Chunk File Upload

A while back I worked on an AIR client which had to be capable uploading very large files. In this scenario you have to upload files in little chunks. The research on how to solve this took me quite a while so I thought it would make sense to post my findings.

More or less I have taken the NirvanixBinaryUploader as a base and then extended (I should say forked) it to fit my needs.

The class UploadFile takes a file and upload URL as constructor arguments. You can also define a separate resumeUrl if it differs from the upload URL. Further you can set the flag doCalcMD5 to true which is kind of experimental. It works using the as3corelib MD5Stream class but calculating the MD5 hash for large chunks like 1MB took about 20-30 secs on my machine.

I have also implement getters for bytesLoaded and bytesTotal so I can use an instance as a data source for the Flex ProgressBar in polled mode which comes in very handy.

<mx:ProgressBar source="{uploadFile}" mode="polled" label="Uploading" />

If you want to use my code I guess you want to subclass my class because it contains example code and you probably want to override at least the createBody method. However, if you have a similar scenario like me, the code might be a good start.

Another interesting read on this topic was A long journey through chunked transfer and file uploading.

Here now the code: