1. Distributed Systems & Networks i206 Fall 2010 John Chuang Some slides adapted from Coulouris, Dollimore and Kindberg

2. John Chuang2 Distributed Systems Bits & Bytes Binary Numbers Number Systems Gates Boolean Logic Circuits CPU Machine Instructions Assembly Instructions Program Algorithms Application Memory Data compression Compiler/ Interpreter Operating System Data Structures Analysis I/O Memory hierarchy Design Methodologies/ Tools Process Truth table Venn Diagram DeMorgan’s Law Numbers, text, audio, video, image, … Decimal, Hexadecimal, Binary AND, OR, NOT, XOR, NAND, NOR, etc. Register, Cache Main Memory, Secondary Storage Context switch Process vs. Thread Locks and deadlocks Op-code, operands Instruction set arch Lossless v. lossy Info entropy & Huffman code Adders, decoders, Memory latches, ALUs, etc. Data Representation Data storage Principles ALUs, Registers, Program Counter, Instruction Register Network Distributed Systems Security Cryptography Standards & Protocols Inter-process Communication Searching, sorting, Encryption, etc. Stacks, queues, maps, trees, graphs, … Big-O UML, CRC TCP/IP, RSA, … Confidentiality Integrity Authentication … C/S, P2P Caching sockets Formal models Finite automata regex

3. John Chuang3 Outline  Distributed systems -Requirements and architectures  Inter-process communications -Socket API and network programming  Networking and Internetworking -Architecture and design -Protocols and standards

4. John Chuang4 What is a Distributed System?  “You know you have one when the crash of a computer you’ve never heard of stops you from getting any work done.” -- Leslie Lamport  “A system in which components located at networked computers communicate and coordinate their actions by passing messages” -- Coulouris, Dollimore and Kindberg, Distributed Systems: Concepts and Design, 3 rd Edition

5. John Chuang5 Example: A typical intranet  Other examples? Source: Coulouris, Dollimore and Kindberg

6. John Chuang6 DS Requirements/Challenges  What are some requirements for distributed systems?

7. John Chuang7 DS Requirements/Challenges  Heterogeneity  Interoperability  Openness  Security  Scalability  Failure Handling  Concurrency  Transparency  Networks  Computer hardware  Operating systems  Programming languages  Implementation by different developers  Owners/operators  Published interfaces  Standardized protocols  Confidentiality, Integrity, Availability, Authentication, Authorization, Accountability

8. John Chuang8 DS Requirements/Challenges  Heterogeneity  Interoperability  Openness  Security  Scalability  Failure Handling  Concurrency  Transparency  Growth in number of users, components, nodes, networks, messages, etc.  Controlling cost of physical/software resources; performance degradation  Any DS component may fail  How to maximize system availability in face of component failures?  Detecting failures  Masking failures  Tolerating failures  Recovery from failures

9. John Chuang9 DS Requirements/Challenges  Heterogeneity  Interoperability  Openness  Security  Scalability  Failure Handling  Concurrency  Transparency  Access transparency  Location transparency  Concurrency transparency  Replication transparency  Failure transparency  Mobility transparency  Performance transparency  Scaling transparency  Concurrency control (transactions)

10. John Chuang10 DS Models  Client-server  Peer-to-peer Source: Coulouris, Dollimore and Kindberg client server

11. John Chuang11 A service provided by multiple servers  Location transparency? Source: Coulouris, Dollimore and Kindberg

12. John Chuang12 Proxy server Source: Coulouris, Dollimore and Kindberg

13. John Chuang13 So, where is the Network? client server Network

14. John Chuang14 Local Exchange Carrier (LEC) Router ISP Backbone Provider 1 Router Client Tandem Switch Inter-exchange Carrier (IXC) Long- Distance Network Corporate LAN Firewall Analog Modem Content Provider Server Router Remote ISP Point of Presence xDSL Modem Cable Modem Packet Network Headend Cable ISP Local Loop DNS Local Ingress Switch Exchange Point Router Internet Service ProvidersCustomer Premises Internet backbonesTelephone Network Local Egress Switch Backbone Provider 2 router Mobile Client Wireless ISP Network: Behind the Cloud