Consuming a rest api with Drupal - rest

Question

I am currently maintaining a drupal 7 site. Although I already gained some experience with Drupal my knowledge is still rather low-level and doesn't go beyond installing and configuring modules.
My site is pretty much a metadata repository. People fill in forms about datasets.
My problem is probably rather basic (or maybe not - it's hard to say).
I need to implement an external file repository. The data repository provides a REST API that should allow the users to upload files to their repository using my drupal site.
After uploading a file the data repository then provides a permanent identifier that I have to save in addition to the other fields.
Now I'm looking for the best way to build a very simple UI that allows users to upload their files to the repository without leaving my drupal site (e.g. while they are in the process of filling in the fields). I also need the liberty to form the URLs needed myself as commands for the API as there are many options that need to be declared. For instance I need to provide a certain token in my URLs for the data repository to be able to identify who's uploading.
I already did some research and found modules like:
https://www.drupal.org/project/wsclient
https://www.drupal.org/project/chr
https://www.drupal.org/project/rest_client
or these topics:
http://drupal.stackexchange.com/questions/42103/how-do-i-consume-rest-as-a-client
https://www.drupal.org/node/1114312
However, I still wasn't able to find out what the best strategy is to implement that.
What I need are tips on what the best way is to do that.
Currently I don't really know what I'm looking for.
Also I do realise that the are drupal forums where I could ask a question like this, but I have far more better experiences with stackoverflow.
I'd appreciate any help.
Thanks

Answer 1

Sorry for answering my own question, but based on the information I got from here:
https://drupal.stackexchange.com/questions/42103/how-do-i-consume-rest-as-a-client
I was able to solve the problem.
I wrote a custom drupal module that communicates with the API.
Drupal 7 comes with its own function for https requests:
https://api.drupal.org/api/drupal/includes%21common.inc/function/drupal_http_request/7.x
However, it wasn't enough for my needs as I also neeeded to transfer data, so I ended up using the php library curl (https://curl.haxx.se/), which was built for exactly that purpose.
Basically, you install curl on your server where your drupal installation is also running on. Somewhere in your custom module, preferably in a config menu, you can check if the installation was succesful using something like this:
function _is_curl_installed() {
if (in_array ('curl', get_loaded_extensions())) {
return true;
}
else {
return false;
}
}
if (_is_curl_installed()) {
drupal_set_message(t('Curl is installed.'));
} else {
drupal_set_message(t('Curl is NOT installed.'), 'error');
}
Drupal should be able to recognise curl automatically after the installation.
And here is one example for a rest call in drupal using curl (based on this answer how to upload file using curl with php). Keep in mind that the syntax using '#' is outdated and that drupal will complain about it. In my example I used "new CURLFile".
$request = curl_init($deposit_url);
curl_setopt($request, CURLOPT_POST, true);
$cfile = new CURLFile($file_realpath,'application/octet-stream', $base_file_name);
curl_setopt(
$request,
// the content of the array depends on the API you are communicating with
CURLOPT_POSTFIELDS,
array(
'file' => $cfile,
'access_token' => $temp_token,
'verify' => false,
));
curl_setopt($request, CURLOPT_RETURNTRANSFER, true);
$output= curl_exec($request);
// output the response
// drupal_set_message(t('The curl output [1] is '.$output));
curl_close($request);
I hope this is helpful to someone.
EDIT: I released a contributed module that solves the described problem:
https://www.drupal.org/project/b2share

Answer 2

Yes you can implement nice REST API services using Drupal if you are using drupal 7 try to use "Services" MOdule that would be a great starting point for your project by using this module you can create your own endpoinds and you can intergrate other applications to this endpoinds.