Concurrent Reading and Writing using Mobile Agents

Distributed Systems and Algorithms

• Sukumar Ghosh
• University of Iowa
• Fall 2012

What is a distributed system?

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What is a distributed system?

• Abstract view: It is a network of processes.
• (The nodes are processes, and the edges are communication channels.)

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• A channel may be physical (wired, wireless) or logical

Example

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• A record of email communication among 436 employees of one of the Hewlett Packard Research Labs during the completion of a project. It is a trivial example of a distributed system.

Facts

• Technology has dramatically reduced the cost of processors, so their population is exploding.
• User demands for services have increased the scale of systems (Facebook has more than500 million users)
• We live in a networked society.

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Examples

• Large networks are very commonplace these days. Think of the world wide web. A few examples of distributed systems are:
• eBay for internet-based auction
• Sensor networks
• BitTorrent (P2P network) for downloading video / audio
• Skype for making free audio and video communication
• Facebook (the oxygen of many people)
• Process control networks in engineering factories
• Computational grids (OSG, Teragrid, SETI@home)
• Network of mobile robots collectively doing a job
• Distance education, net-meeting etc.
• Netbanking
• Vehicular networking

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• What are these?