Download external JSON regularly - php

Question

I'm currently using an API which returns a JSON object. I pay per hit, so I would like to minimize my hits. I use this object to fill in images and text on my page. The object that gets returned is very similar to a itunes lookup hit.
A simplified version of my code is this:
<img id="test" src="" alt="Image" />
<script>
$.getJSON( "https://itunes.apple.com/lookup?id=284910350", function( data ) {
document.getElementById('test').setAttribute("src", data.results[0].screenshotUrls[0]);
});
</script>
Everytime a users opens this page, a request gets sent to the server and a hit gets added to my account (obviously). I would like to store the object temporarily on my own server so I can request the data once, and serve a 'local' version to the user. What is the best way to do this? Is it possible to have the file updated every week or so automatically?
Thanks in advance!

Answer 1

It's an easy cron job. Assuming that you can execute bash script in your server:
1 - In your server put a bash script called fetchItune.sh. The content of this script basically stores some curl requests to outside API:
#!/bin/sh
curl -H "Accept: application/json" https://itunes.apple.com/lookup\?id\=284910350 -o /path/to/storage/data.json
You can get fancy with this script e.g. putting the list of endpoints in an array or output to different files, etc. but at the core, just make sure they are valid HTTP requests that accept a JSON response.
2 - Set up a cron job to do it weekly. It could be as simple as putting this script in /etc/cron.weekly if you are using an Ubuntu server. Otherwise, please search through your server documentation. I'm sure there is a section on cron job.
3 - From your JavaScript, request your server endpoint instead of the outside API:
<script>
$.getJSON( "/path/to/storage/data.json", function( data ) {
document.getElementById('test').setAttribute("src", data.results[0].screenshotUrls[0]);
});
</script>
EDIT: You can write PHP script to make request to external API instead of bash script. The principle is the same. I take this directly from PHP curl documentation: http://php.net/manual/en/curl.examples-basic.php
<?php
$ch = curl_init("https://itunes.apple.com/lookup\?id\=284910350");
$fp = fopen("/path/to/storage/data.json", "w");
curl_setopt($ch, CURLOPT_FILE, $fp);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_exec($ch);
curl_close($ch);
fclose($fp);
?>