Send data to website through widget on blog - php

Question

I am looking to create a widget/plugin that can send across a simple variable when clicked. The idea is that when this widget is added to a blog, and clicked by one of its readers, it sends a message across to my domain (for example, www.example.com) with the url of the blog in question (Which can then be used to increment a count or something, for example).
I'm very new to widgets/plugins, so I am not entirely sure if this is possible. I am not looking to be spoonfed with code, just a few pointers in the right direction would be of immense help.
Forgive me, I am yet to try anything as I am unsure of where to start. Please let me know if I need to give any more information, if my tags are incorrect, or if my question is unclear!

Answer 1

Most distributable widget would have following aspects :
Widget Script (Controlled by you) and included by end user in their site.
Something like <script src="http://example.com/yourAwesomeScript.php"></script> where example.com is your site or cdn.
Widget Container (Embedded by the end user) to tell the script where to inject the widget code. If your widget is not position container dependent (for eg. fixed/absolute elements) this can be skipped.
You can use Javascript library such as jQuery to make your life easier to code in Javascript.
I have below very basic widget to subscribe. I am using PHP to output Javascript this will allow your widget to send dynamic data. You can also pass params to your script like
http://example.com/yourAwesomeScript.php?user_key=1234564789
end-user.html
Head
<script src="http://example.com/yourAwesomeScript.php"></script>
Body
<div id="widgetCont"></div>
yourAwesomeScript.php
<?php
if($_POST){
if($_POST['email']){
$new_subscribed = true ; //check and add to database and return if subscribed
if($new_subscribed){
echo "You have successfully subscribed";
}else{
echo "You are already subscribed";
}
}
}else{
?>
$(document).ready(function(){
$input = $('<input/>').prop("type","text").prop("id","widget_email");
$submit = $('<input/>').prop("type","button").prop("value","Subscribe").prop("id","submit_email");
$('#widgetCont').html($input,$submit);
$('#widgetCont #submit_email').click(function(){
$.ajax({
url : "http://example.com/yourAwesomeScript.php",
method : "post",
data : {email:$("#widget_email").val()},
success :function(data){
alert(data);
}
})
});
});
<?php
}
?>
I hope this helps.

Answer 2

In PHP you can use cURL to activate code on another domain. You can set GET or POST variables in cURL that will be sent to that page. These can then be manipulated in PHP via the $_GET and the $_POST arrays.
example of cURL:
http://php.net/manual/en/curl.examples-basic.php

Answer 3

You should try to set up a HTTP service on your domain and then create a widget which perform POST requests against your HTTP service.
A good function for this would be cURL in PHP.
Client URL Library
Here is a small guide of how to use cURL
cURL guide