Bkjia.Com PHP Tutorial PHP has many ways to obtain remote web content, such as using its own functions such as file_get_contents and fopen.
echo file_get_contents("http://www.bkjia.com/abc.php"); ?> |
However, in load balancing such as DNS polling, the same domain name may correspond to multiple servers and multiple IPs. Assume that blog.kcoffee.net is resolved by DNS to three IP addresses: 72.249.146.213, 72.249.146.214, and 72.249.146.215. Every time a user accesses blog.kcoffee.net, the system will access one of the servers based on the corresponding load balancing algorithm.
When I was working on a video project last week, I encountered such a requirement: I needed to access a PHP interface program (assumed to be abc.php) on each server in order to query the transmission status of this server.
At this time, you cannot directly use file_get_contents to access blog.kcoffee.net/abc.php, because it may keep accessing a certain server repeatedly.
Using the method of visiting http://72.249.146.213/abc.php, http://72.249.146.214/abc.php, http://72.249.146.215/abc.php in sequence, in these three servers This is also not possible when the Web Server on the computer is equipped with multiple virtual hosts.
It is not possible to set local hosts, because hosts cannot set multiple IPs corresponding to the same domain name.
Then it can only be achieved through PHP and HTTP protocols: when accessing abc.php, add the blog.kcoffee.net domain name to the header. So, I wrote the following PHP function.
/************************ * Function usage: When the same domain name corresponds to multiple IPs, obtain the remote web page content of the specified server * Creation time: 2008-12-09 * Creator: Zhang Yan (blog.s135.com) * Parameter description: * $ip The IP address of the server * $ host The host name of the server * $url The URL address of the server (excluding domain name) * Return value: * The content of the remote web page obtained * false Access to the remote web page failed ***********************/ function HttpVisit($ ip, $host, $url) $errstr, 90); if (!$fp) { return false; } else { $out = "GET {$url} HTTP/1.1rn"; $out .= "Host:{$host}rn"; $fp, $out); ( $fp ); //Remove the Header information $pos = strpos($response, "rnrn"); + 4); .146.213", "blog.s135.com", "/abc.php"); $server_info2 = HttpVisit("72.249.146.214", "blog.s135.com", "/abc.php") ; $server_info3 = HttpVisit("72.249.146.215", "blog.s135.com", "/abc.php"); ?> |