What are the limitations of retrieving data from external websites in PHP, and how can they be overcome?

Retrieving data from external websites in PHP can be limited by restrictions set by the external website, such as rate limiting or requiring authentication. To overcome these limitations, you can use techniques like setting user agents, handling cookies, and implementing delays between requests. 

// Example code snippet to retrieve data from an external website with user agent and delay

$url = 'https://www.example.com/data';
$user_agent = 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.3';
$delay = 1; // in seconds

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_USERAGENT, $user_agent);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$result = curl_exec($ch);

// Delay between requests
sleep($delay);

curl_close($ch);

// Process $result as needed

Keywords

cURL cross-origin resource sharing (CORS) HTTP headers SSL certificate validation rate limiting

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