When you submit the contents of an HTML form to 4D's Web Server, you do so by setting the "action" of the <form> tag:
<form name="form_name" method="post" action="/4dcgi/form_handle">
- or -
<form name="form_name" method="post" action="/4daction/form_handle">
What does 4D do when it receives this form? The first thing that happens is that the COMPILER_WEB method will execute, if it exists. This method should be used to declare variables that may be used to accept data automatically from like-named HTML form items. For instance, if you had this in your HTML form:
<input type="text" name="tWebVar" value="Data from the Web">
And you had the following line in COMPILER_WEB:
Then _after_ COMPILER_WEB executes the tWebVar variable in 4D would have "Data from the Web" as its value.
After COMPILER_WEB Executes, the "On Web Authentication" database method will execute, followed by either "On Web Connection" (for use with /4dcgi/) or the method specified for use with /4daction/.
It is also always a good idea to initialize your form variables in COMPILER_WEB, to make sure you only get the values from the current form submission and not any previous values in case the process is being reused by 4D.