Webbots, Spiders, and Screen Scrapers

Writing a Webbot That Sends Email Notifications

Here's a simple webbot that, when run, sends an email notification if a web page has changed since the last time it was checked.^[55] Such a webbot could have many practical uses. For example, it could monitor online auctions or pages on your fantasy football league's website. A modified version of this webbot could even notify you when the balance of your checking account changes. The webbot simply downloads a web page and stores a page signature, a number that uniquely describes the content of the page, in a database. This is also known as a hash, or a series of characters, that represents a test message or a file. In this case, a small hash is used to create a signature that references a file without ...