Overviewof

ComputerScience

Much ado about Nothing Computer Science

The field of Computer Science

Not a homogeneous set of Systems

Communications

Applications

Operating Systems

Programming

Hardware

Information

You enter the communications layer

Communication Layer

html, xhtml, xml

ProtocolsHttp, Soap,

web services

Service Description

WSDL, SDL

SecurityEncryption

Internationalization

BrowserInterpretatio

nAnd

rendering

Client

Server

Web services

DatabasesServer

Cloud

Built on top of other layers (hardware, information, application,…)

W3C: Standardization

W3C standards define an Open Web Platform for application development that has the unprecedented potential to enable developers to build rich interactive experiences, powered by vast data stores, that are available on any device. Although the boundaries of the platform continue to evolve, industry leaders speak nearly in unison about how HTML5 will be the cornerstone for this platform. But the full strength of the platform relies on many more technologies that W3C and its partners are creating, including CSS, SVG, WOFF, the Semantic Web stack, XML, and a variety of APIs.

The W3C mission is to lead the World Wide Web to its full potential

by developing protocols and guidelines that ensure the long-term growth of the Web.

Cannot communicate without common standard

www.w3c.org

Hardware Layer

transistorsIC

VLSI

CMOS

Hardware: Moore’s Law

The complexity for minimum component costs has increased at a rate of roughly a factor of two per year.Gordon Moore:"Cramming more components onto integrated circuits", Electronics Magazine 19 April 1965

Information Layer

Hardware

Firmware

Code Data

Information Layer:Coding Data

Wav, au,aiff,vof,mp3

ASCII

Bmp, gif, png, jpeg

Video codecs

Com

pression Strategies

Information Layer

Gates' law is a variant on Wirth's law, borrowing its name from Bill Gates,[7] the founder of Microsoft. It is a humorous and ironic observation that the speed of commercial software generally slows by 50% every 18 months, thereby negating all the benefits of Moore's law. This could occur for a variety of reasons: "featuritis", "code cruft", developer laziness, or a management turnover whose design philosophy does not coincide with the previous manager

software is getting slower more rapidly than hardware becomes

faster

Wirth’s Law

OperatingSystem

Operating System Layer

hardware

software

Data storage hardware interface

communcations

Programing and ApplicationsLayer

Hardware Informtion Layer

Operating Systems

Operating Systems Layer

Operating Systems

Operating SystemsUnix (officially trademarked as UNIX) is a multitasking, multi-user

computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs,

including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, Michael Lesk and Joe Ossanna

linux

Mac OS x Solarius

Programming Layer

This is where you tell the hardware how to solve itQuestion

s

Answers

Input

Output

You have a problem to solve

Analysis of Problem

Translation

Programming LayerUnderstanding the

problemDevising a plan

Carrying out the plan

Examine the solution obtained

1. Analysis and Specification Phase1. Analysis: Understand the problem2. Specification: Specify the problem that the program is to

solve2. Algorithm Development Phase

1. Develop Algorithm: Divide and conquer with known algorithms and

data structures2. Test Algorithm: does it really solve the problem)

3. Implementation Phase1. Code and Test Cycle

4. Maintenance Phase1. Use and Maintain

Key step

Programming Layer

Programming platformsData Structures

AlgorithmsMust fit together to solve problem

Analysis

Which tools can you use?

Programming LayerData Structures (Abstract Data

Types)

Key to Representatio

n:Algorithms act on the

data structures

Stack

Queue

List, Set

Linked list

tree

graph

Search Algorithms

Programming LayerAlgorithms: Basic programming techniques

Divide and Conquer

recursion

loops

Sorting

Applications Layer

Data Structures

Algorithms

CommunicationsProgrammingInformation

hardware

ApplicationFitting together all the

components to perform a complex task

Application Layer

Information Systems

E-commercespreadsheet

s

Relational Databases

Search Engines

Artificial Intelligence

Simulation

Applications in almost every field imaginable

“Simple” Questiongoes through all layers

Simplethought

communicationsApplications

Operating system

programming

informationhardware

The field of Computer Science

Not a homogeneous set of Systems

Communications

Applications

Operating Systems

Programming

Hardware

Information