Distributed Systems

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Transcript

1. Distributed Systems Distributed Systems, Cloud Computing, Client-Server and Peer-to-Peer models
2. What is a Distributed System? • Collection of interconnected nodes sharing resources on a LAN or WAN network • Implemented using different medium (like cables, optical fiber, satellite) and different protocols (like ATM, Ethernet)
3. Distributed Systems They are made of Hardware and Software but DO NOT share Physical Memory being physically away from each other. This distance influences the communication and makes messaging time much more larger than event computation time. Tm » Te
4. Failures The network can drop messages or partition and lead to message communication failures. If a computer fails in a distributed system another computer can become unusable if it relies heavily on the broken one (e.g.: a filesystem failure)
5. Concurrency Each node can execute many processes at the same time, without waiting other nodes’ replies before proceeding. Parallel computing allows messages to travel asynchronously
6. No global clock • Asynchronous systems have no bounds on time of computing nor time of message delivery • Synchronous systems have known bounds on time of computing and delivery of message
7. Influential trends • Pervasive networking technology allows us to be connected by wired or wireless connections in a large ubiquitous computing network • Increasing demand of multimedia services leads us to see distributed systems as a utility or a commodity
8. Cloud Computing • Storing data and application on remote servers • Accessing them from anywhere through Internet • Nothing to install locally to view contents Inexpensive Efficient Flexible alternative to computers and allows you to work anywhere, at any time. + +
9. Client-Server Model • Nodes on a network have no shared resources directly attached to them • They access file, database, mail, web or print servers from a specific location on the network
10. Features of Client-Server Model • Data is accessed in one centralized location on the network • No data, hardware or software duplication • Once updated on the server, all nodes will see the new version
11. Peer-to-peer model • Each computer shares it’s resources • All nodes can be both clients and servers using or providing services • Normally used in file-sharing networks such as BitTorrent network
12. Thanks!