HTML - HyperText Markup Language
HTML (HyperText Markup Language) is the lingua franca of the Internet. It is the language used to develop web pages. Hypertext means that some text in the HTML document carries a link to a different location, which can be on the same page or another page. On clicking this 'hot spot', the viewer is transferred to that location. Markup means that specific portions of a document are marked up to indicate how they should be displayed in the browser.According to purists, HTML is not a language per se, and they are right in one way. HTML simply consists of tags that are placed around elements, which then changes the properties of these enclosed elements. There are hundreds of HTML tags and some of these are proprietary, which means that only some browsers recognize them.
CGI - Common Gateway Interface
The Common Gateway Interface (CGI) has been around for a long time. It allows the web server software to communicate with other programs running on the server. These external programs are called CGI scripts or CGI programs and are usually written in Perl or 'C'. CGI programs are generally used to process information submitted by visitors via a form on a web page. For example, you might use the search form on a web site to look for 'cars'. When you submit your query, the server receives your request, passes it to the CGI program. The program then looks up the search query term in a database and responds with the appropriate result formatted in HTML code.
Javascript/Jscript
Javascript is a programming language that runs on a web browser. It was developed by the same folks who gave us Netscape and was first implemented in version 2 of the browser. Jscript is Microsofts' implementation of Javascript for Internet Explorer. By the by, Javascript is not a subset of Java, infact, the two languages share little in common (yes, they share a few basic concepts but the syntax is different and so is the application). Naming their language "JavaScript", was just a clever marketing ploy by Netscape Communications. It was initially called Livescript but when Sun Microsystems released Java and it became very popular, Netscape renamed their scripting language to JavaScript.
Javascript runs on the browser (client) and does not require any server software. Thus, it is a client-side scripting language. Since all execution takes place on the browser, Javascript is responsible for most of the interactivity on a web page. Image change or text color change on mouseover, creating mouse trails are all possible through Javascript. The language has also been widely used for basic form validation. This seems logical, as it is better to validate a form on the client side than to make several trips to the server. Javascript is commonly embedded inside the HTML page and is thus visible to the visitor.
Javascript can also be written to run on a server and this is based on the ASP model promoted by Microsoft.
Java
Developed by Sun Microsystems, Java is a very powerful, object-oriented language. A lot many platform dependency issues have been ironed out with the advent of Java. Thus, Java programs for Unix can be made to run on Windows or the Mac system with little or no effort. Much development is taking place on the Java front with new arrivals like Java Beans, Extended Java Beans, and Java applications for various databases and XML. Using Java servlets one can also develop dynamic Java Server Pages (JSP).
Java can also be seen on the Internet in the form of applets embedded in an HTML page. Applets are small Java programs that run on a Java compatible browser.
VBScript
VBScript is a client-based language that runs only on the Internet Explorer and quite naturally, has been developed by Microsoft. Though, the browser market share of Internet Explorer has steadily risen and overtaken that of Netscape, it is still not advisable to use VBScript as a client side language for web pages. I would prefer to use Javascript (or JScript, if you like) as it runs on all popular web browsers - Netscape, Opera, Mozilla and the Internet Explorer. However, VBScript is very often used for developing Active Server Pages (discussed below).
ASP - Active Server Pages
Active Server Pages is a technology promoted by Microsoft. The ASP utilizes some special tags, which can be embedded in the HTML code, to generate dynamic web pages. ASP scripts run on the server, typically, IIS on Windows NT. ASP pages carry the .asp extension that differentiates them from plain HTML pages and instructs the web server to pass the pages through the ASP interpreter. You can use VBScript, Javascript/Jscript or a combination of the two to write ASP pages. The great advantage in using ASP is the ease of maintenance of the web site. However, the downslide is that you become too dependent on Microsoft technologies.
PHP
Open source, great development environment - PHP is a cult. This has been the answer of open source programmers to Microsofts ASP. PHP not only carries all the goodness of ASP but also is more secure and handles databases more easily. It is a known fact that PHP on Apache Web server runs faster than ASP. PHP code is embedded inside the HTML page and can link to databases to generate dynamic HTML content. Furthermore, PHP scripts can be made to run on any operating system with little or no modification.
XML - eXtensible Markup Language
The eXtensible Markup Language is a web page developing language that enables programmers to create customized tags. These customized tags can provide the much-needed functionality not available with HTML. XML documents can be accessed using JSP, PHP etc.
There are several other languages on the Internet such as Perl, Python, VRML (Virtual Reality modeling Language), awk etc., which I have not discussed here. You can search for them on your favorite search engine.
Sunday, February 17, 2008
FTP (File Transfer Protocol)
File Transfer Protocol - FTP
The File Transfer Protocol is an excellent method to transfer (download and send) files from one computer to the other over the Internet. Though you can transfer files using email, it is not a good choice especially when the file size is large or when you need to transfer several files. The objectives of FTP are to:
· promote file (programs or data) sharing
· efficiently transfer data from one computer to another
· encourage indirect or implicit use of remote computers
· provide a common platform for file storages among different hosts
FTP sites
FTP sites are storehouses of hundreds to thousands of files - programs, data, music, video etc. In order to upload or download a file from an FTP site, you need to know the login details - the FTP username and FTP password. Once connected, you can transfer files using the binary or ASCII mode. The binary mode is used for binary files like executable programs, music, images, video etc. while the ASCII mode is employed for plain text files such as those created in Notepad, vi etc.
What is anonymous FTP?
On connection to an FTP site or FTP server, you would typically be asked the login details - a username and password. However, some severs enable what has come to be known as anonymous FTP. On Anonymous FTP servers you can log in with 'anonymous' as username and your email as password. You would then have access to all the data which has been placed in the anonymous FTP section.
FTP and web sites
The File Transfer Protocol is generally used by web developers to upload web sites to the host - the computer that stores the web site. For example, if you buy a web hosting package, the company would provide you with a username and password with which you'll connect to the FTP server to transfer your files.
FTP on your desktopFTP is built into the Unix system and can be accessed by typing ftp at the Unix prompt.FTP is also available in Windows. You need to open an MS-DOS window and type ftp at the Dos prompt. The prompt will change to an FTP prompt. You can open an FTP site with the 'open' command. Type 'quit' to come back to the Dos prompt. To get help, type 'help' or '?' at the FTP prompt. This will list the commands available on your system .
FTP clients
If you plan to FTP on a regular basis, I suggest you use an FTP Client - a dedicated program for FTP. There are many FTP clients available (and some of them are freeware). The interface of each program varies, but the information required is almost the same. You should know your username and password of the site (if it is not anonymous FTP) and the server address.Here is a list of some FTP clients that I have used - FTP clients or FTP programs. I have also put a thorough tutorial on using FTP with a popular and free FTP client - Using FTP with FTP Explorer.
Programming languages on the internetThe capabilities of the Internet have been enhanced and extended by using programming languages with HTML. These languages have been responsible for the dynamic and interactive nature of the Net. New languages and language extensions are being developed to increase the usability of the Internet. Here I will look at some of the important languages that have shape the Internet over the years
The File Transfer Protocol is an excellent method to transfer (download and send) files from one computer to the other over the Internet. Though you can transfer files using email, it is not a good choice especially when the file size is large or when you need to transfer several files. The objectives of FTP are to:
· promote file (programs or data) sharing
· efficiently transfer data from one computer to another
· encourage indirect or implicit use of remote computers
· provide a common platform for file storages among different hosts
FTP sites
FTP sites are storehouses of hundreds to thousands of files - programs, data, music, video etc. In order to upload or download a file from an FTP site, you need to know the login details - the FTP username and FTP password. Once connected, you can transfer files using the binary or ASCII mode. The binary mode is used for binary files like executable programs, music, images, video etc. while the ASCII mode is employed for plain text files such as those created in Notepad, vi etc.
What is anonymous FTP?
On connection to an FTP site or FTP server, you would typically be asked the login details - a username and password. However, some severs enable what has come to be known as anonymous FTP. On Anonymous FTP servers you can log in with 'anonymous' as username and your email as password. You would then have access to all the data which has been placed in the anonymous FTP section.
FTP and web sites
The File Transfer Protocol is generally used by web developers to upload web sites to the host - the computer that stores the web site. For example, if you buy a web hosting package, the company would provide you with a username and password with which you'll connect to the FTP server to transfer your files.
FTP on your desktopFTP is built into the Unix system and can be accessed by typing ftp at the Unix prompt.FTP is also available in Windows. You need to open an MS-DOS window and type ftp at the Dos prompt. The prompt will change to an FTP prompt. You can open an FTP site with the 'open' command. Type 'quit' to come back to the Dos prompt. To get help, type 'help' or '?' at the FTP prompt. This will list the commands available on your system .
FTP clients
If you plan to FTP on a regular basis, I suggest you use an FTP Client - a dedicated program for FTP. There are many FTP clients available (and some of them are freeware). The interface of each program varies, but the information required is almost the same. You should know your username and password of the site (if it is not anonymous FTP) and the server address.Here is a list of some FTP clients that I have used - FTP clients or FTP programs. I have also put a thorough tutorial on using FTP with a popular and free FTP client - Using FTP with FTP Explorer.
Programming languages on the internetThe capabilities of the Internet have been enhanced and extended by using programming languages with HTML. These languages have been responsible for the dynamic and interactive nature of the Net. New languages and language extensions are being developed to increase the usability of the Internet. Here I will look at some of the important languages that have shape the Internet over the years
Sunday, December 9, 2007
Web Technology Basics
WEB BASICS
Internet fundamentals and basics guide
This is a brief article on Internet fundamentals written especially for the beginner. You are encouraged to read the other detailed articles on Internet fundamentals such as email and the world wide web which would provide a stepping stone for learning web development.
The Internet started as a small government project in the United States of America back in 1970s. The Advanced Research Projects Agency (ARPA) linked their computers to ease the transfer of data. This network came to be known as ARPANET and is the birthplace of the Internet.
The Internet is now a huge global network of computers. It is not just one network but consists of thousands of other networks worldwide. No one knows how many computers are connected to the Internet because each day several new machines are added and some old ones taken off. The Internet, you see, is always in a state of flux.
Numerous people and organizations around the globe own the different computers linked to the Internet. Hence, no one is actually in-charge of the Internet. Private companies (government agencies, in some countries) own the Internet backbone through which information flows and various organizations develop the technical aspects of this network.
Email - Internet Fundamentals
The rapid development of the Internet can be attributed to the immense popularity of email. Email has been the most used Internet application because it has revolutionized the way we communicate. Email messages can be received almost instantly and can include images, video and sound in addition to text. Furthermore, interactive emails can be created using HTML.
The World Wide Web - Fundamentals
The World Wide Web, also called WWW or simply the web, is a subset of the Internet. It brings text, images, animation, video, sound and other multimedia content, all under one roof. The Web is changing continuously by absorbing new technologies and updating the old ones. The pages on the Web, appropriately called web pages, can contain multimedia objects such as images, sound, and video in addition to text. Highly interactive web pages can be developed using HTML and a client-side language such as JavaScript or VBScript. This greatly enhances the web experience for the web surfer. Web pages are viewed using browsers such as Internet Explorer (from Microsoft), Firefox (from Mozilla), Opera (from Opera Software) and Netscape Communicator (from Netscape). A list of web browsers can be found in the Web page Design section of this web site.With video conferencing and wireless applications, the Internet is ready to take us to the new realm of communication and information exchange.
The World Wide Web (WWW) basics and fundamentals
The World Wide Web (also known as the Web, WWW or W3) is a system of Internet servers through which several Internet protocols can be accessed using a single interface (your browser). Almost all protocols available on the Internet are available on the Web. This creates a convenient and user-friendly environment through which email, FTP, Telnet, Usenet News etc. can be accessed. Because of this and also because of the ability of the Web to work with multimedia and advanced programming languages, the World Wide Web has been the fastest growing and the most interesting part of the Internet.Note: The World Wide Web is a subset of the Internet.
The World Wide Web's HTTP Protocol
One of the most famous and popular protocols on the web is the Hypertext Transfer Protocol (HTTP). Hypertext documents contain links that connect to other documents or files. The user can activate these links or 'hot spots' (through a mouse button click, for example) and the target document will then be transferred on to the client machine and if it's a web page, it would be displayed in the browser. These 'hot spots' are created using the HyperText Markup Language (HTML) and can be placed as text, pictures etc. A single HyperText document can contain many such hyperlinks. Because of all this "linking", a virtual web of connections can be made.
Web Pages are created with HTML
HTML files or web pages are plain text (ASCII) files with a lot of tags. These tags are the building blocks of HTML. The tags help in structuring a document and displaying visual features such as font size, color, italics etc. The tags are also used in creating hyperlinks and embedding images, sounds, video and other multimedia content. HTML tags come in pairs (most of the times); there is a starting and a closing tag. Tag names and tag attributes are enclosed in <> signs.
Let us look at a simple tag - The Bold tag that displays text in bold.The starting bold tag is and the ending tag is . Any text enclosed between these is rendered (displayed) in bold by the browser. Remember all closing tags have the extra slash (/).
Web Browsers
Though the World Wide Web is a part of the Internet, it serves as an important interface through which all of the net can be accessed. This interface to the Internet is the browser. The browser displays the HTML files using the instructions in the tags. In addition, the browser can also display images and video.
The web has grown tremendously over the few years and provides a vast range of experiences including video, multimedia presentations, real-time collaboration, interactive pages, radio and television broadcasts. With the use of programming languages such as JavaScript, VBScript, Perl, PHP, ASP, Java, VRML, the functionality of the web is being increased. The pages on the web can also be linked to databases to provide dynamic content to the visitor. This feature attests the active and energetic nature of the web.
Internet fundamentals and basics guide
This is a brief article on Internet fundamentals written especially for the beginner. You are encouraged to read the other detailed articles on Internet fundamentals such as email and the world wide web which would provide a stepping stone for learning web development.
The Internet started as a small government project in the United States of America back in 1970s. The Advanced Research Projects Agency (ARPA) linked their computers to ease the transfer of data. This network came to be known as ARPANET and is the birthplace of the Internet.
The Internet is now a huge global network of computers. It is not just one network but consists of thousands of other networks worldwide. No one knows how many computers are connected to the Internet because each day several new machines are added and some old ones taken off. The Internet, you see, is always in a state of flux.
Numerous people and organizations around the globe own the different computers linked to the Internet. Hence, no one is actually in-charge of the Internet. Private companies (government agencies, in some countries) own the Internet backbone through which information flows and various organizations develop the technical aspects of this network.
Email - Internet Fundamentals
The rapid development of the Internet can be attributed to the immense popularity of email. Email has been the most used Internet application because it has revolutionized the way we communicate. Email messages can be received almost instantly and can include images, video and sound in addition to text. Furthermore, interactive emails can be created using HTML.
The World Wide Web - Fundamentals
The World Wide Web, also called WWW or simply the web, is a subset of the Internet. It brings text, images, animation, video, sound and other multimedia content, all under one roof. The Web is changing continuously by absorbing new technologies and updating the old ones. The pages on the Web, appropriately called web pages, can contain multimedia objects such as images, sound, and video in addition to text. Highly interactive web pages can be developed using HTML and a client-side language such as JavaScript or VBScript. This greatly enhances the web experience for the web surfer. Web pages are viewed using browsers such as Internet Explorer (from Microsoft), Firefox (from Mozilla), Opera (from Opera Software) and Netscape Communicator (from Netscape). A list of web browsers can be found in the Web page Design section of this web site.With video conferencing and wireless applications, the Internet is ready to take us to the new realm of communication and information exchange.
The World Wide Web (WWW) basics and fundamentals
The World Wide Web (also known as the Web, WWW or W3) is a system of Internet servers through which several Internet protocols can be accessed using a single interface (your browser). Almost all protocols available on the Internet are available on the Web. This creates a convenient and user-friendly environment through which email, FTP, Telnet, Usenet News etc. can be accessed. Because of this and also because of the ability of the Web to work with multimedia and advanced programming languages, the World Wide Web has been the fastest growing and the most interesting part of the Internet.Note: The World Wide Web is a subset of the Internet.
The World Wide Web's HTTP Protocol
One of the most famous and popular protocols on the web is the Hypertext Transfer Protocol (HTTP). Hypertext documents contain links that connect to other documents or files. The user can activate these links or 'hot spots' (through a mouse button click, for example) and the target document will then be transferred on to the client machine and if it's a web page, it would be displayed in the browser. These 'hot spots' are created using the HyperText Markup Language (HTML) and can be placed as text, pictures etc. A single HyperText document can contain many such hyperlinks. Because of all this "linking", a virtual web of connections can be made.
Web Pages are created with HTML
HTML files or web pages are plain text (ASCII) files with a lot of tags. These tags are the building blocks of HTML. The tags help in structuring a document and displaying visual features such as font size, color, italics etc. The tags are also used in creating hyperlinks and embedding images, sounds, video and other multimedia content. HTML tags come in pairs (most of the times); there is a starting and a closing tag. Tag names and tag attributes are enclosed in <> signs.
Let us look at a simple tag - The Bold tag that displays text in bold.The starting bold tag is and the ending tag is . Any text enclosed between these is rendered (displayed) in bold by the browser. Remember all closing tags have the extra slash (/).
Web Browsers
Though the World Wide Web is a part of the Internet, it serves as an important interface through which all of the net can be accessed. This interface to the Internet is the browser. The browser displays the HTML files using the instructions in the tags. In addition, the browser can also display images and video.
The web has grown tremendously over the few years and provides a vast range of experiences including video, multimedia presentations, real-time collaboration, interactive pages, radio and television broadcasts. With the use of programming languages such as JavaScript, VBScript, Perl, PHP, ASP, Java, VRML, the functionality of the web is being increased. The pages on the web can also be linked to databases to provide dynamic content to the visitor. This feature attests the active and energetic nature of the web.
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