Uploading big files over HTTP

libcurl (C api) could be a viable option

-C/--continue-at Continue/Resume a previous file transfer at the given offset. The given offset is the exact number of bytes that will be skipped, counting from the beginning of the source file before it is transferred to the destination. If used with uploads, the FTP server command SIZE will not be used by curl. Use "-C -" to tell curl to automatically find out where/how to resume the transfer. It then uses the given output/input files to figure that out. If this option is used several times, the last one will be used

I'm eight months late, but I just stumbled upon this question and was surprised that webDAV wasn't mentioned. You could use the HTTP PUT method to upload, and include a Content-Range header to handle resuming and such. A HEAD request would tell you if the file already exists and how big it is. So perhaps something like this:

1) HEAD the remote file

2) If it exists and size == local size, upload is already done

3) If size < local size, add a Content-Range header to request and seek to the appropriate location in local file.

4) Make PUT request to upload the file (or portion of the file, if resuming)

5) If connection fails during PUT request, start over with step 1

You can also list (PROPFIND) and rename (MOVE) files, and create directories (MKCOL) with dav.

I believe both Apache and Lighttpd have dav extensions.

Google have created a Resumable HTTP Upload protocol. See https://developers.google.com/gdata/docs/resumable_upload

You need a standard size (say 256k). If your file "abc.txt", uploaded by user x is 78.3MB it would be 313 full chunks and one smaller chunk.

1. You send a request to upload stating filename and size, as well as number of initial threads.
2. your php code will create a temp folder named after the IP address and filename,
3. Your app can then use MULTIPLE connections to send the data in different threads, so you could be sending chunks 1,111,212,313 at the same time (with separate checksums).
4. your php code saves them to different files and confirms reception after validating the checksum, giving the number of a new chunk to send, or to stop with this thread.
5. After all thread are finished, you would ask the php to join all the files, if something is missing, it would goto 3

You could increase or decrease the number of threads at will, since the app is controlling the sending.

You can easily show a progress indicator, either a simple progress bar, or something close to downthemall's detailed view of chunks.