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| <title>Apache Keep-Alive Support</title> |
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| <h1 align="CENTER">Apache Keep-Alive Support</h1> |
| <hr /> |
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| <h2>What is Keep-Alive?</h2> |
| The Keep-Alive extension to HTTP, as defined by the |
| <code>HTTP/1.1</code> draft, allows persistent connections. |
| These long-lived HTTP sessions allow multiple requests to be |
| send over the same TCP connection, and in some cases have been |
| shown to result in an almost 50% speedup in latency times for |
| HTML documents with lots of images. |
| |
| <h2>Enabling Keep-Alive Support</h2> |
| Apache 1.1 comes with Keep-Alive support on by default, however |
| there are some directives you can use to modify Apache's |
| behavior: |
| |
| <p><strong>Note</strong>: Apache 1.2 uses a different syntax |
| for the <a href="mod/core.html#keepalive">KeepAlive</a> |
| directive.</p> |
| |
| <h3>KeepAlive</h3> |
| <a href="mod/directive-dict.html#Syntax" |
| rel="Help"><strong>Syntax:</strong></a> KeepAlive |
| <em>max-requests</em><br /> |
| <a href="mod/directive-dict.html#Default" |
| rel="Help"><strong>Default:</strong></a> <code>KeepAlive |
| 5</code><br /> |
| <a href="mod/directive-dict.html#Context" |
| rel="Help"><strong>Context:</strong></a> server config<br /> |
| <a href="mod/directive-dict.html#Status" |
| rel="Help"><strong>Status:</strong></a> Core |
| |
| <p>This directive enables Keep-Alive support. Set |
| <em>max-requests</em> to the maximum number of requests you |
| want Apache to entertain per connection. A limit is imposed to |
| prevent a client from hogging your server resources. Set this |
| to <code>0</code> to disable support.</p> |
| |
| <h3>KeepAliveTimeout</h3> |
| <a href="mod/directive-dict.html#Syntax" |
| rel="Help"><strong>Syntax:</strong></a> KeepAliveTimeout |
| <em>seconds</em><br /> |
| <a href="mod/directive-dict.html#Default" |
| rel="Help"><strong>Default:</strong></a> <code>KeepAliveTimeout |
| 15</code><br /> |
| <a href="mod/directive-dict.html#Context" |
| rel="Help"><strong>Context:</strong></a> server config<br /> |
| <a href="mod/directive-dict.html#Status" |
| rel="Help"><strong>Status:</strong></a> Core |
| |
| <p>The number of seconds Apache will wait for a subsequent |
| request before closing the connection. Once a request has been |
| received, the timeout value specified by the <a |
| href="mod/core.html#timeout"><code>Timeout</code></a> directive |
| applies.</p> |
| |
| <h2>When Keep-Alive Is Used</h2> |
| In order for Keep-Alive support to be used, first the browser |
| must support it. Many current browsers, including Netscape |
| Navigator 2.0, and Spyglass Mosaic-based browsers (including |
| Microsoft Internet Explorer) do. Note, however, that some |
| Windows 95-based browsers misbehave with Keep-Alive-supporting |
| servers; they may occasionally hang on a connect. This has been |
| observed with several Windows browsers, and occurs when |
| connecting to any Keep-Alive server, not just Apache. Netscape |
| 3.0b5 and later versions are known to work around this problem. |
| |
| |
| <p>However, Keep-Alive support only is active with files where |
| the length is known beforehand. This means that most CGI |
| scripts, server-side included files and directory listings will |
| not use the Keep-Alive protocol. While this should be |
| completely transparent to the end user, it is something the |
| web-master may want to keep in mind.</p> |
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