Transcript Introduction to HTML - Department of Computing and Software

Review of basic concepts
Hardware:
Physical, tangible components.
Software:
Programs and the data used by them.
Program:
A series of instructions that the hardware executes one after
another.
Review of basic concepts
Main Components of a computer system:
C.P.U - consists of a control unit, an arithmetic logic unit
(ALU) and registers.
Main Memory (RAM)
Peripherals – storage devices, I/O devices.
A Controller is the interface between a peripheral and
CPU/BUS.
A Device driver is the software that operates a controller.
Basic Computer Architecture
The Central Processing Unit
Review of basic concepts
• A Bit is the basic unit of storage (1 or 0).
• A Byte – 8 Bits make a Byte. Each byte in memory has an
address.
• A Word is a special unit of storage - depends on type of
CPU- can be 2,4,8 Bytes in size. It represents the amount of
information that is moved through the machine at one time.
Instructions are small steps specified in a binary code for
the computer to carry out some function.
• Binary Code: computer understands a language expressed
as ones and zeros called the machine language. An
Instruction specified in a machine language is called binary
code.
Basic Working of CPU
Storage Boxes
4
5
9
Addition Box
1. Take out the chocolates from box 1 and put them in the
“Addition Box”.
2. Take out the chocolates out from box 2 and put them in the
“Addition Box”.
3. Count the total chocolates in the “Addition Box” and save them
in box 3.
Basic Working of CPU
• Operations 1-3 are instructions Numbers 4,5,9 are Data.
• Instructions operate on Data to get results.
• One of the basic principles of modern computers is that
they store both the instructions and the data in the main
memory and then carry out the instructions one by one.
Basic Working of CPU
If the foregoing addition is to be done by a computer program:
• Put both the instructions as well as the data in the memory.
• Get first instruction from memory, decode and execute it.
• Bring second instruction from memory, decode and execute it.
• Bring third instruction from memory, decode and execute it.
This is called ‘fetch-decode-execute’ cycle.
Fetch - Decode - Execute Cycle
Review of Basic Concepts
Assembly Language
High Level Languages
4GL
Compiler
Interpreter
Review of basic concepts
Network: two or more computers connected together so that
they can exchange data or share resources.
Local area Network (LAN): when all the computers in a
network are located near by (less than 500 m) the network is
called LAN, for example the cluster area in KTH or BSB.
Wide Area Network (WAN): two or more local area
networks connected with each other result in a wide area
network. This also gives rise to the term inter-networking.
Intranet: an Intranet is the name given to the use of Internet
Technologies (e-mail, www) on private corporate networks
whether they are local area networks or wide area networks.
A Computer Network
A Wide Area Network
Internetworking
Review of basic concepts
Internet: is a wide area network connecting many smaller heterogeneous
networks extending to most countries in the world. It has become the
primary vehicle for computer to computer communication and has in access
of ten million computers connected to it directly.
Peer to Peer Networks: are generally small networks in which each
computer on a network can communicate with others directly. Most
computers in the network have about the same capacity. Each node can share
the resources of the other (like the hard disk).
Client/Server Networks: have one or more relatively more powerful
computer in the network that store most of the programs and data files that
other computers in the network may need. These computers are called
“Servers” and the other computers that interact with the “Servers” are called
“Clients”. Part of processing is done at the server and part at the client.
Client/Server programs have two parts – a part operating on the server and a
part operating on the client.
A Peer-to-Peer Network
A Client/Server Network
Review of basic concepts
File Server Networks: in this type of networks the server just
stores and forwards files and all the processing is done at the
computers connected to it.
A Client Program or just a Client is a program that runs on a
user’s computer and requests information from another
computer through a network. The computer on which this
program runs is called a client. So Client can be a machine or
a program.
Protocol: A set of rules and procedures that determine how a
computer system receives and transmits Data.
Review of basic concepts
Information needed for computer to computer communication:
• Address of the computer being contacted.
• Address of the computer making a contact.
• Type of service requested.
• Which portion of the message is an address, and
which portion is the actual request for service.
Listener Process and multiple listeners.
TCP/IP: A widely used protocol for computer to computer
communication.
TCP- Transport Control Protocol
IP – Internet Protocol
Review of basic concepts
IP Address: Uniquely defines a computer connected to the
Internet. e.g. 204.192.116.2 (four numbers separated by a dot)
To facilitate remembering IP addresses, names are given to
computers which are translated into IP addresses by a
computer in the network called Domain Server. These names
are approved by the Internet Naming Authority to ensure that
they are unique. The software that translates the names into IP
addresses is called Domain Name Service (DNS)
World Wide Web (www): is another means of communication
between computers on the Internet. WWW software is based
on Client/Server model.
Web Browser is the program that runs on the user’s computer
and displays HTML formatted pages.
Web Server runs on a computer where the web pages are
stored.
Client / Server Model
Review of basic concepts
HTTP(Hyper Text Transport Protocol):
A set of rules that is used for communication between the
browser and the server. It defines the language the user agent
employs when talking to a server as well as the format of the
responses to be made by the server.
URL: Information on the net is located by using a unique
identifier called the Uniform Resource Locator (URL). It
consists of three parts: Protocol, Machine Address and
Resource Name
e.g. http://www.cas.mcmaster.ca/~cs1ba3/homepage.html
Web Host:The computer in the Internet that stores the Web
pages and runs the Web Server program.
Hosting the web pages:Displaying the Web pages on a Web
Host.
Static Web pages: their content does not change unless
periodically updated.
Dynamic Web pages: are interactive and their content
changes depending upon the request of the user.
Relation Between Browser and Server
Dynamic Web Pages
Dynamic Web Pages
Database Access Technologies
More Internet related concepts
Backbones:
High speed transmission channels that provide fast and direct
paths for data to travel across Internet.
Fiber Optic cable back bones (OC) Optical Carriers 2.48 Gbps.
Digital Subscriber Lines(DSL) T1 (1.544 Mbps), T3 (45 Mbps).
Internet Exchange Points or Network access points (NAP).
Point of Presence (PoP) where an individual connects to Internet.
Post Office Protocol (POP) governs the storage of email messages
on a mail server. POP3 - latest version. It complements SMTP
(Simple Mail Transfer Protocol)
Secure Socket Layer (SSL) Encryption Protocol).
NIC - Network Interface Card.