Thursday, 28 March 2013

Resolution (differences)

This is the effect of using different resolution of pictures on a laptop screen with the resolution of 1366x768 pixels.

1) Picture (348x261 pixel) - laptop screen (1366x768 pixel)

2) Picture (1366x768 pixel) – laptop screen (1366x768 pixel)

Saturday, 2 June 2012

HTML Programming

What is HTML?
  • An acronym for HyperText Markup Language, HTML is the language used to tag various parts of a Web document so browsing software will know how to display that document's links, text, graphics and attached media.
  • a special kind of text document that is used by Web browsers to present text and graphics. The text includes markup tags e.g <p> to indicate the start of a paragraph, and </p> to indicate the end of a paragraph.
  • Hypertext is ordinary text that has been dressed up with extra features, such as formatting, images, multimedia, and links to other resources.
  • Markup is the process of taking ordinary text and adding extra symbols. 
  • Each of the symbols used for markup in HTML is a command that tells a browser how to display the text.
  • HTML (Hypertext Markup Language) is the set of markup symbols or codes inserted in a file intended for display on a World Wide Web browser page. The markup tells the Web browser how to display a Web page's words and images for the user. Each individual markup code is referred to as an element (but many people also refer to as a tag). Some elements come in pairs that indicate when some display effect is to begin and when it is to end.
What is an HTML File?
  • An HTML file is a text file containing small markup tags
  •  The markup tags tell the Web browser how to display the page 
  • An HTML file must have an htm or html file extension (xxx.html, xxx.htm) 
  • An HTML file can be created using a simple text editor

There are three basic levels to the structure of an HTML document.

First is the document structure, which is divided into major sections - such as the head, body and script components
Second are the divisions within each of the major sections such as titles, meta data, divisions, paragraphs, forms and headings.
• The third level exists primarily within each of the major sections. It is the substructure of elements and their children, such as lists and list items, forms and form elements, and tables with table rows and data cells.

1.Basic elements of HTML coding

  • Angle bracket (< >) : signal the browser that a new tag is being used
  • Tag names – some tags indicate formating for a word, sentence, or part of a web page e.g <p>….</p> for new paragraph
  • Attributes - allow to change default value for a particular tag I.e colour, font, font size e. g < font face=“comic sans” > will display text in comic sans not in times the default font for most web browser
  • Presentational : <b>boldface</b>
  • Structure : <h2>Golf</h2>
  • Hypertext : <a href="">Wikipedia</a>,

Telnet and FTP

TCP/IP Applications
• World Wide Web's Hypertext Transfer Protocol (HTTP)
• Simple Mail Transfer Protocol (SMTP)
• File Transfer Protocol (FTP)
• Telnet (Telnet) which lets you logon to remote computers
• Simple Network Management Protocol (SNMP)

Defintion: Telnet is a telecommunications software utility which allows you to become a user on a remote computer. Once you access the remote terminal, you can use it for its intended purposes.
  • Telnet utility does not allow you to transfer and save files to your own computer.
  • Telnet usually works between different operating systems
  • The term "TELNET" also refers to the remote login that's possible on the Internet because of the TELNET Protocol.
  • Telnet allows you to remotely access a computer over the Internet.
    - allows you to create, edit, execute and delete files just as if you were sitting at that computer
  • "Telnet to a host" means to establish a connection across the Internet from one host to another.
  •  Usually, you must have an account on the remote host to be able to login
uses of telnet:

• Connecting to a system to use specific programs such as e-mail and ststistics applications
• Connecting to a networking device for information or configuration purposes – e.g for trouble shooting
• Connecting to an online database of information e.g library catalogue
• Connecting to an online forum to interact and communicate..accessing library’s OPAC the most
popular application during the era of text based internet...

Flies Transfer Protocol : FTP
  •  FTP is a protocol that allow computers to communicate with each other across the Internet to arrange for the transfer of files from one computer to another 
  •  FTP ('File Transfer Protocol') is a way to quickly upload and download files on the Internet
  • Not all computers provide FTP service. Host (server) computers must run FTP server software to manage connections from client machines requiring FTP access to the server¡¦s files
  • FTP provides clients with a window into the server that displays the files that can be copied to the client machine¡¦s storage media.
  • Typically a site on the Internet stores a number of files (they could be application executables, graphics, or audio clips, for example), and runs an FTP server application that waits for transfer requests 
  • Some FTP servers are set up for private use, and access is controlled by a user name and password method.
  • To download a file to your own system, you run an FTP client application (example : WS FTP) that connects to the FTP server, and request a file from a particular directory or folder.
  •  Files can be uploaded to the FTP server, if appropriate access is granted. Many Internet Service Providers limit the size of email attachments (around 5MB). Using FTP, you are only limited by the amount of space you are allocated on the server.
uses of FTP
- Uploading files from PC to Server
- Tranfering files from PC to PC
- Downloading software from server to PC


  •  Quickly transfer large amounts of data between your  clients, vendors, and anyone else who has an Internet connection and FTP client software. 
  • Reduce or eliminate the need to copy data on disks for overnight delivery, saving time and money.
  •  No need for expensive server software and static IP address to host your own site.
  • Share your files with others securely. A user ID and password is needed to access your site.
  • There are two types of FTP:
 "non-anonymous."
  • The most widely used type is anonymous FTP.
  • If a file is stored in an anonymous FTP directory virtually anyone with Internet access and an FTP program of some sort, even a web browser, can download the file.
  • Uploading, on the other hand, is not usually possible with anonymous FTP.
  • Anonymous FTP is used primarily to give the Internet public download access to a particular directory of files. Anyone can download files from the directory, but only the "owner" of directory can upload to the directory.
  •  E.g downloading mp3 player from the host


What is Email?
• A mail, but is sent electronically across the Internet.
• Quickly delivered in seconds or minutes

  • Advantages
– Convenience, Fast speed, Inexpensive, Printable, Reliable, Global, Generality (not limited to text, but graphics, programs, even sounds)
  • Disadvantages
– Misdirection, Interception, Forgery, overload, Funk (Spamming), No response (from the receiver)

What you need is
– The E-mail address of the recipient.
– user@host
• “" is the domain name of the mail server which handles the recipient's mail.
• “Megataman" is the user name of the recipient.
• User name and hostname are separated by

Email server and client
• Email client – software / program that can transfer e-mail from a local host to a local e-mail server.
• Email server – software/program that can send/receive e-mail from/to other email servers.
• Mailbox – An electronic mailbox is a disk file which holds email messages.

Email software (client)
• Graphical Client (User friendly)
• Examples
– Microsoft outlook
– Thunderbird
– Netscape Mail
– etc

Email Software (Server)
• Install the mail server on Linux/Unix or Windows platform.
• Carbon Copy Section (cc)
– Send a message to more than one person, all the recipients will see the list of email addresses.
• Blind Carbon Copy Section (bcc)
– The addresses won’t be seen by the recipients.
– When email is sent to a large group of people who don’t know each other.

Attachment – MIME: Multi-purpose Internet Mail Extension
• A protocol for transmitting non-text information across the Internet. Basically, non-ASCII data is converted to ASCII for transmission and then converted back at the receiver.
• A specification for automatically sending objects other than text in email messages.
• MIME is usually associated with multimedia, such as images, audio recordings, and movies.
• Additional hardware and helper software are usually required.
• Common MIME-compliant mailers:
– pine, metamail, Netscape messenger, MS Outlook

how email works.....