Keep in mind that HTML is a stateless protocol. So you need to find
ways around it. There are 2 ways I use currently,
1st is to use session variables that the server updates as it goes thru
the process and the client does ajax calls at set intervals checking the
session variables (or maybe a database table) for status updates.
2nd method I use is right here:
http://www.bennadel.com/blog/1244-coldfusion-jquery-and-ajax-file-upload-demo.htm
I use that to upload photos and when the system is done processing them
it tells the client to move to the next step.
On 6/8/2014 11:02 PM, Jason Allen wrote:
Hey Guys!
I have a real world design issue I'm starting to get stuck on.
I want users to be able to upload images.
When the image is uploaded, I'm going to run it against some
imagemagick functions to create thumbnails, and some alternate sizes.
Along with the resizing.
As it is right now, I send an ajax/json request to a remote cfc, and
get a response saying that it's been completed successfully or there's
an error. What I'd like to do is have the client updated as various
steps in the process are completed.
I could breakup the client request into several steps, but I need to
make sure this is a complete process in total. If I let the client
initiate each step after getting notice that the current process
completed, the total process could fail much more easily. Once the
server gets the file, it can do everything about without any further
client input. The first few steps are pretty quick AND the client can
pretty much move on once they are done. But the last step might take
awhile.
So I'm thinking I can just make a template for file uploads in general.
1. Client sends request to imageUpload.cfc with file and file details
posted to the request.
2. Server processes file, modifies details (name, extension) if
necessary, saves to disk, creates database entry, and pushes update to
client.
3. Server beings processing of subroutines. Image resizing, virus
checks, etc. As each routine finishes, server pushes update to client.
4. Upon total completely of process, server pushes update to client
saying entire process is completed. This could allow user to move onto
doing different things, and get an alert saying the file
upload/processing has completed.
Best way to do this? I'm seeing some hack ways to use javascript to
keep open http requests and you just flush data out to it. But
apparently it's really just a hack and isn't dependable across all
browsers.
Here's what I'm thinking, and I'm leaning towards B as being the most
reliable way to utilize standard ajax functionality.
a) Send each individual request one at a time to keep the requests
simple post/respose? I don't like this because it requires the client
to initiate each process creating an unnecessary dependancy on the
client to complete the full process.
b) Create a temp file or database record that is updated as the server
finishes processes. The client can query this for updates at a set
frequency. When completed, delete record/file.
Thoughts? If I could keep an open connection with the client, that'd
be awesome, cause I could then just push updates.
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