Force IE (and other browsers) to use the latest version of your FLEX default.swf file with ColdFusion and cffile.

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Problem

IE refuses to obey http headers for cache-control using cfheader, therefore when new versions of your flex app are published it is not guaranteed IE will load the most current version without manually clearing the browser cache. This will also allow for the default.swf to remain cached until a new version is published.

Solution

Use cffile in an index.cfm (rather than index.html) for the flex app to check for a new default.swf file, if present rename it by appending the current date/time to the file name and store the current date/time string in a version.txt file. Read the value from the version.txt file to append the date time string to the object/embed tags so coldfusion will always point to the latest default.swf file.

Detailed explanation

<!---Set the absoute path of this folder--->
<cfset VARIABLES.currentDirectory =
GetDirectoryFromPath(GetTemplatePath())>

<!--- First, check whether version text file exists. If so
populate swfName variable with contents.--->
<cfif FileExists("#VARIABLES.currentDirectory#version.txt")>
<!---set the string to be appended to the file name for the
default.swf renaming--->
<cffile action="Read"
file="#VARIABLES.currentDirectory#version.txt"
variable="VARIABLES.swfName" >
<cfelse>
<!--- If not let's add one and populate with a string of current
date time. (should only need on first run) --->
<cffile action="Write"
file="#VARIABLES.currentDirectory#version.txt"
output="#dateformat(now(), "yyyy-mm-dd")#-#TimeFormat(now(),
"HHmmss")#">
</cfif>

<!---Check to see if a new default.swf file exists. --->
<cfif FileExists("#VARIABLES.currentDirectory#Default.swf")>
    <!---If so let's see if a previous renamed default.swf file
exists and move it to /old-versions. (Did this to be able to
quickly roll back to previous versions if needed.)---> 
    <cfif
FileExists("#VARIABLES.currentDirectory#default#trim(VARIABLES.swfName)#.swf")>
        <cffile action="move"
source="#VARIABLES.currentDirectory#default#trim(VARIABLES.swfName)#.swf"
destination="#VARIABLES.currentDirectory#\old-versions\"> 
    </cfif>
    <!---Set VARIABLES.swfName to the new date/time
string--->
    <cfset VARIABLES.swfName =
"#dateformat(now(),"yyyy-mm-dd")#-#TimeFormat(now(),"HHmmss")#">
    <!---Rename the default.swf file to include the date/time
string stored in the version.txt file--->
    <cffile action="rename"
source="#VARIABLES.currentDirectory#Default.swf"
destination="#VARIABLES.currentDirectory#Default#trim(VARIABLES.swfName)#.swf"
attributes="normal" nameconflict="overwrite" >
    <!---Write a new text file containing the date/time string
to be appended to the default.swf file on subsequent page views.
Overwrite the existing file--->
    <cffile action="Write"
file="#VARIABLES.currentDirectory#version.txt"
output="#VARIABLES.swfName#" nameconflict="overwrite">
</cfif>

Add <output>#VARIABLES.swfName#</output> after "Default" in your object/embed tags for the default.swf to point to the renamed file.

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