Tracking my script installation - php

Question

I am building a CMS/CRM and want to let users install this software on their server using their databases.
I would like to track some of the data from that installation, like version, so I can send updates to that installation if it is out of date. Like when Wordpress tells you a new version is available.
I also want to be able to track the number of users to be able to charge for the installation.
I am using PHP, MySQL(PDO).
Can you let me know what this process is called and any references to this process would be fantastic.

Answer 1

In your application you may have an array of data you'd like to track; something like this
$data = array(
'domain' => 'http://example.com',
'version' => '1.4.35',
'date_added' => '2014-08-20',
'last_update' => '2014-08-22'
);
Then you could send a request to your server to see if is anything new out there; using cURL or any other method for sending an HTTP request
$curl = curl_init("http://your-server.com/your-service/");
curl_setopt($curl, CURLOPT_HEADER, false);
curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
curl_setopt($curl, CURLOPT_HTTPHEADER, array("Content-type: application/json"));
curl_setopt($curl, CURLOPT_POST, true);
curl_setopt($curl, CURLOPT_POSTFIELDS, json_encode($data)); // convert it to JSON format
$json = curl_exec($curl);
curl_close($curl);
// this is your feedback, in JSON format
$response = json_decode($json, true);
It would be good to check the status, like this, but before the curl_close() call
$status = curl_getinfo($curl, CURLINFO_HTTP_CODE);
if($status == 201){
// ... all fine
}else{
// otherwise, do something but don't use exit() or die() in this case
}
The $response value, after decoding, could look something like this
array(
'some_key' => 'some_value',
'another_key' => 'another_value'
...
);
Now, according to the response, echo a message to the user, like this
if(isset($response['some_key']) && $response['some_key'] == 'some_value')){
echo "An update is out there, Check it out";
}