Web Technology
Say, you want to shop online. You open your browser. Your browser is a program (app) running on your computer.
You go to amazon.com and try to look for your books. You are looking for, say, e-business. You submit the search. Now the amazon's computer will search for the item that you are looking for. So your computer and amazon's computer work together. The underlying technology for this to happen is called web technology.
Web Technology may be classified into client side technology and server side technology. In our example, your browser is the client.The browser connects to the store's web server for information. Information such as price of an item or images of a product are typically stored in web documents. A web server processes the request from clients, and finds the requested documents or file, and sends them to the client. If the server cannot find the document requested, it generates an error message. Apache and Internet Information Server (IIS)TM are examples for web servers.
Since some of the actions take place at the client and rest at the server, web programs are generally client side programs or server side programs depending on where they run. Client side programs are run by the client. Examples include HTML, Javascript, and JScript. The server side programs, on the other hand, are executed by the server. A server side program usually accepts input from client, processes the input, and generates output that can be understood by the client. The interaction between client and server usually follows Hypertext Transfer Protocol (HTTP) or Secure HTTP (HTTPS). The difference between HTTP and HTTPS is that, in latter, the communication is secure, thus reducing the chance of a third party reading or modifying the communication. Examples for server side programs are PHP, CGI, Servlets, JSP and ASP.
Figure shows a simplified view of client-server technology. Client requests information from the server and server responds with the information, or an error message if the information cannot be provided. Modern web servers, however, support interactive applications. That is, the client not only can request information, but also can provide information to the server. For example, you can enter shipping address. Your browser sends the information to the server for processing. There are, mainly, two methods for submitting information to server: GET and POST. For simple inputs, a programmer may use GET. For more complex inputs, POST is more suitable.
Web Documents
Web documents are usually written using Hypertext. Hypertext enables a user create links. For example, with normal text, if someone doesn't know the meaning of a word, she needs to lookup a dictionary. With, hypertext, however, the word can be linked to its meaning stored within the document or outside, and all the user needs to do is to click on the link, to know the meaning. This way, one can link from anywhere in the document to anywhere. The computer language in which hypertexts are written is called Hypertext Markup Language (HTML). If you are interested in web technology, first thing you should learn is HTML. W3 School (W3Schools.com) has a tutorial on HTML. All HTML documents have two parts, a Body and a Head. Body is what you see, when the web page is loaded. Head, on the other hand, may contain a title, certain information about the document such as style information among other things. Within the body, the document text appears along with markups. Markups tell how the information is to be displayed. Markup also can also be used to specify links.
Resources: Client Side
- W3 Schools provide useful tutorials on XML, XSL, Schema, HTML, Javascript and so many other areas. (www.W3Schools.com)
Resources: Server Side
- PHP site, as you would imagine, has a number of useful resources on PHP. (www.php.net)
- MySQL is probably one of the most widely used databases for web. MySQL site provides tons of useful information. (www.MySQL.com)
- Java Website. (java.sun.com)
- Read about the popular web server here. (www.apache.org)
- GoogleTM Webmaster Guidelines (www.google.com/support/webmasters)
Other Resources
- World Wide Web Consortium (W3C.org)
