Basic User Interactivity with HTML Forms

However, besides displaying HTML-formatted text to users, web browsers also provide a means to solicit data from users and send that data to web servers. They do so by using HTML forms.

The ability to create forms is really the beginning of a true, traditional web application. HTML forms allow web application developers to design standard input forms with widgets such as drop downs, text boxes and buttons. Users can enter in data dynamically using these widgets.

Behind the scenes, once the user enters in their data and hits a submit button, the web browser will collate the user defined values for the form widgets and submit them to the web server using the POST or GET methods of the HTTP protocol. Again, we will discuss the HTTP communication layer aspects in the next section.

What you should do at this point is get comfortable with the idea that HTML provides the syntax for defining forms and that browsers will help you process those forms.

NOTE: Besides dealing with HTML form widgets, web browsers also help you maintain application state. they do so by providing an interface for " cookies".

As you will see later, because HTTP is a stateless protocol, most web applications will need help "remembering" what has happened so far in their workflow.

Consider the example of a web store that might need to keep track of all the items a client has added to a virtual shopping cart. The web store application must keep track of the shopping cart items wherever the user goes on the website, or even whether or not the user leaves the website and returns later!

To help solve this problem of state maintenance, browsers keep a log of all the application activity locally in a "cookie" (an invisible widget of sorts). Applications can access the contents of the cookie so that they can maintain the state.

A Short History of Web Browsers
Introduction to the Web Application Development Environment (Tools)
Extending the Browser with Plug-ins