How to record data at the server ?

I am currently developing a small application in PHP + JavaScript, and I would like to know how to record data (XML, but it could be any text) on the server.

The program I have developed allows the user to manipulate information, to add, delete, ..., all locally on his post. I wish he could save his work on my server (which would then reload the file).

The volume of information is too important for me to pass as a parameter to a PHP program.

What solution do I have?

I know only two solutions:

1. Pass data in method get or post. Volumes can be quite significant. For example, you can save a lot of data concatenated in a text area.
2. Upload a file already created on the client (reminder: you can not create a file in javascript or html for security reasons).

With Ajax, this is just the same as the parameter passing of the first point.

You must use the functions fopen () and fputs ().

Thank you for your help.
I will try with the POST.

I read that it could recover the data with PHP. It should go.