R
Length
reserved
Next Ext offset
Next Extension offset, contd.
XID
Language Tag Length
Language Tag
Length – entire SLP message
O(overflow) – is set when a message’s length exceeds
F(Fresh) – is set on every new SrvReg
R(request multicast) - is set when multicasting or broadcasting
request.
XID is set to a unique value for each unique request
Middleware in MANET (KRNET2004)
Jini: Mobile Java Code
z Jini is a service discovery and advertisement system.
z Platform independence
z Required each device either to run a java virtual
machine (JVM) or to associated itself with a device.
z Consist of services, lookup servers that catalog
available services, and Clients that require services.
z Lookup server : multicast announcement protocol
z Services or client : multicast request protocol
z Java’s security model (digital certificate, encryption)
Middleware in MANET (KRNET2004)
Operation of Jini
Lookup server
Client
Lookup table
Service
Java
code
(proxy)
register() method :
ServiceItem
ServiceRegistration
loopkup()
method :ServiceTemplate
ServiceMatches
Middleware in MANET (KRNET2004)
Operation of Jini (II)
Lookup
Service
Lookup
Service
Service
object
Service
attributes
Service
object
Service
attributes
Client
(1)
Service
provider
Service
object
Service
attributes
A service provider register a
service object and its service
attributes with the lookup service
Client
(2)
Service
provider
Service
object
A client requests a service from
service attributes, and a copy of the
service object moves to the client
Middleware in MANET (KRNET2004)
Salutation: a Network independent architecture
z An architecture for service discovery
z Salutation consortium (IBM, HP, Sun, Cisco, ..)
▬ Goal : build a royalty-free architecture for service & discovery
that is independent of a particular network transport.
z Services
▬ Printing, faxing, document storage,..
z Salutation manager
▬ Service broker
▬ helps clients finds needed service & let services registers their
availability. It role similar to lookup servers in Jini, it can also
manager the connection between clients and services.
z Transport manager
▬ provides reliable communication channels, regardless of the
underlying network transport.
Middleware in MANET (KRNET2004)
Salutation Operation
Service
Service
slmRegisterCapabilityes()
Service
slmUnregisterCapabilityes()
Client
query
Client
slmSeaechCapabilityes()
Salutation
manager protocol
SLM-API
SLM-API
Salutation manager
Salutation manager
RPC (remote
procedure call)
SLM-TI
SLM-TI
Transport manager
Implementation
: IP & IrDA
Transport manager
z Provides a transport-independent interface to server and client
application. This interface (SLM-API) includes service registration,
service discovery and service access function.
z SLM-TI between the Salutation manager and Transport manager
achieves communication protocol independence in the Salutation
architecture
Middleware in MANET (KRNET2004)
UPnP
z Supported by the UPnP Forum, headed Microsoft.
z UPnP aims to standardize the protocols used by devices
to communicate using XML.
z UPnP’s device model is hierarchical.
Discovery
Server
Control point
(Client)
Application
command
Rehydrator
Presentation
Server
Service
The discovery server sends the
URL for the device’s description
document in response to the
client’s multicast message
The control point generates
the service control protocol
from information in the
description document
SCP
Middleware in MANET (KRNET2004)
UPnP Stack
UPnP Vendor
UPnP Forum
UPnP device architecture
HTTPMU
HTTPU (unicast)
SSDP
GENA
SSDP
UDP
HTTP
SOAP
GENA
HTTP
TCP
IP
GENA : General Event Notification Architecture
SOAP : Simple Object Access Protocol
SSDP : Simple Service Discovery Protocol
UDPs : User Datagram packets
Middleware in MANET (KRNET2004)
UPnP Service Discovery
z UPnP Service Discovery
▬ Use SSDP (Simple Service Discovery Protocol)
▬ Î HTTP over multicast (HTTPMU) and Unicast UDP (HYYPU)
z Using XML to describe device feature and capabilities.
z SOAP(simple object access protocol) object and URL in
XML format
z Automatic configuration of IP
Middleware in MANET (KRNET2004)
JXTA
z JXTA is a platform for developing a P2P network.
z JXTA Virtual Network
Middleware in MANET (KRNET2004)
JXTA Protocol Stack
Middleware in MANET (KRNET2004)
JXTA v2.0 Protocols Specification
z http://www.jxta.org
z http://spec.jxta.org/v1.0/docbook/JXTAProtocols.html
▬ The name is short for juxtapose (tr. v.To place side by side, especially for
comparison or contrast )
▬ peer to peer is juxtapose to client server or Web based computing
z Defines a suite of six XML-based protocols that standardize the manner in
which peers self-organize into peergroups, publish and discover peer
resources, communicate, and monitor each other.
z The Endpoint Routing Protocol (ERP)
▬ the protocol by which a peer can discover a route (sequence of hops) to send a
message to another peer potentially traversing firewalls and NATs.
z The Rendezvous Protocol (RVP)
▬ used for propagating a message within a peergroup.
z The Peer Resolver Protocol (PRP)
▬ the protocol used to send a generic query to one or more peers, and receive a
response (or multiple responses) to the query.
z The Peer Discovery Protocol (PDP)
▬ used to publish and discover resource advertisements.
z The Peer Information Protocol (PIP)
▬ the protocol by which a peer may obtain status information about another peers.
z The Pipe Binding Protocol (PBP)
▬ the protocol by which a peer can establish a virtual communication channel or
pipe between one or more peers.
Middleware in MANET (KRNET2004)
JXTA Advertisement and Discovery
z JXTA Advertisement
▬ An advertisement is a structured representation of a JXTA entity
(peer, peer-group, endpoint, message, pipe), service, or
resource on a node
▬ Example of advertisement for a resource:
{Type: resource, resource-name: mysong.mp3, resource-type: mp3audio, resource-location: someaddr, resource-file-size: 3.2MB}
▬ The response to a resource query in a JXTA P2P network is one
or more advertisements
▬ All user-level JXTA messages are advertisements
z JXTA supports three types of node discovery
▬
▬
▬
▬
No discovery
Direct discovery
Indirect discovery
(Last two are together called active discovery protocols)
Middleware in MANET (KRNET2004)
JXTA No Discovery Protocol
z Newly joined node does not send out ping
advertisement
z Newly joined node only accesses a cache (similar to a
lookup service) to get addresses of existing nodes
z Napster uses this protocol
Address Server
(contains advertisements with
addresses of existing nodes)
1.
Send an advertisement
requesting addresses of
existing nodes
2.
Respond with
advertisements of
addresses from
existing nodes
Newly joining node
Middleware in MANET (KRNET2004)
JXTA No Discovery Protocol Issues
z Advantages
▬ Simple
▬ Creates less traffic since there is no flooding
z Disadvantages
▬ Addresses-advertisements returned by address server might be stale
(The nodes that earlier made those advertisements might have already
left the network)
▬ Solution: Cache uses an aging mechanism for address-advertisements.
Old advertisements are expired.
▬ Aging schemes: tag with expiry date, FIFO stack
Middleware in MANET (KRNET2004)
JXTA Active Discovery Protocols
z Direct Discovery
▬ Same protocol as on slide 3
▬ Decrement a time-to-live (TTL) field on ping advertisement to prevent
loops
▬ Does not work across firewalls
z Indirect Discovery
▬ Same protocol as on slide 3
▬ Uses rendezvous/router peer to discover nodes outside firewall
▬ How does a new node find a rendezvous/router peer? Answer: Use
cache (address server).
Middleware in MANET (KRNET2004)
JXTA for Wireless Networks
z JXTA for J2ME™
▬ Extending the Reach of Wireless With JXTA Technology
▬ http://www.jxta.org/project/www/docs/JXTA4J2ME.pdf
▬ http://www.jxta.org/docs/jxta-dht.pdf
▬ Design Goals
¾
¾
¾
¾
¾
¾
. Be interoperable with JXTA on desktops and workstations
. Provide a P2P infrastructure for small devices
. Be simple and easy to use by developers
. Be small enough to be used with cellular phones and PDAs
. Allow the creation of applications that provide a good user experience
. Be MIDP-1.0 compliant
▬ JXTA for J2ME peers can only act as edge peers.
▬ Introduce JXTA Relay (Proxy relay)
Middleware in MANET (KRNET2004)
Proem: Mobile Peer-to-Peer Platform
z Peer-to-Peer Computing
▬ Any relationship in which multiple, autonomous hosts interact as equals
▬ Characteristics of Wired Peer-to-Peer Environment
¾ Ease of interconnection, Expansion of bandwidth, Wealth of cycles
¾ Æ Napster(, Gnutella(Decentralized Peer-to-Peer Search), Freenet, Groove
▬ Characteristics of Mobile Peer-to-Peer Environment
¾ Opposite to the wired case
¾ Æ Proem
z Proem
▬
▬
▬
▬
▬
http://www.cs.uoregon.edu/research/wearables/Papers/p2p2001.pdf
Use the decentralized search like Gnutella
Focuses on collaboration of peers (like mobile groupware)
Designed for highly dynamic environments of MANET
Major Services
¾
¾
¾
¾
¾
Presence manager (peer discovery)
Dataspace manager (Persistent storage of data spaces)
Community manager (peer’s membership management)
Peer database
Event bus
Middleware in MANET (KRNET2004)
Service Discovery in MANET
Middleware in MANET (KRNET2004)
Requirement of Middleware in MANET
Decentralized approach
Lightweight for implementation
Minimize the flooding of the service request message
Obtain service location information using passive
approach & active approach
z Fast turn around time for service reply massage
z
z
z
z
Middleware in MANET (KRNET2004)
Caching Mechansim Approach
z S. Motegi et. al.,“Service Discovery for Wireless Ad Hoc Networks,” The 5th International
Symposium on Wireless Personal Multimedia Communications, 2002
z Multi hop wireless MANET : infrastructureless (no fixed
routers, nodes & base stations)
z Service discovery method
▬ Service Location Protocol (SLP), Salutation, and Jini : fixed
infrastructure network
▬ Use centralized nodes that store configuration information (IP
address, URL, attributes etc.) of the services. : centralized approach
z Service discovery in MANET
▬ decentralized approach
▬ client broadcast/multicast : expensive process
▬ Minimize spreading of broadcast messages (service request msg,
service reply msg) by using a caching mechanism
z Caching mechanism
▬ Intermediate nodes respond with configuration information on
services from cache.
▬ Do not rebroadcast the request messages.
▬ Potential drawback : lowering the number of discoverable services
Middleware in MANET (KRNET2004)
Caching Mechanism Approach II
z Reduced SrvRqst
z Intermediate nodes respond with a SrvRply
z Disadvantage: Lowering the number of discoverable services
(11) SrvrRqst S1 Cache
Cache
(12) Srvrply S1
S1
(3)
S1
(8)
(6)
(3)
C2
N1
(4)
N2
(7)
(1)
S1
(5)
(9)
SrvRqst
(1)
C1
S2
SrvRply
(2)
C2 can not discover S2 because C2 received SrvRply which
contains just one configuration of S1.
Middleware in MANET (KRNET2004)
Using Multicast for Service Advertisement
z L. Cheng, Workshop on Ad Hoc communications and collaboration
in ubiquitous computing environments, ACM 2002 conference, New
Orleans, USA, November 16-20, 2002
z Lightweight service advertisement and
discovery protocol for MANET
z Based on ODMRP (On-demand Multicast
Routing Protocol)
z Service advertisement & discovery information
is piggybacked ODMRP routing control packets.
z Bootstrapping mechanism (push model)
z Query/reply mechanism (pull model)
Middleware in MANET (KRNET2004)
Service Discovery in MANET
z Multicast is used for service discovery in MANET.
▬ Broadcast nature of wireless communication environment
▬ Infrastructureless feature of MANET
▬ One-to-many character of service advertisement & discovery
z Multicast protocol for MANET
▬ AMRoute (Ad Hoc multicast routing)
▬ ODMRP (On-Demand Multicast routing protocol)
▬ Î very effective and efficient in most simulation scenarios
compare to other
▬ AMRIS (Ad Hoc multicast protocol utilizing increasing idnumbers)
▬ CAMP (core-assisted mesh protocol)
▬ flooding
Middleware in MANET (KRNET2004)
Service Location Protocol Overhead in the Random Graph
Model for Ad Hoc Networks
z Hend Koubaa, Eric Fleury, Proceedings of the Seventh international
Symposium on computers and communications (ISCC’02)
z Mediator Approach
▬ MANET can be viewed as a set of cluster.
▬ Mediator must allow services to be declared without having
recourse to broadcast and must allow a client to search for
services in their local area.
▬ Provider : a cluster-head of its cluster, each provider
periodically declares its identity and its services to all its
neighbors.
▬ Problem : election Mediator & provider, traffic concentration to
the Mediator
Middleware in MANET (KRNET2004)
Mediator Approach
M1
P1
M3, P5
P2
M2
P4
M4,P6
M5
Mediator
Provider
Middleware in MANET (KRNET2004)
P3
Requirement of SLP on MANET
z
z
z
z
Decentralized approach
Lightweight for implementation
Minimized flooding the service request message
Obtained service location information using passive approach &
active approach
z Fasted turn around time for service reply massage
Î Consist of only SA and UA, DA is no need
Î SA broadcast its service information within n hop
Î Every mobile node caching the SA’s service information
Middleware in MANET (KRNET2004)
SLP on MANET
Registered
RegisteredSA
SAlist
list
DA
DA(Directory
(Directory
Agent)
Agent)
(2) Finding
a service
(1) Service registration
(3) Response
(URL)
UA
UA(User
(User
Agent)
Agent)
(4) Request
service
SA
SA(Service
(Service
Agent)
Agent)
Printer
Middleware in MANET (KRNET2004)
Proposed Service Discovery Architecture
zH.G. Seo and K.H. Kim, “Mobility Agent Advertisement
Mechanism for Supporting Mobile IP in Ad Hoc Networks”,
LNCS (to be published)
DA
Sports News
service
Service
register
Local network
(2-3) Service
Print
service
Co_workin
g
Service
register
MDA
(1-1)VOD Service
request
(2-1)Print Service
request
(1-2) Service reply
(1-3)
Service
UA
1
VOD
service
Servic
e
registe
r
GIS
service
Middleware in MANET (KRNET2004)
(2-2)Service reply
UA
2
원하는 서비스가 같은 MANET 에 있을 경우 경로 생성 과정
DHCP
DA
MSA4
Local network
MDA
MSA3
(1)SrvRqst : VOD
service
(2)SrvRply : MSA2
MN1
(3)Route request
to MSA2
MN2
MN3
MN4
MSA1
MP3
service
MN5
MN6
MSA2 VOD service
MN7
Middleware in MANET (KRNET2004)
(4)Route reply &
route establishment
원하는 서비스가 다른 외부 네트워크에 있을 경우
DHCP
DA
MSA4
Local network
(2)SrvRqst :co_working
(4)Route establishment
MDA
MSA3
Print service
(1)SrvRqst : print service
MN1
(3)SrvRplyMN2
MN3
MN4
MSA1
MP3
service
MN5
MN6
MSA2
MN7
Middleware in MANET (KRNET2004)
Conclusions
z Survey of existing service discovery protocols
•
•
•
•
•
•
Blutooth SDP
SLP (IETF RFC2608)
Jini (http://www.jini.org )
Salutation (http://www.salutation.org )
UPnP (http://www.upnp.org )
JXTA
z Service advertisement and discovery mechanisms in Ad
Hoc networks
z Proposed service discovery mechanism in MANET
Middleware in MANET (KRNET2004)
References
z
z
z
z
z
z
z
z
z
z
z
z
z
z
z
z
T.Plagemann et al., “Towards Middleware Services for Mobile Ad-hoc Network Applications,”
Proceedings of the Ninth IEEE Workshop on Future Trends of Distributed Computing
Systems(FTDCS’03)
M. Avvenuti et al., “Core Services in a Middleware for Mobile Ad Hoc Networks, FTDCS’03
M. Dyrna, Peer2peer Network Service Discovery for Ad-hoc Networks Hauptseminar im Wintersemester
2003 / 2004
http://www.jxta.org
http://spec.jxta.org/v1.0/docbook/JXTAProtocols.html
http://www.jxta.org/project/www/docs/JXTA4J2ME.pdf
M. Bisignano et al., Expeerience: a Jxta middleware for mobile ad-hoc networks, Proceedings of the
Third International Conference on Peer-to-Peer Computing (P2P’03)
P. Engelstad et al., Service Discovery and Name Resolution Architectures for On-Demand MANETs,
23rd International Conference on Distributed Computing Systems Workshops (ICDCSW'03) May 19 - 22,
2003 Providence, Rhode Island, USA
http://www.jxta.org/docs/jxta-dht.pdf
http://www.cs.uoregon.edu/research/wearables/Papers/p2p2001.pdf
G. Guichal and C-K Toh, An Evaluation of Centralized and Distributed Service Location Protocols for
Pervasive Wireless Networks, “
Guichal, G.; Toh, C.-K., An evaluation of centralized and distributed service location protocols for
pervasive wireless networks, Personal, Indoor and Mobile Radio Communications, 2001 12th IEEE
International Symposium on , Volume: 2 , 30 Sept.-3 Oct. 2001, Pages:E-55 - E-61 vol.2
S. Motegi et al.,“Service Discovery for Wireless Ad Hoc Networks,” The 5th International Symposium on
Wireless Personal Multimedia Communications, 2002
L. Cheng, Service Advertisement and Discovery in Mobile Ad hoc Networks, Workshop on Ad Hoc
communications and collaboration in ubiquitous computing environments, ACM 2002 conference, New
Orleans, USA, November 16-20, 2002
Hend Koubaa and Eric Fleury, Service Location Protocol Overhead in the Random Graph Model for Ad
Hoc Networks, Proceedings of the Seventh international Symposium on computers and communications
(ISCC’02)
H.G. Seo and K.H. Kim, “Mobility Agent Advertisement Mechanism for Supporting Mobile IP in Ad Hoc
Networks”, LNCS (to be published)
Middleware in MANET (KRNET2004)