PPT-Peer-to-Peer Systems and Distributed Hash Tables

COS 518 Advanced Computer Systems Lecture 16 Michael Freedman Credit Slides Adapted from Kyle Jamieson and Daniel Suo PeertoPeer Systems Napster Gnutella BitTorrent challenges Distributed Hash Tables. Case Study: Amazon Dynamo. Steve Ko. Computer Sciences and Engineering. University at Buffalo. Recap. CAP Theorem?. Consistency, Availability, Partition Tolerance. Pick two. Eventual consistency?. Availability and partition tolerance over consistency. Spring 2015. Ki-. Joune. Li . http://isel.cs.pusan.ac.kr/~lik. Pusan National University. An . assignment. Choose an electronic (or electric) device . Define additional functions with. . data storage. . Sections 5.3, 5.4, 5.5, 5.6. 2. Designing a Hash Table. Hash function: establishing a key with an indexed location in a hash table.. E.g. . Index = hash(key) % table_size;. Resolve conflicts: . Need to handle case where multiple keys mapped to the same index.. Distributed Storage. 1. Dennis Kafura – CS5204 – Operating Systems. CS 5204 – Operating Systems. 2. Peer-to-Peer Systems. Definition. : “Peer-to-peer systems can be characterized as distributed systems in which all nodes have identical capabilities and responsibilities, and all communication is symmetric.” –. Plan. I spent the last decade advising on numerous cases where hash tables/functions were used. A few observations on . What data structures I’ve seen implemented and where. What do developers think, were they need help. We have:. Discussed techniques for hashing. Discussed mapping down to a given range . 0, ..., . M. – 1. Now we must deal with collisions. Numerous techniques exist. Containers in general. Specifically linked lists. Hash Tables. . . 0. 1. 2. 3. 4. 451-229-0004. 981-101-0002. 025-612-0001. © 2014 Goodrich, Tamassia, Godlwasser. Presentation for use with the textbook . Data Structures and Algorithms in Java, 6. . Outline. Discuss what a hash method does. translates a string key into an integer . Discuss a few strategies for implementing a hash table. linear probing. quadratic probing. separate chaining hashing. n. . . [from the . techspeak. ] (var. ‘hash clash’) . When used of people, signifies a confusion in associative memory or imagination, especially a persistent one.” . . -. The Hacker's Dictionary . COS . 518. : . Advanced Computer Systems. Lecture . 15. Daniel Suo. [Credit: . All slides copied wholesale from Kyle Jamieson and . Mike Freedman.. Selected . content adapted from B. Karp, R. Morris]. Uri Zwick. Tel Aviv University. Started: . April . 2015. Last update: . January 12, 2017. Hashing with open addressing. “Uniform probing”. Insert key . in the first free position among.  . (Sometimes) assumed to be a . Lecture . 19 . – . BigTable. , Spanner. , . Hashing. Overview. BigTable. Spanner. Hashing Tricks. 2. BigTable. Distributed storage system for managing structured data.. Designed to scale to a very large size. Distributed Hash Tables. Chord, . Kelips. , Dynamo. Galen Marchetti, Cornell University. 1960s – 1999: Research Origins. ARPANET. every node requests and serves content. No self-organization. USENET. Dr. . Barsha. . Mitra. CSIS . Dept. , BITS Pilani, Hyderabad Campus. Introduction. Course ID: SS ZG526, Title: Distributed Computing. allows for flexibly sharing resources (e.g., files and multimedia documents) stored across network-wide computers.