The initial HTTP request from a browser for an mxml page made to a Macromedia Flex application will generate a series of HTTP Request/Response pairs due to the multiple pieces that comprise a Flex presentation tier interface. Specifically, the HTTP response first returns an HTML wrapper containing the appropriate Embed and Object tags to contain the Flash SWF file. That wrapper also contains references to other HTML and JavaScript files that (partially) provide the History Management feature. As the browser makes additional calls back to Flex for the remaining pieces, the second HTTP Request that occurs is for a small piece of JavaScript code. The third piece of HTTP traffic is a request for the {filename}.mxml.swf file (note the double extension). This request is intercepted by the MXML Servlet which will perform the content cache routine and then return a SWF back to the browser in the response, which is the primary interface to the Flex application. The fourth request is to the flex-internal servlet for a smaller SWF file which contributes to the History Mangement functionality. Together, when a simple mxml application file loads in the browser, there are 4 HTTP Request and Response pairs.

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