Internet, is what we talk about

Why Search Engine Optimization?

2009-07-10T12:18:00.004+07:00

E-commerce is a cut throat business. You have to arm yourself with the proper know-how and the tools to make your site a cut above the rest. Each day, more and more sites are clambering to optimize their rankings in websites and if you lose your guard, you may just get trampled on and be left in the abyss filled with so many failed e-commerce sites.

Search Engine Optimization or SEO is a term widely used today by many e-commerce sites. For the past few years and the next ten years or so, search engines would be the most widely used internet tool to find the sites that they need to go to or the product or information they need.

Most people that use search engines use only the ten top search results in the first page. Making it to the first page, more so to the top three is a barometer of a sites success in search engine optimization. You will get a higher ratio of probability in being clicked on when you rank high. The more traffic for your site, the more business you rake in.

But, it is essential to grab a hold of that spot or make your ranking even better. As I aforementioned, each day is a new day for all e-commerce sites to make them selves rank higher using search engine optimization. It is imperative to make your site better and better everyday.

So just what is search engine optimization and do you have to use it? The answer to why you have to use it is an easy one. You need search engine optimization to be number one, or maybe at least make your site income generating.

With search engine optimization you can get the benefit of generating a high traffic volume. Let’s just say you get only a turn out of successful sales with 10 to 20 percent of your traffic. If you get a hundred hits or more a day, you get a good turn out of sales already. If you get only twenty to ten hits a day, you only get one or two if not any at all.

So once again, what is search engine optimization? Search engine optimization is utilizing tools and methods in making your site top ranking in the results of search engines. Getting yourself in the first page and better yet in the top half of the page will ensure that your site will generate public awareness of your site’s existence and subsequently generate more traffic, traffic that could lead to potential income and business.

Search engine optimization requires a lot of work to be fully realized. There are many aspects you have to change in your site or add as well to get search engine optimization. These will include getting lots of information about the keyword phrases that are popular in regards to your sites niche or theme.

You may also need to rewrite your sites contents so that you could get the right keyword phrases in your site without making it too commercial but light and informative. There are certain rules and guidelines to be followed with making your site’s content applicable and conducive to search engine optimization.

You will also need to collaborate with many other sites so that you could get link exchanges and page transfers. The more inbound and outbound traffics generated by sites among others are one of the components search engines uses to rank sites.

Try to search the internet for many useful help. Tips, guidelines and methods for search engine optimization are plenty to be found. Read many articles that can help you optimize your site in search engine results. The more knowledge and information you gather the better. This will all help you in getting those high rankings. This may require a little time and effort in your part but the benefits will be astounding.

If you can part with some money, there are many sites in the internet that can help you in search engine optimization. There are many sites that help in tracking keyword phrases that can help your site. There are also some content writers that have lots of experience in making good keyword laden content for your sites that have good quality.

Act now and see the benefits garner with search engine optimization. All of these will result to better traffic and more business for your site and company.

Network Structure

2007-11-12T13:12:00.000+07:00

In this course, our target is understand the meaning of network infrastructure, differentiate between core and access networks, understanding the meaning of ‘bearer’, and which bearers are used in different parts of the network and ‘node’, and the network configurations to interconnect nodes

Network Infrastructure
• Lines
• Equipment to interconnect the lines

Network Transmission Media
• Copper wire
• Radio transmission lines
• Silicon fibre strands

Types of Copper Wire Lines
• Overhead copper wire
• Twisted pair cable
• Polyquad cable
• Coaxial Cable

Overhead Copper Wire Lines
• Wires suspended from poles and masts
• Wires have to be insulated from one another
• Wires have to be insulated from earth
• Wires have to form a complete end-to-end circuit

Twisted Pair Cable
• Same characteristics as overhead wires
• Less unsightly
• More circuits per route

Polyquad Cable
• Can be used for low frequency radio signals
• Can be used for low rate digital transmission

Coaxial Cable
• Better direct current characteristics than overhead wires or twisted pair cable
• Can be used to transmit high frequency radio signals

Types of Radio Lines
• Microwave - line of sight terrestrial
• Microwave - earth satellite

Microwave Radio - Line of Sight
• Can be affected by adverse weather
• May be subjected to physical obstruction
• Could be harmful to people and/or animals

Fibre Optic Technology
• Uses Light Amplification by Stimulated Emission of Radiation (LASER)
• Precursor was clear atmosphere line of sight
• Then wave guidance
• Technology is still being refined after more than 30 years

Nodes
• Used to:
** Interconnect links or bearers
** Derive communications channels
** Enhance network signals
** Produce, accept, or pass signals

Network Topology
• Fully Interconnected
• Bus
• Ring
• Star
• Interconnected Star
• Interconnected Star Plus Ring
• Through Connected Link
• The Tandem Principle
• Hierarchical Structure

Bearers
• Consist of:
** Copper wire cables
** Fibre-optic cables
** Radio transmission links
• Serve:
** User access networks
** Wide area networks

User Access Networks
• Traditionally a copper wire pair connecting users’ premises to the public network
Often referred to as:
** the local loop
** the last kilometre or mile
** the local distribution network

Transmission Bearer Networks
• Used to link:
** telephone exchanges
** packet switching exchanges
** frame relay exchanges etc
• Analogue networks used coaxial cable and microwave links
• Digital networks use fibre-optic cable
• Used to provide transmission infrastructure

General Overview of Enterprise Networks

2007-11-12T11:52:00.000+07:00

In this tutorial which titled General Overview of Enterprise Networks, we will identify different network types, Ascertain essential network characteristics, Ascertain main network functionality, Understand what is meant by transmission and Appreciate the need for signaling in networks. This is one of about 14 others articles.

Network Functionality
• Separate networks for voice, television, data and text is outmoded
• Separate networks may nevertheless be around for some time
• Ultimately the Public Switched Telephone Network (PSTN) and the Internet will become one
• Mobile networks will remove travel constraints
• Virtual reality will allow physical actions to be conducted remotely

Network Structures
• Start by considering what is needed to be achieved
• Networks must achieve functionality in an economic manner
• A variety of configurations are possible

Network Structures
• Star
• Multi-exchange
• Typical National Network Hierarchy

Typical National Network Hierarchy
• Lines within users’ premises
• Lines to users’ premises (the access network)
• Junction to interconnect local exchanges
• Trunks to interconnect trunk exchanges

Types of Network Node
• User nodes
• Service nodes
• Switching nodes
• Transmission nodes

Network Services
• Historically different networks were provided for different services
• Despite differences a common transmission infrastructure was used

Telecommunications Regulations
• Need to take account of :
** Control of pricing
** Access to customers
** Ensuring effectiveness of competition
** Public network protection from harm

Telecommunications Standards
• Needed to ensure interoperability between different :
** Networks
** Systems
** Countries

Telecommunications Standards Bodies
• International Telecommunications Union (ITU) was CCITT
• ITU consists of ITU-T and ITU-R
• International Standards Organization (ISO)
• European Telecommunications Standards Institute (ETSI)
• America Standards Institute (ANSI)
• Institute of Electrical and Electronic Engineers (IEEE)
• The Association Francais du Normalisation (AFNOR)
• The British Standards Institution (BSI)
• The Deutsches Institute fur Normung (DIN)

Telecommunications Standards Use
• Aid interworking between networks and features
• Aid interconnection between components
• Reduce complexity
• Promote and encourage competition

The ISO Reference Model for Open System Interconnection
• A model to describe all types of networks in 7 discrete layers
• Compliance with one layer ensures interworking with adjacent layers
• Sending layer passes information down to layer beneath until lowest layer is reached
• Information then passes up the layer stack at the receiving end
• Voice network need only comply with layers 1 to 3
• Data networks need to comply with layers 1 to 6

Reference ModelThe ISO Seven Layer
• Physical : Which deals with physical attachment to communications lines.
• Data Link : Which provides transfer and control of data over communications lines, error correction, etc.
• Network : Which adds destination switching, routing and relaying functions and presents these in a manner which is • independent of the actual network in use.
• Transport : Which provides user-to-user services, including multiplexing, to make the most effective use of network facilities. It enhances the quality of the service to that necessary for the application.
• Session : Which controls the dialogue between users and supports synchronization of their activity.
• Presentation : Which allows for the selection of the representation of data, resolving differences between systems.
• Application : Providing the interface to user applications and common services, such as file transfer and terminal support.

Introducing The Internet

2007-11-03T02:45:00.000+07:00

The Internet has created a revolution in the way in which people and businesses communicate. The World Wide Web is the most important application of Internet technologies and no business can ignore the opportunities that it offers. In the late 1990s these opportunities seemed endless and led eventually to the ‘dot com’ boom and to the eventual bust. Despite this speculative bubble, the underlying business benefits of the web are still just as strong, and we are now in a better position to be able to separate unrealistic dreams from good business applications.

The Internet
• Created a revolution in communication
• WWW - most important Internet technology
** No business can ignore the opportunities it offers
** led to ‘dot com’ boom of the 90s, and its eventual bust (business benefits of the web are still as strong)

Internet History
>> The Internet developed from work done in the 60s/70s by the US Department of Defence on the ARPAnet (Advanced Research Projects Agency net) project
** connecting computers in a network
** networks assumed to be unreliable
** resilience was a critical objective

Internet Theory
• A collection of networks
• Any computer can talk to any other
• No single computer in control
• Scalability
Note:
** an internet is an idea - a collection of networks
** the Internet is the implementation of the idea

Communications Networks
• Circuit switched (used by the telephone system)
** complete circuit from sender to receiver
** connections need to be maintained for duration of conversation
** not always the most efficient way of transmitting data between networks
• Packet switched (the Internet uses this approach)
** Message broken into chunks (packets)
** Each packet may take a different route
** Packets can arrive out of sequence
** Users share communication links
** Efficient utilization of communication infrastructure

Internet Protocol (IP) Addresses
• Computers that connect to the Internet are known as hosts
• Each host has a unique address (IP address)
** a.b.c.d (numbers between 0 and 255)
** e.g. Google.com : 64.233.187.99
• Four numbers separated by dots – hence known as the ‘dotted quad’

Internet Protocols
• The Internet is based on well-defined rules - protocols
• Ensure that computers can communicate
• Fundamental to Internet success
• Many communication protocols are created by national and international standards organizations, and documented
• Internet protocols are defined through Request For Comment (RFC) documents

Request For Comment
• Less formal than international standards
• Not all RFCs become standards
• Well defined standardization process
** proposed standard
** draft standard
Internet standard
• Each RFC has a unique serial number (RFC 2026 describes the process)
• Publicly available, free of charge

Internet Protocol
• Rules for transferring packets
• Dependent on IP addresses
• Does not guarantee reliable delivery
**packets could be delivered out of sequence, with unpredictable timing, not delivered at all

Transmission Control Protocol
• Operates on top of IP to produce reliable delivery
** breaks data into packet-sized chunks
** checks for corrupt packets
** checks for missing packets
** requests replacement packets
** re-assembles packets into a message at destination

User Datagram Protocol
• UDP simpler/faster
• All message data in one packet
• No replacement packets
• Useful for simple applications only

Domain Name System (DNS)
• Each host given a textual name in place of numerical IP address
• Words separated by dots
• DNS translates these to the corresponding numerical address

Internet Administration and Funding
• No-one owns the Internet
** a vast number of networks, communications infrastructure and other equipment
• Some funded directly or indirectly by governments
• Other parts of the infrastructure is owned by commercial organizations such as telecommunications companies
** charge for providing a connection to the Internet
• End users (individual home users or businesses) gain access to this network in a variety of different ways
** different types of charges

Types of Charges
• Pay as you go
** user pays the usual telephone charges for making a connection to the ISP - no other fees
** ISP receives a small proportion of the call charge from the telecommunications operator
• Monthly subscription by user to the ISP
** user does not pay for the telephone calls, or alternatively a low fixed rate - more economical for regular Internet end-users
• A fixed fee is paid periodically to an ISP for an ‘always on service’
** typical for small businesses
• Often, ISPs provide additional services such as a technical support, email, special content etc.

The Internet and the Law
• The Internet is not outside the law
• Because of rapid Internet growth, national legislation lags
• Import and export regulations
• Intellectual Property Rights
• Damaging statements
• Network etiquette
• Activities that are unlawful via some other media - usually unlawful if accomplished over the Internet

Internet Applications
• Applications use Internet protocols
• Designed for user interaction
• Quality and usefulness of applications account for the success of the Internet
• Most important applications are:
** electronic mail (email)
** file transfer protocol (ftp)
** remote login (telnet)
** newsgroups (nntp)
** World Wide Web (WWW)
** instant messaging and Internet Relay Chat (IRC)

Electronic Mail
• One of the most heavily used Internet tools
• Uses store-and-forward approach

Email Addresses
• Email relies on the use of addresses
• Address is made up of two parts
** Domain name, e.g. google.com
• The user name, such as joe
** (user_name)@(domain_name)
Example
** joe@google.com
** yazmeen@yahoo.com

Email Message
• Consists of:
** message text
** recipient address
** address of sender
• Other information may be included providing information about:
** who replies should be sent to
** subject for the message
** date and time stamp
• Email clients and servers are used for the processes of preparing, transmitting, receiving and reading emails

Email Client and Server
• Email client, also known as user agent
** edit text message
** recipient address
** carbon copy (cc) / blind carbon copy (bcc)
** sends the message to email server
• Email server
** transmits out-going message
** stores in-coming messages

Multipurpose Internet MailExtension (MIME)
• Conventional email designed to handle 7-bit ASCII text
• Word processed files generally use 8-bit formats
• Many Asian languages cannot be mapped to 7-bit ASCII text
• Encoding scheme used to convert 8-bit files to 7-bit
• Internet standard - MIME
** Email client which complies with this standard used to compose and read messages with 8-bit attachments

FTP
• Protocol designed to facilitate copying files from one host to another
• Used to retrieve files from Internet archives
• Useful for binary and text files
• Login identification
• Anonymous ftp - no user name and password
• Driven by typing simple commands

Telnet
• Protocol which allows remote login to server machine
• Useful for solving problems with web servers
• Simple client program is required to manage connection and display data sent by remote computer
• Terminal emulation, for example:
** DEC VT100
** IBM 3270

Telnet Usage
• Log in to remote machine using a user name and password
• No anonymous login facility (security reasons)
• User name and password sent back to remote machine
** intercepting packets relatively easy, so this is a major security flaw
** extensions to basic telnet protocol can prevent this problem, e.g. SSH

Newsgroups
• Public bulletin board
• Hierarchy of topics
• New newsgroups daily, many fall into disuse quickly
• Main categories:
** comp
** news
** rec
** sci
** soc
** alt
** de, fr, uk
• Similar to email, with additional features
** ‘threads’ allow responses to be followed in sequence to original posting
• Newsreader software required to read and contribute messages
** Outlook Express has some simple newsreading capabilities
• Contributing may lead to ‘spam’

WWW
• Resulted from project started by Tim Berners-Lee at the European Laboratory for Particle Physics (CERN)
• Modern implementation of hypertext idea developed by Ted Nelson in the 60s
• Hypermedia - instead of just text, includes sounds, pictures, etc
• Extended to User navigation from document to document through hyperlinks

WWW Objectives and Operation
• Unify Internet protocols
** telnet
** ftp
** newsgroups
• Browser based navigation
** recognizes references to other documents and provides links
• Content based search engines
• Give user access to any type of material

Browser Features
• Home
** default website
• Forward
** move to next resource in current list
• Back
** move to previous resource
• Search
** call up a search engine to locate a resource

WWW Architecture
• Vast number of web pages connected by links
• Pages (resources) - textual, graphics, sound, video, etc or any combination
• User can follow a link from one resource to another
• Each page is identified by a URL

Browser
• User requests web page by specifying URL
• Browser:
** receives data from web server
** interprets the data
** displays in an appropriate form
** allows user navigation through resource

Uniform Resource Locators
• Used to specify the location and form of a request to a web server
• URL made up of two parts
• Scheme refers to the protocol required
• Most common choices are:
** ftp File Transfer protocol
** http Hypertext Transfer Protocol
** news USENET news
** nntp USENET news using NNTP access

Web Based Email
• Grown in popularity
• Website holds all messages
** access by connecting to website URL and logging into email with name and password
** access from any computer with Internet connectivity
• Advantages for travelers, but…
** access via a fully graphical website is slow
** generally need to be connected for reading and writing (therefore more expensive)
** easier for hackers to access

Instant Messaging
• Email is not spontaneous
** lacks instant feedback of direct communication
• Range of Internet applications that fill this gap, mostly based on old UNIX program ‘talk’
** conversation through keyboard and screen
** extends to ‘conference calls’
• Using the Internet, instant messaging has grown in an unstandardised manner
** many suppliers providing systems that do not work well together
• Several ‘instant message’ services - all popular

Internet Relay Chat (IRC)
• Similar to the newsgroup idea, but all participants can ‘chat’ on line
• Some degree of standardization
• Chat rooms share a common theme
** users can enter or leave at will and possibly create new chat rooms for different topic
• Fast-moving, anarchic, time wasting, BUT…
** closed chat rooms useful for business
** more productive and less expensive than videoconferencing

Voice Over IP
• Process:
** convert analogue voice to digital data
** put data into packets
** transmit using TCP/IP (packets follow different routes (possibly), timing unpredictable)
** assemble packets back into digital data stream
** convert back to analogue signal (with acceptable reproduction of the original audio signal)
• Possible large cost advantages
** e.g. if the mix of calls includes many higher cost destinations

Web Server Part 2

2007-11-02T12:19:00.000+07:00

HTTP Transactions
HTTP is a protocol that allows Web browsers to talk to server and exchange information, it provides a standard way of communicating between browsers and Web servers. HTTP expects the client to initiate a request and the server to respond. Each request and response has three parts:the request or status line, the header fields, and the entity body.

HTTP Request (example)
If we typed http://www.fti.com/index.php, the browser would issue an HTTP request similar the following :
GET /index.php HTTP/1.0
User-Agent : Mozilla/4.5 [en] (X11; SunOs 5.5.1 sun4m)
Accept : image/gif, image/x-xbitmap, image/jpeg

HTTP Response (example)
For the previous example, the server response might look something like this
HTTP/1.1 200 OK
Date : Sat, 15 July 2006 20:00:00 GMT
Server Apache/2.0.54 (Unix)
Last-Modified : Fri, 14 july 2006 21:00:00 GMT
Content-Length : 59
Content-Type : text/html
Welcome to Information Technology Faculty…..

Request Methods
• The request line of a client contains an HTTP command called a request method.
• The server uses the method command to determine what to do with the request.
• The most widely used methods are GET, HEAD, and POST.
• Method commands should be in all-capital letters.
• Other method (PUT, DELETE, etc)

Request Methods
• GET
** Typical way of getting an information (document: static, dynamic, or error message) from a server
** Can be used to pass data to the server, it must be include as part of the URL, followed by a question mark (?) and then parameters.
• HEAD
** Server returns only header data
** Use to verify the existence of a resource
• POST
** Used to send data to the server
** Typically- send HTML form data to the server
** It passes data to the server in the entity body of the request

Server Response
• The server response has three parts :
** Status line -> the protocol version, the status code and description phrase
** Header fields
** Entity body
• The status code is a three digits integer result code defined by the HTTP specification.
• The first digit of the status code represent the category of the spesification.

HTTP Status Code Categories
• (1) : Informational
** The request was received and is being processed.
• (2) : Success
** The client request was successful
• (3) : Redirection
** The client request was not performed; futher action must be taken by the client.
• (4) : Client error
** The client’s request was incomplete or incorrect and cannot be fulfilled.
• (5) : Server error
** The request was not fullfilled, due to a server problem.

HTTP Status Code Categories (Detail)
• Informational 1XX
** 100 Continue
• Successful 2XX
** 200 OK
** 240 No Content
• Redirection 3XX
** 301 Moved permanently
** 302 Found (Moved Temporarily)
** 304 Not Modified
• Client Error 4XX
** 400 Bad Request
** 403 Forbidden
** 404 Not Found
• Server Error 5XX
** 500 Internal Server Error

CLIENT REQUEST HEADER
• Accept
** Used to specify which media types the client prefers to accept.
• Cookie
** Contains cookie information.
• If-Modified-Since
** Used to do a conditional GET request.
• Referer
** Allow the client to specify the URL on the page from which the currently requested URL was obtained
• User-Agent
** Contain information about the client program originating the request.

SERVER RESPONSE HEADERS
• Server
** Contains information about the server software handling the request.
• Set-Cookie
** Allows the server to set a cookie on the client browser permitted) for the given URL or domain.

ENTITY HEADERS
• Content-Length
** Specifies the size (in bytes) of the data transferred the entity body. Only for static documents.
• Content-Type
** Specifies the MIME type of the data returned in the entity body
• Expires
** Specifies the time/date afther which the response is considered outdated.
• Last-Modified
** Specifies the date and time the document was last modified

Proxy Server
• Proxy Servers is an intermediary server that goes between a client and the destination server – a middleman
• Instead of connecting directly to destination server, the browser sends the request to the proxy, the proxy then passes the request to the destination server, receives the response, and passes the response back to the browser.
• Proxy servers have three main uses : security, content filtering and caching.

Main of Uses Proxy Server
• Used for security purposes
** The proxy server can act as a firewall, allowing only HTTP traffict through and rejecting other protocols, limits what kinds of services are available to the people outside your local network.
• Filter data
** The Proxy server restricting access to certain sites or analyzing content for questionable material.
• Caching proxy servers
** The Proxy server stores frequenly accessed web pages, so when one is requested, the cache server can return the page rather than retrieving it from the Internet.
** Make pages that we to to load much quicker.
** Make better use of the ISP’s bandwidth by going outside the local net only when new pages need to be retrieved.

Streaming Audio and Video
• For browser to play audio or video file, it must first download the entire file. It takes a long time.
• The solution : Streaming Media, which allow a media player (or plug-in) to start playing multimedia content while the data is still being received.
• HTTP doesn’t support streaming media, so a different server must be used to publish it.
• Browser don’t support streaming media, so a plug-in must be used to view any type of streaming content.

Streaming Audio and Video
• Many streaming media formats may use UDP (User Datagram Protocol) instead of TCP/IP as a network protocol.
• UDP is a good at transmitting very small pieces of data quickly and digital audio and video. Unlike TCP/IP, UDP will not retransmit data if there is an error, this is fine for digital audio and video because a few bits lost will hardly be noticeable.
• The two leading streaming media packages are RealNetworks’ RealSystem and Microsoft’s Windows Media (formerly NewShow).

Databases
• A database provides an efficient, organized way to store lots of information, BUT most databases don’t provide a friendly interface that anyone can use to access this information. The Web provides a familiar, easy-to-use way of accessing data.
• A large corporate database should typically be installed on its own dedicated server and not on a machine also used as a Web server.
• The database will also have a daemon running to respond the queries; this allows programs on the Web server to communicate with the database server. This type of database daemon is often called a listener.

Secure Sockets Layer
• SSL is a protocol that allow secure, encrypted communication over TCP/IP. It is often used with HTTP to allow information to be exchange securely between a browser and a Web server.
• Most commercial Web server software include an SSL server that can run alongside the HTTPD.
• SSL is used mostly for web transaction, but it can be used to encrypt any communications over TCP/IP.

Web Server Part 1

2007-11-02T06:29:00.000+07:00

How documents are published on the WWW?
How computers on the Internet talk to each other?
How Web pages get from a Web server to a browser?

The underlying technology :
• The communication protocols
• Network terminology
• Document Formats

Clients and Servers
• A Client is a piece of hardware or software used to communicate with a data provider (server)
• A server is usually a large computer capable of providing data to many clients at the same time.
• The word ‘Server’ can mean the physical computer or piece of hardware, or it can refer to the actual server software or daemon running on that machine.
• Server accepts requests from clients, processes the requests and returns the results to the requesting client.
• A Web Server is a spesific type of server that knows how to communicate with clients using HTTP.
• On the Web, the clients are Web browsers (applications especially well suited for displaying HTML content).

History of a Web Server
• The European Laboratory for Particle Physics (CERN) produced one of the first Web Servers.
• The World Wide Web Consortium (W3C) supports a java-based server known as jigsaw.
• CERN HTTPD was dificult to configure and not available for many platforms, so the National Center for Supercomputing Applications (NCSA) wrote their own version.
• Apache is a popular server based on the NCSA implementation.

The First Web Browser
The first real HTML browser, NCSA Mosaic, came into being in early 1993.
• It was free
• It was available for all major platforms : UNIX, Macint0osh, and MS Windows.
• It was easy to create content.

TCP/IP Network Connections/Ports
Standard Port Numbers
• FTP : 20, 21
• Telnet : 23
• SMTP (email) : 25
• HTTP : 80
On unix servers
• Port number below 1023 : root
• Port number above 1024 : normal user

Servers and Browsers
• The main goal of any Web server is to provide documents to clients.
• The purpose of a Web browser is to retrieve and display information from a Web server by using HTTP.
• Browsers have evolved, adding features that far extend the capabilities of browsers that once displayed only basic HTML.

Browsers Plug-Ins
• Extends browser capability
• More than just HTML
• RealPlayer live audio and video
• Shockwave animations
• Acrobat Reader view PDF files

File Types
• ASCII text files
** Letters number and punctuation
** View and edit with standard tools
** HTML
• Binary files
** Images
** Sound
** Programs

HTML Authoring Packages
• Netscape Composer
• Microsoft FrontPage
• Macromedia Dreamweaver
• Adobe PageMill
• Alaire Homesite

Image File Types
• GIF (Graphics Interchange Format)
** 256 colours
** Lossless compression
** Transparency
** Can be animated
** Good for illustrations
** Proprietary (patent)
• PNG (Portable Network Graphic)
** As GIF, except
** more colours
** no animation
** not proprietary
• JPEG (Joint Photographic Experts Group)
** Millions of colours
** Lossy compression
** Good for photographs

Audio File Types
• WAV
** Windows
• AIFF
** Macintosh
• AU
** UNIX
• Modern browsers support all these and More

MIME
• Multipurpose internet mail extensions
• MIME are a set of rules that allow multimedia documents to be exchanged among many different computer systems.
• MIME was originaly designed for sending attachments in e-mail.
• MIME uses media types and subtypes to describe the format of a file.

MIME Types
• Application
** application/excel
• Audio
** audio/midi
• Image
** image/jpeg
• Message
** message/news
• Multipart
** multipart/digest
• Text
** text/html
• Video
** video/mpeg

Request Methods
• GET
** Typical way of getting a resource from a server
** Can be used to pass data to the server
• HEAD
** Server returns only header data
** Use to verify the existence of a resource
• POST
** Used to send data to the server
** Typically- send HTML form data to the server

HTTP Status Code Categories
• Informational
• Success
• Redirection
• Client error
• Server error

FTP
• Copies files from one host to another
• Used to retrieve files from internet archieves
• Useful for binary and text files
• Log in identification

SSL
• Secure Sockets Layer
• Encrypts data in TCP/IP packets
** ordinary HTTP uses clear text
• Commercial web applications
• Web server support