The project is a servlet to which people can upload files via, at present, HTTP POST. This is accompanied by Web page(s) providing a front-end to trigger the upload. We have more or less complete control over the servlet, and the Web pages, but don't want to impose any restrictions on the client beyond being a reasonably modern browser with Javascript. No Java applets etc.

Files may potentially be large, and a possible use case is mobile devices on less reliable networks. Some people on the project are demanding the ability to resume an upload if the network connection goes down. I don't think this is possible with plain HTTP and Javascript in a browser, but I'd love to be proved wrong.

Any suggestions?