University of Pretoria

Transcription

1 RESOURCE SHARING IN DISTRIBUTED PEER-TO-PEER INTERNET APPLICATIONS by Theodor Louis Ferdinand Danzfuss submitted in partial fulfillment of the requirements for the degree of Magister Scientia in the Faculty of Engineering, Built Environment and Information Technology University of Pretoria 2003 University of Pretoria

2 University of Pretoria Abstract RESOURCE SHARING IN DISTRIBUTED PEER-TO-PEER INTERNET APPLICATIONS by Theodor Louis Ferdinand Danzfuss Chairperson of the Supervisoty Committee: Professor Judith Bishop Department of Computer Science Master of Science (Computer Science) A dissertation presented on distributed Peer-to-Peer (P2P) Internet applications, focusing on distributed resource sharing as a P2P application. The histoty of Internet applications is researched to point out the roots of P2P applications as well as the dependency between modem technology and legacy technology. P2P applications are compared with traditional client! server applications. A classification system for categorizing P2P applications according to functionality and computing model is devised. The classification system is used to group applications with similar attributes and behavior. Five main mechanisms utilized by all content sharing P2P applications are identified. These mechanisms are node discovety, content discovety, content retrieval, content publishing and content storage. Napster, Gnutella and Freenet are discussed in detail as examples of distributed P2P resource sharing applications which utilize these mechanisms. These applications are then compared to point out similarities and differences. Other P2P initiatives known to the author are briefly presented. Challenges that need to be overcome if P2P applications are to be widely adopted are identified and discussed. A typical content sharing P2P application is

3 implemented for constraint mobile devices such as cell phones. The unique characteristics, possibilities and challenges of P2P on mobile devices are explored. Keywords: Peer-to-peer, P2P, distributed, resource sharing, Internet, Napster, Gnutella, Freenet, mobile, J2ME.

4 TABLE OF CONTENTS 1. Introduction Scope... l 1.2. P2P and the TCP/IP reference model Peer-to-peer purity Resource sharing as an example of peer-to-peer applications Outline A Brief history of internet applications The importance of historical study Evolution of the Internet Early Internet applications Internet grorl Client/Server vs. Peer-to-Peer Introduction Client/server model Peer-to-peer model Potential of the peer-to-peer model Contrasting characteristics Classification Introduction Functional categories Computing model categories Combined classification system Applying the classification system P2P distributed processing vs. Grid computing Mechanisms Introduction Node discovery Content discovery Content retrieval Content publishing Content storage Napster Introduction Node discovery Content discovery Content retrieval Content publishing and storage Discussion The new Napster service Gnutella Introduction Node discovery... 52

5 7.3. Content discovery Content retrieval Content publishing and storage Discussion Freenet Introduction Node discovery Content discovery Content retrieval Content publishing Content storage Discussion A comparison between Napster, Gnutella and Freenet Introduction Content search criteria Connection search criteria Supported file types Routing File download Anonymity Source code Computing model Summary Other peer-to-peer 111ltlatlves Introduction Project}XTA OceanStore SETI@home Entropia Gnougat Challenges Introduction Minimizing the distance between connected nodes Initial node discovery Sustainable participation High bandwidth demand Firewalls Service guarantees Political and social concems Forward compatibility Implenting P2P on constraint mobile devices Introduction Motivation Unique aspects of mobile P2P The P2P phonebook application Routing through phonebook entries II

6 12.6. Platfonn and technology Configuration and profile Limitations of the CLOC / MIDP Iiardware Testing, debugging and emulators Source code P2P Phone book in action Conclusions I-listorical impact Application model Classification Mechanisms Napster, Gnutella and Freenet Research effons Challenges Mobile P2P Future work ill

7 LIST OF FIGURES Page Figure 1: The TCP/IP reference model... 3 Figure 2: Internet growth...19 Figure 3: World Wide Web growth...20 Figure 4: Client/Server model...22 Figure 5: Peer-to-peer model...23 Figure 6: The Napster client performing a search...43 Figure 7: Napster content discovety mechanism...46 Figure 8: Napster search mechanism...47 Figure 9: Napster content retrieval mechanism...48 Figure 10: Bearshare as an example of a Gnutella client...51 Figure 11: Gnutella initial node discovety mechanism...52 Figure 12: Gnutella automatic node discovety mechanism...53 Figure 13: Gnutella content discovety mechanism...54 Figure 14: Gnutella content retrieval mechanism...55 Figure 15: Freenet initial node discovety mechanism...59 Figure 16: Freenet automatic node discovety mechanism...60 Figure 17: Freenet content retrieval mechanism...61 Figure 18: Freenet content publishing mechanismure...63 Figure 19: Launching the P2PPhonebook Figure 20: Rendering phonebook entries Figure 21: Rendering additional commands Figure 22: Rendering entty details Figure 23: Adding new entries Figure 24: Initiating distributed search Figure 25: Rendering search results IV

8 ACRONYMS ADSL API ARPA ASP A1M CSD Q-IK adc CRT DARPA DBMS DHCP DMZ DNS DoD DSL FfP GPRS GUI HIML HITP ICMP IDE IMP IP IRC J2ME JAD JAR JSP JVM ]XME ]XTA KSK KVM LCD MIDP MP3 MPEG MSISDN MSN Asynchronous Digital Subscriber Line Application Programming Interface Advanced Research Projects Agency Active Server Pages Asynchronous Transfer Mode Circuit Switched Data Content Hash Key Connected Limited Device Configuration Cathode Ray Tube Defense Advanced Research Projects Agency Database Management System Dynamic Host Configuration Protocol Demilitarized zone Domain Name System Department of Defense Digital Subscriber Line File Transfer Protocol General Packet Radio Service Graphical User Interface Hyper Text Markup Language Hyper Text Transfer Protocol Internet Control Message Protocol Integrated Development Environment Interface Message Protocol Internet Protocol Internet Relay Chat Java 2 Micro Edition Java Application Descriptor Java Archive Java Server Pages Java Virtual Machine Juxtapose for J2ME Juxtapose Keyword Signed Key Kilo Virtual Machine Liquid Crystal Display Mobile Information Device Profile MPEG 1 Audio Layer 3 Moving Pictures Experts Group Mobile Integrated Services Digital Network (cell phone number) Microsoft Network v

9 NAP NAT NCP NNfP OS OS1 P2P PDA PPP RF RFC RMS ROM SAT SETI SIM SMTP SOAP Sonet SSK TCP Telnet TLC TIL UDP URL VM WMA WWW XML Napster audio file Network Address Translation Network Control Protocol NetwOIk News Transfer Protocol Operating System Open Systems Interconnection Peer to peer Personal Digital Assistant Point-to-point Protocol Radio Frequency Request For Comment Record Management System Read Only Memoty SIM Application Toolkit Search for Extraterrestrial Intelligence Subscriber Identity Module Simple Mail Transfer Protocol Simple Object Access Protocol Synchronous Optical NetwOIk Signed Subspace Key Transmission Control Protocol Telecommunication network Tender Loving Care Time to live User Datagram Protocol Universal Resource Locator Virtual Machine Wmdows Media Audio World Wide Web Extensible Markup Language VI

10 I 'ljxju!d like to express sina:re apprexiatim to Prrfossor Bishop for kr assisfdn(e in tf.e preparatim ofthis dissertatioo. Special thanks to my wife Dulciefor kr 011f}Jing patima:, supjxtrt and TLC Vll