ASP in a Nutshell, 2nd Edition

Form Submission

A user enters input into the fields of a form. When the form is submitted, the data contained in each field of the form is transferred to the server, which then passes it to ASP. This data is sent in the format name=value , where name is the name assigned to the field by the NAME= attribute of the <INPUT> tag, and value is the value entered in that field. For example, if the user enters "Archie" in a field prompting for his first name, the browser may send along the string first_name=Archie.

If the form is written to use METHOD=GET , the form data is appended to the URL as an argument string. If the form contains many fields or if fields contain long strings of text, the complete URL can become very large and unwieldy. In addition, the limit of the number of characters submitted in a GET—typically about 2000—is much lower than in a POST.

If the form instead uses METHOD=POST, the name=value pairs are sent as the body of the request instead of being appended to the URL. In addition to the greater ease of handling of POST requests, most servers offer better performance when extracting data from the body of a request than from a URL in the request header.

Always use the POST method with forms that change something or cause any irreversible action (most do). POST is safer and more efficient; GET should never be used to change anything. In developing your ASP scripts, you can decide whether you want to support data passed to your program using the GET method.