Rails 3 with jumploader

Java applets went out of fashion some years ago, and you don’t see them very often now. But they still can be useful. We had a file upload problem that was not solved by plupload, uploadify, swfupload or any other common solutions.The answer was JumpLoader – with this we can upload files bigger than 2Gb, and it’s got a host of other nice options and features. (Yeh, I know it may not be a good idea to try to send files >2Gb through a browser, but that’s what we need to offer – and at least we can arrange to resume failures.)The downside is that it needs to be code-signed if you do not want your users to see a self signed certificate warning when they run it for the first time. Those certificates are quite expensive ($200 per year depending). But assuming that’s not a problem, let’s dive in and get it working with Rails 3.There are two things you need to send when posting a file upload to rails – the request forgery protection token in with the post params, and the cookie that identifies you in the header.Fortunately, JumpLoader offers us both possibilities.I’ve installed the java files in public/java.  So this is how my applet tag looks, in HAML:And the resulting tag in the HTML output:Here we have set the requestProperties to the session cookie, which ensures it is sent with the request headers.We also tell the applet to ‘fireAppletInitialized’ which is a javascript function.Here is the javascript from the head of the document, in ERB this time:This sets the token in a parameter that will be sent with the posted file. Now the upload should pass the csrf check.Note the 1 second delay before setting the parameter in the applet. This is because I was seeing hangs in Safari when setting the parameter directly from the appletInitialized function.