Do you know of any free Java library which support the HTTP pipelining option of HTTP/1.1 ( http://en.wikipedia.org/wiki/HTTP_pipelining ) ?
I don't think you will find any common ones supporting pipe-lining. Jetty HttpClient seems to support it from document but I couldn't make it to do it.
Please note that Pipeline is different from keep-alive. Keep-alive just means reuse the connection but it may still send only one request at a time over the connection. With pipe-lining, you can send several requests at the same time over the same connection and wait for their respective responses.