I see 2 ways to do this (but they inherit the same idea).
The idea is based on the thing you should have something like sessionId
parameter. This value should be unique for each set of files. You could use javascript
uuid
generators or something like so.
Further, this sessionId
variable may be passed through query string(a little bit modified your handler url): ~/UploadHandler.ashx?sessionId={whatever}
or as post parameter(guess, the better way).
The value may be retrieved on the server side by using: context.Request["SessionId"]
for example.
On the client side you should be able to change post parameters or handler url dynamically. It could be done by using:
void addPostParam(name, value)
The addPostParam function adds a
name/value pair that will be sent in
the POST for all files uploaded.
The name/value pair will also appear
in the post_params setting.
or
void setUploadURL(url)
Dynamically modifies the upload_url
setting.
client methods. They should be called from the
fileDialogComplete(number of files selected, number of files queued, total number of files in the queued)
The fileDialogComplete event fires
after the File Selection Dialog window
has been closed and all the selected
files have been processed. The 'number
of files queued' argument indicates
the number of files that were queued
from the dialog selection (as opposed
to the number of files in the queue).
method.
Hope, this helps.