Send More Variables to Flash 6 Player Using New Parameter

By Robert M. Hall of Feasible Impossibilities

I saw that Macromedia is running a contest in their Designer Developer Area where you can submit tips for using Macromedia products and possibly win an iMac! Well I tried to think of something I could submit and came up with this and submitted it a few minutes ago. Hope its useful!

Introduction: A new parameter for both OBJECT and EMBED, FlashVars, is available for the Flash 6 player. It allows a much greater amount of variable information to be passed from your html document than previous methods reliably allowed. In the past an efficient way for getting dynamically changing information into a Flash document was to pass that information in the form of appended URL encoded data after the name of your .swf document (the NAME parameter for OBJECT tag and the SRC parameter for EMBED)

Here is an example where the variable foo will be passed the value bar from the html page loading the .swf file named document.swf :

<OBJECT classid="clsid:D27CDB6E-AE6D-11cf-96B8-444553540000"
codebase="http://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=6,0,29,0" ID=sign_on WIDTH=100% HEIGHT=100%>
<PARAM NAME=movie VALUE="document.swf?foo=bar">
<PARAM NAME=quality VALUE=high>
<PARAM NAME=menu VALUE=false>
<PARAM NAME=bgcolor VALUE=#000000>
<EMBED src="document.swf?foo=bar"
quality=high menu=false bgcolor=#000000 WIDTH=100% HEIGHT=100% TYPE="application/x-shockwave-flash" PLUGINSPAGE="http://www.macromedia.com/shockwave/download/index.cgi?P1_Prod_Version=ShockwaveFlash"></EMBED>
</OBJECT>

This is an easy way to get information that may change into your flash file at load time. Typically a server side function would determine the correct value of foo and at the time the html page with the above tags is requested, the correct value would be dynamically inserted it into the html. From here it is passed into the flash file and available for use. This is essentially a GET request with appended URL encoded information.

With versions of the Flash player prior to 6, this method could fail if the amount of variables exceeded a certain amount of characters in length. This is a limitation of certain browsers and servers in their ability to handle large GET requests.

With the release of the Flash 6 player a new parameter for both the OBJECT and EMBED tags was introduced. Meet: FlashVars. By using the new FlashVars parameter a much greater amount of information can be passed to the Flash document. Here is an example of accomplishing the same objective as above but instead of appending the data to the movie name in URL encoded format, we use the new FlashVars parameter.

  <OBJECT 
classid="clsid:D27CDB6E-AE6D-11cf-96B8-444553540000" 
codebase="http://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=6,0,29,0" 
  ID=sign_on WIDTH=100% HEIGHT=100%>
  <PARAM NAME=movie VALUE="document.swf">
  <PARAM NAME=FlashVars VALUE="foo=bar">
  <PARAM NAME=quality VALUE=high>
  <PARAM NAME=menu VALUE=false>
  <PARAM NAME=bgcolor VALUE=#000000>
  <EMBED src="document.swf" FlashVars="foo=bar" 
quality=high 
  menu=false bgcolor=#000000 WIDTH=100% HEIGHT=100% 
TYPE="application/x-shockwave-flash" 
PLUGINSPAGE="http://www.macromedia.com/shockwave/download/index.cgi?P1_Prod_Version=ShockwaveFlash"></EMBED>
  </OBJECT>

Another benefit for webmasters is that if you are recording the data from GET request in your web server log files, they wont be clogged up with extra data in the url fields. This might be especially attractive to webmasters who filter certain types of GET request from their server for security reasons, or for webmasters who run IDS (Intrusion Detection systems) such as Snort or other fingerprint based IDS's that may have false positives triggered by large GET requests.

Happy Coding! -Rob