When using the Flex HttpService object to access an http resource from within your application, take care to test it under Internet Explorer too. Due to a bug in IE you could receive a Http Error or Stream Error in your Flex application when it’s running in https (secure) mode.

Normally when your backend responds to the HTTP request, it’ll use a Cache-control: no-cache, so the browser doesn’t cache the response in its browser cache. (as the response is normally dynamic and could change anytime).

As Flex is running in the Adobe Flash ActiveX player this however instructs IE to already delete the response, before the ActiveX plugin manages to get the results.

You’ll need to change your backend to set the following HTTP Response header:

Cache-Control: no-store

This means: “do not store this response for any longer than necessary to display it” (more info at Atlassian)

Also check out Jim Robson’s blog and Mark Speck’s blog for more research regarding this issue.

The IBM Rational Application Developer 7 (RAD 7) IDE, based on Eclipse 3.3 doesn’t work out-of-the-box with Flex Builder 3. This is due to the IBM Java SDK using a different Xerces version then the one Flex Builder needs.

You’ll likely receive the following error:

java.lang.IllegalAccessError:
org.apache.xerces.util.XMLAttributesImpl$Attribute

Here is an easy guide to get you up and running quickly:

1. Install RAD7
2. Install Flex Builder 3
3. At the end of the install, the installer will complain about not being able to automatically setup an Extension Location. Be sure to execute the given instructions manually
4. Quit RAD7 if running
5. Edit the eclipse.ini file in c:\Program Files\IBM\SDP70 (directory where you installed RAD7)
6. Add the following line on a new line at the end of the file:

-Xbootclasspath/a:c:\progra~1\adobe\flexbu~1\sdks\3.0.0\lib\xercesImpl.jar

Restart RAD7 and open the Flex Development perspective to start developing the next-gen Flex app