Last week I spent a few hours with Dick Wall of the Java Posse working on an application which combines Google App Engine, Adobe AIR, and Flex. This was a fun experiment that turned into a pretty cool application. The application, named QuickFix, sends an image to Google App Engine which does an “I’m Feeling Lucky” transformation on the image and sends it back. Here’s a screenshot of it fixing one of the photos I took at the Java Posse Roundup this past winter:
You can get the application by going to:
All of the source code can be found in the air-quick-fix project on Google Code.
The division of work between Dick and I worked really well. Dick worked on the back-end code in Python while I worked in Flex on the front-end. We used PyAMF to connect the back-end to the front-end. PyAMF made the whole process very easy. The only challenge was in figuring out how to transform the data types correctly. The first version of the application came together in a couple of hours.
The back-end Python code is really simple. Here is the method that is called from the client (trimmed down a bit):
def fiximage(data): image_in = Image(str(data)) image_in.im_feeling_lucky() image_out = ByteArray() image_out.write(image_in.execute_transforms()) return image_out
In this code, the data which is passed to the method is just a ByteArray containing the image. The data is turned into an Image, the im_feeling_lucky transform is specified, then run – taking the bytes and sending them back to the client.
The front-end Flex code that sends the image to the back-end is also really simple:
The RemoteObject (AMF networking API in Flex) is defined as:
<mx:RemoteObject id="ro" destination="image" endpoint="http://airquickfix.appspot.com/image/">
The function which actually makes the request to the back-end is:
var stream:FileStream = new FileStream(); stream.open(startFile, FileMode.READ); var imageData:ByteArray = new ByteArray(); stream.readBytes(imageData); ro.fiximage(imageData);
In this Flex code the image file is opened, read into a ByteArray, then sent to the fiximage method on the back-end.
There is a bunch of other Flex code that creates the UI, handles selecting, saving, and dragging and dropping images but is all pretty straightforward.
Dick and I really enjoyed creating this application together. It shows off some of the strengths of each technology well and shows how easy it is to use the technologies together. Let us know what you think about the application.