P2P for Collaborative Communities

Project supervisor: prof. Andrzej Duda [email protected]: Tomasz Bartyński [email protected] Eliasz [email protected]

P2P for Collaborative Communities

14 june 2007 Tomasz Bartynski Wojciech Eliasz p2p-voip LIG

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Agenda (1)

Project goalsRequirements for our systemState-of-the-art in file sharing and VOIP

protocols and programsBittorrent+Azureus and

SIP+jabber+SipCommunicator as starting points for our project


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Agenda (2)

Our concept of the systemFuture workWork doneReferences


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Project goals

Support E-Learning by providing user with means to:Share Learning Objects in a P2P

environmentDescribe and search LOsCreate communities interested in one

specific domainCommunicate within the community


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Requirements (1)

Use standard, reliable protocols and technologies

Portability (Windows/Linux/Mac Os)Open sourceRemain compatible with standard

clients


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Requirements (2)

Privacy and security (ability to work in Virtual Private Network established by Hamachi)

No spyware/addwareLegal issuesSpeed of file transfers is not crucial

(size of Learning Objects files are expected to be relatively small)


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P2P File Sharing

Nodes (peers) are equal and act both as a client and a server

Networks are established ad hocP2P networks compared to client-server

modelEnable better resource utilizationProvide higher reliabilityReduce the cost of bandwidth and hardware


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State of the art in FS protocols

Most popular protocolsBittorentE-DonkeyFastTrackMany others (please refer to project

documentation)


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Bittorent protocol

- .torrent (includes meta data about content and tracker address)

•Enables distribution of large amounts of data

•Reduces hardware, hosting and bandwidth expenses

•Eliminates single point of failure


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State of the art in FS programmes

Bittorent E-Donkey FastTrack

Azureus E-Donkey 2000

Kazaa

Bittorent E-Mule Kazaa Lite

BitCommet A-Mule giFT

File sharing programs


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Azureus

Implemented in Java and published under GNU General Public License

Cross-platform One of the most popular Bittorent client Can be easily extended by adding plugins


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SIP (1)

Application-layer control (signaling) protocol for creating,modifying, and terminating sessions with one or more participants.These sessions include Internet telephone calls, multimedia distribution, and multimedia conferences.

Signaling protocol just like H.225, H.245 and RTSP Open standard designed by IETF and described in

several RFCs SIP doesn’t work alone, Session Description Protocol

is used to describe session information and RTP/RTCP protocols are used for media transfer


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SIP (2)

Messages are delivered in plain text with syntax similar to HTTP and SMTP

Sip user identifier is similar to e-mail address e.g. sip:[email protected]

Phone number format is also possible e.g. sip:+48126178350

SIP is able to localize users, verify users presence, check users terminal parameters, creation of sessions and modification of sessions


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SIP architecture

UA – User Agent – represents end user Redirect Server – maps addresses to other addresses, redirects clients to

different locations Proxy - intermediate element redirects requests, can modify SIP messages Registar Server – stores register messages from clients , maps sip identifiers to

physical addresses Location Server – used to find current location of user, used by redirect servers

and proxies


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P2P-SIP

P2P approach reduces need for centralized servers

Approach suitable for small organizations without internet connection

SIPpeer acts as a SIP User Agent, proxy and registar server

Information is shared between peers using Distributed Hash Table


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- XMPP (1)

An open, XML-based protocol for near-real-time, extensible instant messaging (IM) and presence information

Based on open standards, developed by IETF

Users have identifiers similar to mail addresses


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- XMMP (2)

IETF defined set of extensions - XEPs (XMPP Extension Protocol) to standard funcionality

Jingle – p2p signaling protocol for multimedia interactions designed by Google and XMPP Standards Foundation

libjingle used by GoogleTalk has been released to public


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State of the art in messengers

Name Licence Protocol EncryptionBitWise IM Proprietary

freeware / Closed commercial

Propertiary protocol Blowfish

Gizmo Proprietary freeware SIP, XMPP, Jabber SRTP

Google Talk Proprietary freeware (libjingle is Free software

XMPP, Jabber

Lotus Sametime Closed commercial SIP, SIMPLE, H.323

OpenH323 MPL free software H.323

SIP Communicator LGPL free software SIP/SIMPLE, Jabber

Zoiper Freeware + commercial

SIP, RTP, STUN, IAX, IAX2

* This compilation contains only solutions fulfilling our previously mentioned requirements


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SIP-Communicator

SIP Communicator is an open source (LGPL) Audio/Video software phone and instant messenger. Among SIP Communicator is completely Open Source / Free Software, and is freely available under the terms of the GNU Lesser General Public License.

The SIP Communicator was originally created by Emil Ivov who was at the time a student at the Louis Pasteur University in Strasbourg, France

Google Summer of Code 2007 participants are developing new features of SIP-Communicator


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SIP-Communicator: features

Audio and Video calls with SIP Instant Messaging with Jabber, ICQ/AIM,

Yahoo! Msngr and MSN IPv6 support for SIP and Jabber Support for multiple accounts and meta

contacts Basic NAT & Firewall Traversal with STUN Modularity, extensibility and flexibility with

OSGi Platform specific installers for Windows,

Debian, Fedora and Mac OS X


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SIP-Communicator: used technologies

Apache Felix - an OSGI implementation by Apache growl - A Mac OS X notification daemon. jain-sip - SIP protocol stack java-jml - An implementation of the MSN protocol dnsjava - An implementation of DNS for Java jspeex - A java implementation of the speex audio

codec. jYMSG - YMSG Java API - Yahoo Instant Messenger

Support for Java. smack - An open source jabber stack for Java by Jive

Software. stun4j - An implementation of the STUN


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SIP-Communicator: design


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Our concept of the system (1)

Integrate Azureus with SIP-Communicator


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Our concept of the system (2)

LOs are distributed in P2P network with Azureus Azureus provides information about peers sharing

learning object SIP and Jabber communication is performed using

Sip-communicator Special protocol is implemented to provide sip and

jabber contacts distribution between peers Contacts are stored in Sip-Communicator Connection between Azureus and Sip-Communicator

is managed by special facade implemented as OSGi bundle


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Possible solutions (1)

1. Modify peer id

2. Include tracker jabber and SIP addresses in .torrent metafile

3. Modify HTTP request to include communication addresses

4. Modify peers handshake

5. Obtain communication IDs from communicator and send it to all peers downloading specific Learning Object


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Peer ID20-byte string Azureus uses:'-', two characters for client

id, four ascii digits for version number, '-', followed by random numbers

Nor Jabber ID nor SIP address can included


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Include communication addresses in metafile Implemented as an additional property While publishing new content addresses of

the publisher are added to .torrent fileRemains compatible with standard client

(additional entry in dictionary will be omitted)


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Modify http requestRequest are processed by external trackers,

embedded trackers and peersDifficult to implementRequires modifications in various parts of

Azureus


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Modify peers handshakeThe handshake is a required message and

must be the first message transmitted by the client.

Handshake has a fixed size and syntax: <pstrlen><pstr><reserved><info_hash><peer_id> and can not be changed


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Obtain communication IDs from communicator and send it to all peers downloading specific Learning ObjectXEP-0093 or XEP-0144Our implementation of contacts exchange


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Prototype implementation

Integration of Azureus and SIP-Communicator


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Enhancements

Include version information in peer idConsider various policies of distributing

contactsCompose SIP-Communicator into

Azureus view


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Difficulties encountered

Azureus code being underdevelopment Version 3.0 uses core of version 2.5 Version 2.5 tries to create GUI of version 3.0 Version 3.0 was not released for Linux platform

SIP-Communicator combined with Azureus constitutes a project with over 3,400 source files

Technical documentation of Azureus code is not published


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Difficulties encountered (2)

Azureus has many authors who use different programming practices

SIP-Communicator is build upon OSGI framework and Azureus not

Programs use different GUI libraries (Swing and SWT)


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Difficulties encountered (3)

Sip-Communicator is still in alpha version, and has a lot of bugs

OSGi has sophisticated class loader system which makes maintenance of bundles relationships time consuming and error prone


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Future work (1)

Use ontologies to describe and search Learning Objects

Create a classification of scientific domains, Learning Objects, authors etc.

Starting pointOWL (Web Ontology Language) is a good

candidate to be usedProtégéRacer reasoning engine


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Future work (2)

•Ontology provide domain taxonomy

•Authors and LO can be described with properties and relationships


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Work done

State of the art in FS and VOIPAzureus and SIP-Communicator

investigationImplementationResearch and ideas for enriching project

with ontologies


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References

Azureus home page http://azureus.sourceforge.net/

Bittorrent http://en.wikipedia.org/wiki/BitTorrent SIP-Communicator

http://www.sip-communicator.org/ SIP

http://en.wikipedia.org/wiki/Session_Initiation_Protocol

Jabber http://www.jabber.org/ Please refer to project documentation for more

materials


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• Thank you for you attention

•Questions?

P2P for Collaborative Communities

Documents