PHPBuilder - FDF Support in PHP Page 2

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FDF Support in PHP - Page 2

by: Uwe Steinmann
November 16, 2000

How it works

Adobe has developed the portable document format (PDF) and extended it over the last years. One of these extensions are Acrobat Forms which allow a user to input data and send it to the server where it is evaluated, just as HTML forms. Such a PDF document is very similar to a static PDF document, but when you look at it with the Acrobat Reader, you will find areas which can be edited.
There are many input fields available just like in HTML, e.g. a submit and reset button, text input fields, check boxes etc.. Creating such a PDF form requires Acrobat Exchange 3.x or the new Acrobat 4 software, which unfortunately only runs on Windows and MacOS. Both provide a mode to place the different input fields into an existing PDF document. The submit button carries an attribute which specifies the URL to call when it is pressed. This is very similar to HTML, but can differ in the format when the entered data is transfered to the server. Data from HTML forms is transfered using a certain syntax which can be observed in the URL after hitting the submit button. Acrobat Forms support this format, but also FDF (Form Data Format).
FDF is a new format which requires the FDF Toolkit (current version is 4.0) to parse. If PHP has FDF support compiled, it can parse FDF data and access any field by its name. FDF data is currently stored by PHP in the variable HTTP_RAW_POST_DATA (just as HTML data is stored in HTTP_POST_DATA). The actual evaluation of the data has to be done in the PHP script, as opposed to the HTML post data which is evaluated by the PHP engine.
To get an impression of what the FDF data looks like, here is an example:
%FDF-1.2 %âãÏÓ 1 0 obj << /FDF << /Fields [ << /V (This is just some text for testing)/T (comment)>> ....
It is just the first portion of a complete record, but one should be able to clearly identify the input field comment and its value. Here is text for testing.

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