SHARCnet

1
Introduction
2
Readings

• Van Steen and Tanenbaum 5.1
• Coulouris 10.3

3
Definition

• From the Tanenbaum and Steen textbook
• A distributed system is a piece of software that
  ensures that
• A collection of independent computers that
  appears to its users as a single coherent system.

4
Definition

• Quote by Leslie Lamport
• A distributed system is one in which I cannot get
  something done because a machine I've never heard
  of is down.

5
Game Changer 1980s

6
Fundamental Shift

• Gradually went from centralized systems to
  networked systems
• The arrival of PCs and LANs led to applications
  that
• Extracted information from central databases on
  shared file servers
• Extracted information is integrated into
  spreadsheets and other applications on the PC
• Synchronized application updates were required
• Tools needed to monitor and troubleshoot
  performance and other network problems

7
Emerging Characteristics

• Multiple computers
• Concurrent execution
• Independent operation and failures
• Communications
• Ability to communicate
• No tight synchronization
• Relatively easy to expand or scale
• Synchronized application updates

8
Example (Coulouris)
9
Example A Typical Portion of the Internet
(Coulouris)
10
Example Portable and Handheld Devices in a
Distributed System (Coulouris)
11
Evolution

• In the 1990s we saw the explosion of WWW
• Companies began to use the web for information
  sharing and interactions with customers
• Multi-tier applications emerged
• Customers connect (through a browser) to many
  different applications
• Applications hosted on different servers
  residing on different machines

12
RevolutionCloud Computing

• There is an emerging trend to move more and more
  computing functions into large shared data
  centers
• Amazon EC2 hosts data centers for customers
• Google runs all sorts of office applications,
  email, etc on their systems
• Yahoo! wants to be a one-source computing
  solution
• IBM has a vision of computing like electric
  power

13
Cloud Computing Concept
14
Supporting Technologies

• Infrastructure
• Core management and scheduling functions
• Event notification services
• Storage systems (GFS)
• Monitoring, debugging, tuning assistance
• We are increasingly seeing virtualization
  becoming a part of this infrastructure

15
Supporting Technologies

• Not just about hardware
• Software is needed to enable clouds
• Map-Reduce
• BigTable
• Astrolabe
• Amazons shopping cart

16
Course Topics

• We have a limited time
• I would like to focus on the fundamental concepts
  e.g., synchronization, replication, multicast
• Provide some insight into how Amazon, Google work
• Look at the hot topics through a critical
  analysis of papers

17
Undergrad vs Grad

• This is an advanced graduate course
• Projects are not as well defined as found in
  undergraduate courses
• You are expected to learn things outside of the
  lectures
• More emphasis on reading research papers
• More emphasis on presentations

18
Evaluation

• Although I will present in the first part of this
  course I do expect 1 to 2 presentations from each
  student
• You will be required to evaluate papers and
  provide brief reviews
• There is one project

19
Reviews

• Not all papers discussed in class will require a
  review
• The goal of a review is to show that you have
  critically analyzed a paper
• Reviews are one to two pages long

20
Presentations

• Present a paper
• Each paper will have a presenter, advocate and a
  devils advocate
• Present a technology
• Examples Amazon, eBay
• Can involve 2 to 3 people

21
Projects

• Group based
• Creative
• Sufficiently challenging
• Types
• New idea
• Experiment with existing ideas
• Develop an application