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Client/Server Distributed SystemsClient/Server Distributed Systems

ObjectiveObjective– explain JXTA, a support environment for explain JXTA, a support environment for

P2P services and applicationsP2P services and applications

240-322, Semester 1, 2005-2006

15. JXTA (Juxtapose)

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ContentsContents

1.1. Principle AimsPrinciple Aims

2.2. JXTA Main ComponentsJXTA Main Components

3.3. JXTA ConceptsJXTA Concepts

4.4. Example Services and Apps.Example Services and Apps.

5.5. JXTA Compared to JiniJXTA Compared to Jini

6.6. More InformationMore Information

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1. Principle Aims1. Principle Aims

JXTA provides core functionality so that deJXTA provides core functionality so that developers can build P2Pvelopers can build P2P services and applicaservices and applications.tions.

JXTA can be implemented with any prograJXTA can be implemented with any programming language and run on any softwaremming language and run on any software aand hardware platform/device.nd hardware platform/device.

continued

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It can be implemented on top of TCP/IP, HTIt can be implemented on top of TCP/IP, HTTP, Bluetooth, and many other protocols.TP, Bluetooth, and many other protocols.

Currently requires a platform that supports thCurrently requires a platform that supports the JRE or JDK 1.3.1 or later.e JRE or JDK 1.3.1 or later.

Available on Windows, Solaris, Linux, and Available on Windows, Solaris, Linux, and Macintosh.Macintosh.

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2. JXTA2. JXTA Main Components Main Components

JXTA supports a three layer view of P2P deJXTA supports a three layer view of P2P development:velopment:

– a core layera core layer

– a middle services layera middle services layer

– an application layeran application layer

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DiagramDiagram

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2.1. The Core Layer2.1. The Core Layer

The core layer includes protocols and buildiThe core layer includes protocols and building blocks to enable key mechanisms for P2ng blocks to enable key mechanisms for P2P networkingP networking– these include discovery, transport (e.g. firewall these include discovery, transport (e.g. firewall

handling and limited security), and the creation handling and limited security), and the creation of peers and peer groupsof peers and peer groups

– the protocols use XML-encoded messagesthe protocols use XML-encoded messages

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2.2. The Services Layer2.2. The Services Layer

The services layer provides P2P services, toThe services layer provides P2P services, tools, and commands ols, and commands – e.g. searching, sharing and added securitye.g. searching, sharing and added security

– e.g. the JXTA Shell, the JXTA Search e.g. the JXTA Shell, the JXTA Search (see below)(see below)

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2.3. The Application Layer2.3. The Application Layer

The application layer supports the implemeThe application layer supports the implementation of integrated applicationsntation of integrated applications– e.g. file sharing, resource sharing, monetary syse.g. file sharing, resource sharing, monetary sys

tems, distributed storage tems, distributed storage – reimplementations of programs like Gnutella, Nreimplementations of programs like Gnutella, N

apster, Groove, Instantapster, Groove, Instant MessengerMessenger– e.g. InstantP2P (see below)e.g. InstantP2P (see below)

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3. JXTA Concepts3. JXTA Concepts

What is a Peer?What is a Peer? What are Peer Groups?What are Peer Groups? JXTA PipesJXTA Pipes Peer MonitoringPeer Monitoring The Main JXTA ProtocolsThe Main JXTA Protocols

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A JXTA SystemA JXTA System

peer group

monitor

join

leave

ask to join

or query group

dynamicpipes

peer groupcomms.

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3.1. What is a Peer?3.1. What is a Peer?

A peer is any device that runs some/all of the JXA peer is any device that runs some/all of the JXTA protocols.TA protocols.

The peer needs to be connected to some kind of The peer needs to be connected to some kind of network, such as IP, Bluetooth.network, such as IP, Bluetooth.

Peers can be servers, PCs, PDAs, manufacturing Peers can be servers, PCs, PDAs, manufacturing and medical equipment, and medical equipment, cellular phones, etc.cellular phones, etc.

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3.2. What are Peer Groups?3.2. What are Peer Groups?

A peer group is a collection of peers that have aA peer group is a collection of peers that have agreed upon a common set of rules to publish, shgreed upon a common set of rules to publish, share and access their data, and communicate betare and access their data, and communicate between themselves. ween themselves.

Each peer group can establish its own membersEach peer group can establish its own membership policyhip policy– e.g. from open (anybody can join) to highly secure e.g. from open (anybody can join) to highly secure

and protectedand protected

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3.3. JXTA pipes3.3. JXTA pipes

JXTA pipes are inter-peer communication cJXTA pipes are inter-peer communication channelshannels– similar to the UNIX idea of piping the output of similar to the UNIX idea of piping the output of

oneone command to the input of another command to the input of another

Pipes are unidirectional and mayPipes are unidirectional and may be dynamibe dynamically coupled and uncoupled for flexible cocally coupled and uncoupled for flexible connection ofnnection of peers. peers.

continued

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Piped messages are XML documents and so Piped messages are XML documents and so are platform, language, and protocolare platform, language, and protocol indepeindependent.ndent.

The contents of messages can be binary codThe contents of messages can be binary code, data strings, Java technology-based objece, data strings, Java technology-based objects, and/or applets. ts, and/or applets.

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3.4. Peer Monitoring3.4. Peer Monitoring

Peer monitoring is the Peer monitoring is the policemanpoliceman of the of the corecore– handles authentication/authorization, meterhandles authentication/authorization, meter

ing, etc.ing, etc.

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3.5. The Main JXTA Protocols3.5. The Main JXTA Protocols

NetPeerGroup ProtocolNetPeerGroup Protocol Peer/PeerGroup Discovery ProtocolPeer/PeerGroup Discovery Protocol Peer Information and Management ProtocolPeer Information and Management Protocol PeerGroup Membership ProtocolPeerGroup Membership Protocol PeerGroup Resolver ProtocolPeerGroup Resolver Protocol

– send and receive generic queries to find or search for pesend and receive generic queries to find or search for peers,ers, peer groups, pipes, and other information.peer groups, pipes, and other information.

PeerGroup Sharing ProtocolPeerGroup Sharing Protocol

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4. Example Services and Apps.4. Example Services and Apps.

Service examples:Service examples:– JXTA ShellJXTA Shell– JXTA SearchJXTA Search

Application:Application:– InstantP2PInstantP2P

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4.1. JXTA Shell4.1. JXTA Shell Enables users to interact with the JXTA core thrEnables users to interact with the JXTA core thr

ough a command-line interpreter. ough a command-line interpreter.

Useful for:Useful for:– accessing and managing core platform objects (peersaccessing and managing core platform objects (peers

, groups, pipes), groups, pipes)– setting up pipessetting up pipes– debugging communicationsdebugging communications– checking the status of peers and/or peer groupschecking the status of peers and/or peer groups

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4.2. JXTA Search4.2. JXTA Search

Searches for content and services on JXTA Searches for content and services on JXTA nodes and the Web.nodes and the Web.

Uses a new XML search protocol for descriUses a new XML search protocol for describingbing queries and responses.queries and responses.

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4.3. InstantP2P4.3. InstantP2P InstantP2P implements a set of common P2P appInstantP2P implements a set of common P2P app

licationslications– includes peer-to-peer messaging (secure and plain teincludes peer-to-peer messaging (secure and plain te

xt), peer group chat, and file sharingxt), peer group chat, and file sharing

It provides a simple graphical user interface to crIt provides a simple graphical user interface to create and join groups.eate and join groups.

The source code is available.The source code is available.

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5. JXTA Compared to Jini5. JXTA Compared to Jini

JiniJini connects distributed services within a J connects distributed services within a Java network using an object model and a ceava network using an object model and a centralized service location broker. ntralized service location broker.

JXTA connects distributed services in a P2PJXTA connects distributed services in a P2P-style network,-style network, using a loosely-coupled data using a loosely-coupled data model.model.

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A Jini SystemA Jini System

locationbroker

printer

databasedynamicnetworkof services

mobiledevice

1.enquire

2. report

3. connect

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6. More Information6. More Information

Project JXTAProject JXTA– http://www.jxta.orghttp://www.jxta.org

– JXTA software, documents, etc.JXTA software, documents, etc.