{"id":6400,"date":"2016-04-18T10:36:10","date_gmt":"2016-04-18T08:36:10","guid":{"rendered":"http:\/\/help.superhosting.bg\/en\/?p=6400"},"modified":"2022-04-05T21:57:45","modified_gmt":"2022-04-05T18:57:45","slug":"http-headers-request-response-header-fields","status":"publish","type":"ht_kb","link":"https:\/\/help.superhosting.bg\/en\/http-headers-request-response-header-fields.html","title":{"rendered":"HTTP Headers"},"content":{"rendered":"\n

HTTP Header Fields are components of the header section in the\u00a0HTTP request*<\/mark> and HTTP response*<\/mark> messages, transmitted from client to server. The last two might be a web browser and a web server. HTTP header fields contain instructions which determine the HTTP data transfer from server to client. The general HTTP Headers (request, response) are defined in the\u00a0HTTP protocol.<\/p>\n\n\n\n

\"HTTP<\/figure><\/div>\n\n\n\n

Full list of all permanent headers<\/a> as well as free to download provisional headers<\/a>, added by developers, is available at IANA<\/a>: Message Headers<\/a>.<\/p>\n\n\n\n

HTTP header fields consist of field name<\/strong> and field value<\/strong>. They can be generally divided into two types: request fields<\/a> (used by the client) or response fields<\/a> (used by the server). However, some HTTP headers such as Cache-Control<\/a>, Via, Content-Length, Content-Type, etc. might be simultaneously used by client and server.<\/p>\n\n\n\n

<\/span>How to View HTTP Headers?<\/span><\/h2>\n\n\n\n

HTTP request or response headers are viewed via web browser tools such as Web Console for Firefox that can be initiated with the keyboard shortcut Ctrl + Shift + K.<\/p>\n\n\n\n

You can also get HTTP headers by using the following PHP functions: getallheaders()<\/a> apache_request_headers()<\/a> for request or apache_response_headers()<\/a> for response.<\/p>\n\n\n\n

Here are some common client request headers<\/strong>:<\/p>\n\n\n\n

request line<\/td>GET<\/strong> \/http-headers-request-response-header-fields.html HTTP\/1.1<\/strong><\/td><\/tr>
HTTP headers (request)\"info-icon\"\"web<\/td>Accept: text\/html,application\/xhtml+xml,application\/xml;q=0.9,*\/*;q=0.8<\/td><\/tr>
Accept-Encoding: gzip, deflate<\/td><\/tr>
Cache-Control<\/a>: no-cache<\/td><\/tr>
Host<\/a>: help.superhosting.bg<\/td><\/tr>
User-Agent: Mozilla\/5.0 (Windows NT 6.1; WOW64; rv:45.0) Firefox\/45.0<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Here are some common server response headers<\/strong>:<\/p>\n\n\n\n

status line<\/td>HTTP\/1.x 200 OK<\/strong><\/td><\/tr>
HTTP headers (response)\"info-icon\"\"web<\/td>Content-Encoding: gzip<\/td><\/tr>
Content-Type: text\/html; charset=utf-8<\/td><\/tr>
Last-Modified<\/a>: Wed, 30 Mar 2016 08:15:07 GMT<\/td><\/tr>
Server: Apache<\/td><\/tr>
Vary: User-Agent<\/a><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

<\/span>Managing HTTP Headers<\/span><\/h2>\n\n\n\n

HTTP headers are managed and configured in the mod_headers<\/a><\/strong> Apache module through modifying the .htaccess file. For example:<\/p>\n\n\n\n

<IfModule mod_headers.c>\nHeader append Vary: User-Agent\n<\/IfModule><\/code><\/pre>\n\n\n\n
The mod_headers Apache module is enabled and supported on all Linux hosting servers<\/a> by SuperHosting.BG.<\/p>\n\n\n\n
HTTP headers can be also managed through the applications of the hosting account. This can be done via PHP, for example to set up the Last-Modified header that indicates the last modification date of the document:<\/p>\n\n\n\n
$modify_time = filemtime($file);\nheader(\"Last-Modified: \" . gmdate(\"D, d M Y H:i:s\", $modify_time) . \" GMT\");<\/code><\/pre>\n\n\n\n
You can set HTTP server response headers through the header()<\/a> PHP function. The headers_list()<\/a> provides information which HTTP headers have been or will be sent to client. The headers_sent()<\/a> enables you to check if and where the HTTP headers have been sent.<\/p>\n\n\n\n
Be careful while using the header()<\/a> PHP function otherwise you will receive this message: “Warning: Cannot modify header information – headers already sent by\u2026”.<\/p>\n","protected":false},"excerpt":{"rendered":"
HTTP Header Fields are components of the header section in the\u00a0HTTP request and HTTP response messages, transmitted from client to server.<\/p>\n","protected":false},"author":11,"comment_status":"closed","ping_status":"closed","template":"","format":"standard","meta":{"inline_featured_image":false,"_lmt_disableupdate":"","_lmt_disable":"no","footnotes":""},"ht-kb-category":[],"ht-kb-tag":[],"class_list":["post-6400","ht_kb","type-ht_kb","status-publish","format-standard","hentry"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\n\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t