1. EEDC
34330
Execution
Environments for Distributed Systems
Distributed
Computing
Master in Computer Architecture,
Networks and Systems - CANS
Homework number: 1
Group number: 51, 52, 53
Group members:
Hui Shang – shanghui89@gmail.com
Malik Adnan – malikadnan78@gmail.com
Zafar Gilani – zafargilani@gmail.com

2. Outline
 What are Distributed Systems (DS)?
 Why do we need Distributed Systems?
 Different types and applications
 Advantages and Disadvantages
 An example of DS - Space Shuttle
 Challenges and Future perspective
 Questions?
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3. What are Distributed Systems?
 Many inter-communicating autonomous entities
scattered over a region.
- Solar system, earth-moon system,ecosystem…
 A collection of independent computers that appear to
the users of the system as a single coherent system
- world wide web, network of stations…
 “ you know you have a distributed system when the
crash of a computer you have never heard of stops
you from getting any work done.” – Leslie Lamport
 The World is distributed!
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4. Why do we need Distributed Systems?
 Collaboration among specialized entities works
more efficiently.
ex: How five senses of your brain work?
Deciding what to eat:
– aroma (how it smells)
– texture (how it looks)
– …
 Availability of powerful yet cheap microprocessors
and continuing advances in communication
technology.
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5. DS in the nature
 Solar system: relevance to inner planets and their
motion.
 Earth-moon system: relevance to how water currents
move over the surface of the earth.
 Ecosystem: Insects and amphibians,Trees and
crops, Vegetables and fruits…
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6. Some examples of DS applications
 The world wide web
 Network of branch office computers- information
system to handle automatic processing of orders.
- Banking systems, ebay …
 Telephone and cellular networks
 Sensor networks.
 Aircraft systems.
 manufacturing systems
- automated assembly line
 .. and more!
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7. Organization of DS
A distributed system organized as middleware. The
middleware layer extends over multiputle machines.
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8. Advantages and Disadvantages
 Advantages
- Economics
cost effective way to increase computing power
- Speed
more computing power than mainframe
- Reliability (fault tolerance)
If one machine crashes, the system as a whole can survive
- Inherent distribution
many applications involve, by their nature, spatially separated machines
- Incremental growth
Computing power grow by adding new machines
- Sharing of resources
banking, reservation systems, printers…
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9. Advantages and Disadvantages
 Disadvantages
- Software
What kind of operating system, programming language and
applications ?
- Network
Problems are created by network infrastructure, loss of messages,
overloading…
- Security
Sharing generate the problem of data security
- More points of failure
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10. Example:DS in space shuttle
Why DS?
 Major components:
– Orbiters,
– Recoverable boosters,
– External tanks,
– Payloads,
– Supporting infrastructure
 These components are
controlled by multiple
custom made
supercomputers during
the launch and re-entry
procedures. Too complex
for the humans to control!!
 DS can balance the
workload.
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11. How DS makes it work?
 Each shuttle had five supercomputers.
 Each was fed by measurements from thousands of
sensors installed all over the shuttle.
 The computers then voted for the most optimal
solution.
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12. Challenges of Distributed System
 Secure communication over public networks
- anyone else see or change the message?
 Build fault-tolerant system
- building reliable system for unreliable components
- nodes fail independently
 Replication, caching ,naming
- placing data and computation for effective resource
sharing
 Coordination and shared state
- how to make agreement?
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13. The future
 Internet is going
to get bigger and
bigger!
 Inter-planetary
internet before
the advent of
humans on other
planets?
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14. DS application in the future
More applications on the following:
 Cloud computing.
 Online distributed file repository:
– Hadoop
 Wireless energy transfer
 And more…
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15. The future ..
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