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30 ” HTTP Streams W rapper )); ) ’Referer: http://localhost.example’ )), ’content’ => http_build_query(array( ’param1’ => ’value1’, ’param2’ => ’value2’ )) $response = file_get_contents( ’http://localhost.example/process’, false, $context ); ?> H ere is a walk-through of this example. • ’http’ is the streams wrapper being used. • ’POST’ is the HTTP method of the request. • The ’header’ stream context setting is populated with a string containing HTTP header key -value pairs, in this case for the Content-Type and Referer HTTP headers. The Content-Type header is used to indicate that the request body data is URL-encoded. When multiple custom headers are needed, they must be separated by a carriage return-line feed (“\r\n” also kno wn as CRLF) sequence. The implode function is useful for this if key -value pairs for headers are stored in an enumerated array. • The http_build_query function is being used to construct the body of the request. This function can also be used to construct query strings of URLs for GET requests. • http://localhost.example/process is the URL of the resource being requested. • file_get_contents is called to execute the request, the options for which are passed via the context $context created using stream_context_create. • The body of the response is returned and stored in the variable $response.
HTTP Streams W rapper ” 31 Error H andling Before PHP 5.3.0, an HTTP streams wrapper operation resulting in an HTTP error response (i.e. a 4xx or 5xx status code) causes a PHP -level warning to be emitted. This warning will only contain the HTTP version, the status code, and the status code description. The function calls for such operations generally return false as a result and leave you without a stream resource to check for more information. H ere’s an example of ho w to get what data you can. This situation has been impro ved somewhat in PHP 5.3 with the addition of the ignore_errors context setting. When this setting is set to true, operations resulting in errors are treated the same way as successful operations. H ere’s an example of what that might look like.
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