Webbots, Spiders, and Screen Scrapers

Form Handlers, Data Fields, Methods, and Event Triggers

Web-based forms have four main parts, as shown in Figure 5-2:

• A form handler

• One or more data fields

• A method

• One or more event triggers

I'll examine each of these parts in detail and then show how a webbot emulates a form.

Figure 5-2. Parts of a form

Form Handlers

The action attribute in the <form> tag defines the web page that interprets the data entered into the form. We'll refer to this page as the form handler. If there is no defined action, the form handler is the same as the page that contains the form. The examples in Table 5-1 compare the location of form handlers in a variety of conditions. ...