Core Servlets and JavaServer Pages™

7.4. Using Persistent HTTP Connections

One of the problems with HTTP 1.0 was that it required a separate socket connection for each request. When a Web page that includes lots of small images or many applet classes is retrieved, the overhead of establishing all the connections could be significant compared to the actual download time of the documents. Many browsers and servers supported the “keep-alive” extension to address this problem. With this extension, the server tells the browser how many bytes are contained in the response, then leaves the connection open for a certain period of time after returning the document. The client detects that the document has finished loading by monitoring the number of bytes received, and reconnects on the ...