Sistem Terdistribusi Peer to Peer Systems
Client Server vs P2P • Client/server is hierarchical system, with resources centralized on a limited number of servers. • In peer-to-peer networks, both resources and control are widely distributed among nodes that are theoretically equals. – A node with more information, better information, or more power may be “more equal,” but that is a function of the node, not the network controllers.
The architectures • Server-based architecture – Client-Server / Server-Cluster – Problems： • Limited resources • All loads are centered on the server
– Server-based architecture has low scalability. – The setup and maintenance cost is high.
• Peer-to-Peer (P2P) architecture – Advantages： • Distributing loads to all users • Users consume and provide resources
– P2P architecture has high scalability. – The setup and maintenance cost is low.
The Client Side • Today’s clients can perform more roles than just forwarding users requests • Today’s clients have: – more computing power – more storage space
• As the Internet usage grow, more and more PCs are connecting to the global net • Most of the time PCs are idle • Thin client Fat client
Decentralization • A key feature of peer-to-peer networks is decentralization. • This has many implications: – robustness: handal – availability of information: selalu ada & tersebar dimasing2 client – fault-tolerance tends to come from redundancy => satu down yg lain bisa handle – and shared responsibility: tugas dibagi
Technology Transition
The Client/Server Model
The Peer-to-Peer Model
Peer to Peer (P2P) - Setiap komputer yang terhubung ke jaringan dapat bertindak baik sebagai client maupun server. - Server di jaringan tipe peer to peer disebut nondedicated server - karena server tidak berperan sebagai server murni, tetapi sekaligus dapat berperan sebagai client.
- Pada jaringan tipe ini semua komputer berkedudukan sama, dapat bertindak sebagai sebuah PC client (information requestor) maupun PC server (information provider).
Jenis P2P: Pure P2P Masing-masing peer berstatus setara (egaliter), setiap peer berstatus sebagai client juga server. Tidak ada server pusat yang mengatur jaringan. Tidak ada router yang menjadi pusat jaringan. Bisa terdiri dari > 2 komputer
Hybrid P2P - Mempunyai server pusat yang memantau dan menjaga informasi yang berada di setiap peer sekaligus merespon peer ketika ada yang meminta informasi tertentu. - Setiap peer bertanggung jawab untuk menyediakan resource yang tersedia. -
Karena server pusat tidak memiliki resource tersebut, hal ini juga dilakukan agar server pusat tersebut dapat mengetahui resource apa saja yang akan didistribusikan di dalam jaringan.
Why P2P? • Information - Hard to find, impossible to catalog and index all of the information • Bandwidth - Hot links get hotter – Makin bagus informasi, makin laris dan makin tak terbendung – Makin banyak juga yg “memilikinya” dan tersebar dimana-mana
• Computing resources - Heavily loaded nodes get overloaded, idle nodes remain idle
P2P Goals/Benefits • Cost/data sharing • Reduce cost: operasional murah • Resource aggregation (digabungkan) dari berbagai sumber • Improved reliability : kerja jaringan tidak tergantung pada satu server • Increased autonomy (kebebasan) pada masing-masing peer • Anonymity/privacy masing2 peer • Scalability : since every peer is alike, it is possible to add more peers to the system and scale to larger networks.
P2P Computing Applications • File sharing – Improves data availability – E.g., Napster, Gnutella, Freenet, KaZaA
• Process sharing – For large-scale computations – Data analysis, data mining, scientific computing – E.g.: SETI@Home, Folding@Home, distributed.net
• Collaborative environments – For remote real-time human collaboration. – Instant messaging, virtual meetings, shared whiteboards, teleconferencing, tele-presence. – E.g.: talk, IRC, ICQ, AOL Messenger, Jabber, MS Netmeeting, NCSA Habanero, some of Games
SETI@Home • SETI – Search for Extra-Terrestrial Intelligence • @Home – On your own computer • A radio telescope in Puerto Rico that scans the sky for radio signals • Its purpose is to analyze radio signals, searching for signs of extra terrestrial intelligence, and is one of many activities undertaken as part of SETI • to prove the practicality of the 'volunteer computing' concept. • Fills a DAT tape of 35GB in 15 hours • That data have to be analyzed (very large computing)
SETI@Home - Example
Kelemahan Peer to Peer (P2P) Troubleshooting jaringan relatif lebih sulit, karena pada jaringan tipe peer to peer setiap komputer dimungkinkan untuk terlibat dalam komunikasi yang ada. Di jaringan client-server, komunikasi adalah antara server dengan workstation.
Unjuk kerja lebih rendah dibandingkan dengan jaringan client-server, karena setiap komputer/peer disamping harus mengelola pemakaian fasilitas jaringan juga harus mengelola pekerjaan atau aplikasi sendiri.
Kelemahan Peer to Peer (P2P) Sistem keamanan jaringan ditentukan oleh masing-masing user dengan mengatur keamanan masing-masing fasilitas yang dimiliki. Karena data jaringan tersebar di masingmasing komputer dalam jaringan, maka backup harus dilakukan oleh masingmasing komputer tersebut.
Kelemahan P2P • Decentralized coordination – How to keep global state consistent? – Need for distributed coherency protocols.
• All nodes are not created equal. – Computing power, bandwidth have an impact on overall performance.
Dangers and Attacks on P2P • • • • • • • • •
Poisoning (files with contents different to its description) Polluting (inserting bad packets into the files) Defection (users use the service without sharing) Insertion of viruses (attached to other files) Malware (spy originally attached to the files) Denial of Service (slow down or stop the network traffic) Filtering (some networks don’t allow P2P traffic) Identity attacks (tracking down users and disturbing them) Spam (sending unsolicited information)
P2P Technical Challenges • • • • • • • •
Peer identification Routing protocols Network topologies Peer discovery Communication/coordination protocols Quality of service Security Resource management
P2P Topologies Centralized Ring
Hierarchical
Decentralized
Hybrid
Centralized
Hieralchical
Ring
Decentralized
Hybrid
EXAMPLE P2P Centralized Napster P2P Decentralized KaZaA P2P Hybrid JXTA
Napster • The first large scale peer-to-peer network was Napster, set up in 1999 to share digital music files over the Internet. • While Napster maintained centralized (and replicated) index, the music files were created and made available by individuals, usually with music copied from CDs to computer files. • Music content owners sued Napster for copyright violations and succeeded in shutting down the service.
Napster: a centralized, replicated index peers
Napster server Index 1. File location request 2. List of peers offering the file
Napster server Index 3. File request
5. Index update 4. File delivered
Napster Sharing Style Title song1.mp3 song2.mp3 song3.mp3 song4.mp3 song5.mp3 song5.mp3 song6.mp3 song6.mp3 song7.mp3
1. Users launch Napster and connect to Napster server 2. Napster creates dynamic directory from users’ personal .mp3 libraries 3.
beastieboy
User beasiteboy beasiteboy beasiteboy kingrook kingrook slashdot kingrook slashdot slashdot
Speed DSL DSL DSL T1 T1 28.8 T1 28.8 28.8
enters search criteria
s ong5
4. Napster displays matches to beastieboy 5.
makes direct connection to kingrook for file transfer
beastieboy
“beastieboy”
“kingrook”
“slashdot”
•song1.mp3 •song2.mp3 •song3.mp3 •song5.mp3
•song4.mp3 •song5.mp3 •song6.mp3
•song5.mp3 •song6.mp3 •song7.mp3
Napster: Lessons Learned • Napster created a network of millions of people, with thousands of files being transferred at the same time. • There were quality issues. While Napster displayed link speeds to allow users to choose faster downloads, the fidelity of recordings varied widely. • Since Napster users were parasites of the recording companies, there was some central control over selection of music. • There was no guarantee of availability for a particular item of music.
P2P legal controversy • P2P structure and functionalities make it perfect for sharing vast ammounts of files • Unfortunately, people use it fo illegal downloading • Recording Industry Association of America introduces lawsuits and seeks legal changes – CDs, mp3 players introduce restrictions and become more expensive
27
Legal Facts from RIAA • “Music piracy is any form of unauthorized duplication and/or distribution of music including downloading, file sharing, and CD-burning.” • “Criminal penalties can be as high as five years in prison or $250,000 in fines.” • RIAA wants to find violators of copyright law
Morpheus: Free Anonymizer • Another file-sharing application • In 2003 Streamcast Networks (owners) included a free Anonymizer with Morpheus • Through proxies, users don’t see each other • Also includes blacklist of data ‘snooping’ • iMesh (Israel) and Blubster (Spain) among others now provide the same service
The ‘Animal’ GNU GNU: Recursive Acronym GNU’s Not Unix ….
GNU
Gnutella =
+
Nutella
Nutella: a hazelnut chocolate spread produced by the Italian confectioner Ferrero ….
Gnutella History • Gnutella was written by Justin Frankel, the 21-year-old founder of Nullsoft. • Nullsoft acquired by AOL, June 1999 • Nullsoft (the maker of WinAmp) posted Gnutella on the Web, March 14, 2000. • 23k users on Gnutella • People had already downloaded and shared the program. • Gnutella continues today, run by independent programmers.
Gnutella Protocol Scenario: Joining Gnutella Network • • • • • • • •
•
ping: discover hosts on network Gnutella Network pong: reply to ping query: search for a file query New PING hit: reply to query push: download request PING PONG The new node connects to a well known PING ‘Anchor’ node or ‘Bootstrap’ node. A Then sends a PING message to discover other nodes. PING PONG messages are sent in reply from PING hosts offering new connections with the new node. PING Direct connections are then made to the newly discovered nodes.
PONG
Gnutella: Issue a Request
xyz.mp3 ?
Gnutella: Flood the Request
Gnutella: Reply with the File Fully distributed storage and directory!
P2P is using Hasing
Object ID (key):AABBCC Shark
SHA-1 Object ID (key):DE11AC SHA-1
194.90.1.5:8080
Hashing Basic Idea Publish (H(y))
P2P Network
Object “y” Objects have hash keys
Join (H(x))
Peer “x” H(y)
H(x)
y Hash key
Peer nodes also x have hash keys
in the same hash space
Place object to the peer with closest hash keys
Viewed as a Distributed Hash Table Hash table
2128-1
0
Peer node
Internet
How to Find an Object? Hash table Peer node
0
2128-1
Chord Lookup – with finger table I’m node 2. Please find key 14!
15
1
14
Start
Int.
node
2+1
[3,4)
3
2+2
[4,6)
7
2+4
[6,10)
7
2+8
[10,2)
10
2
14 ∈[10,2) 3
12 Start
Int.
node
10+1
[11,12)
12
10+2
[12,14)
12
10
10+4
[14,2)
14
14 ∈[14,2)
10+8 40/46
[2,10)
2
Circular 4-bit ID space 7
JXTA • Website : https://jxta.dev.java.net/ • Dimotori oleh Bill Joy dari Sun Microsystem, didukung oleh komunitas dari kalangan akademis dan industri • JXTA dirancang untuk lebih baik dibanding solusi P2P yang sudah ada
JXTA • JXTA merupakan kependekan dari juxtapose, yang artinya mendekatkan/menghubungkan • Tujuan utama JXTA sebagai platform P2P yang : – Interoperability – Platform Independence – Ubiquity (seamless integration between devices)
JXTA • Interoperability – Setiap vendor dapat mengeluarkan protokol P2P sendiri yang tidak sama, namun tetap dapat terkoneksi
• Platform Independence – Dapat dijalankan di banyak platform, mendukung banyak bahasa pemrograman
• Ubiquity – Tidak hanya PC, mobile device juga bisa terhubung dalam jaringan P2P JXTA ini
JXTA Terms and Concepts • Peers : tiap-tiap node dalam JXTA • Advertisements – Dokumen XML terstruktur tentang informasi layanan/resource yang ada pada suatu peer
• Messages – Data yang dipertukarkan antar peer (XML atau binary)
• Pipes – Jalur yang digunakan untuk mengirim Message
• Identifiers – Identitas unik setiap peer (UUID Identifier)
• Rendezvous Nodes : – node yang dapat menerima dan mengeluarkan koneksi dari banyak node serta membetuk suatu group
• Relay Nodes – JXTA routers, untuk akses network dari belakang firewall, NAT
JXTA Architecture JXTA Applications
JXTA Services
JXTA Core
JXTA Community Applications
JXTA Community Services
Peer Groups
SUN JXTA Applications
JXTA Shell
SUN • Indexing Peer JXTA • Searching Commands Services • File Sharing Peer Pipes
Peer Monitoring
Security (authentication, authorization and on the wire) Any Peer on the extended Web
JXTA Virtual Network Peer
JXTA Virtual Network
Peer Peer
Peer
Peer
Peer
Peer Peer
Virtual Mapping Bluetooth Firewall
Http Firewall
Physical Network
TCP/IP
JXTA Peer: A JXTA node. JXTA Group: a Peer
group is a set of JXTA nodes who share a common interest
Peer Peer
Peer
Peer
Peer
A Rendezvous Peer: a meeting place e.g. gateway for JXTA groups Peer
Peer Peer
Peer Peer
Peer
Peer Peer
Peer
Peer
JXTA Group Peer Peer
Peer Peer
Peer Peer
Peer Peer
• Sekumpulan peer yang memiliki kesamaan layanan/resource, misalnya: file sharing, cpu sharing, dsb •Setiap peer tergabung dalam satu group default yang bernama World Peer Group yang terdiri dari semua JXTA Peers
JXTA • Protokol pada JXTA • Peers : – Discover each others – Self organize into peers group – Advertise and discover network service – Communicate with each others – Monitor each others
JXTA Pipe Output Pipe
Input Pipe
A JXTA Pipe
Peer 1
Peer 2 Actual Route
Peer 3
Firewall
Peer 4
JXTA Scenario 2 1
3
1.
RV
4
2. 3.
New Node
4. . 5. .
5
7 6
JXTA Protocol Layer Peer Discovery Protocol
Via Peer Resolver Protocol
Peer Discovery Protocol
Peer Information Protocol
Via Peer Resolver Protocol
Peer Information Protocol
Pipe Binding Protocol
Via Peer Resolver Protocol
Pipe Binding Protocol
Peer Resolver Protocol
Via Enpoint Routing Protocol
Peer Resolver Protocol
Rendezvous Protocol
Via Enpoint Routing Protocol
Rendezvous Protocol
Peer Endpoint Protocol
Via installed Network Transports
Peer Endpoint Protocol
Network Transport
Via Installed Network Transports
Network Transport
Fungsi-fungsi • Peer discovery protocol: untuk mencari resource yang diinginkan • Peer information protocol: untuk menyimpan informasi mengenai suatu peer (uptime, trafic load, capabilities, state, dsb) • Peer binding protocol: memungkinkan suatu peer membuat sebuah virtual channel (pipe) untuk pertukaran data • Peer resolver protocol: memungkinkan suatu peer mengirimkan suatu kriteria pencarian resource • Redezvous protocol: memungkinkan peer mengirimkan data ke semua peer (listener) pada layanan tertentu • Peer end point protocol: untuk mengirimkan data dari suatu peer ke peer lainnya melalui jalur tertentu
NEXT • Multimedia dan Ubiquitous Computing
