Is it possible to send POST data across domains using PHP?

Question

I have a main website (with backend SQL database), and I have satellite websites which are all separate domains. Each of these websites are hosted by a provider and have their own SQL databases, however, I don't want to maintain 6 or 7 different databases. Instead I would like just one centralised one.

What I would like, is that when a user submits a form on one of the satellite websites, the data is able to get transmitted and stored in the database of the main website. May have to be via a special URL or something - I really don't know.

Is this possible and if so, how?

I think AJAX may have something to do with it, but I cant seem to get to grips with it and it doesn't seem to work for me. SO I'm hoping this is possible using simple PHP. Any help would be appreciated.

Thanks in advance.

Answer 1

On the server where you are hosting the database, you can setup a PHP web service that would receive post requests from the remote forms and do the communication with the database. You can pass in your post request some extra parameters to differentiate between sources from which the requests are coming.

You will have to be extra careful with such a design idea, as your script would be receiving cross domain requests from different sources and might be prone to CSRF attacks unless you take some extra security measures by validating the sources and forms from which the requests are coming.

In addition to the above mentioned solution, you can also simply allow your sattelite sites to connect to your database directly if such a remote DB connection to your server is supported/enabled.

Answer 2

You can have your satellite sites connect to your central database directly as well. They don't have to be on the same servers. All you need for that to work is a user account on your DB server which allows access from other addresses than localhost.

Answer 3

Yes, it's certainly possible, and probably better to do it server side with PHP rather than client side with AJAX, because on the client you'll run into XSS issues. You'll probably need to build your own API endpoints, and I suggest looking at this article for more info on making the requests.

Answer 4

You can generate post requests and submit to any domain. That's not a problem. Doing cross site requests can be problematic, but would like to see your code!