Setting the KeepAlive property to a value of true indicates
that the client wishes to maintain a persistent connection with the
server. For those clients who wish to retrieve a number of documents,
this is more efficient because the client does not need to connect,
retrieve the document and disconnect each time. Instead, the client
can connect, retrieve each document and then disconnect when it is
finished. If the property value is False, a persistent connection is
not maintained, and the client must establish a connection for each
document that it wishes to retrieve. This property should be set to
the desired value before establishing a connection with the server.
Note that this option is only available for those servers which
support version 1.0 or later of the HTTP protocol. For version 1.0
servers, the connection header field is set to the value
'keep-alive', which instructs compliant servers to maintain a
persistent connection. For version 1.1 and later, persistent
connections are the default. In this case, if the property value is
set to False, the connection header field will be set to the value
'close', telling the server that you wish to close the connection
after the document has been retrieved. It is possible that the server
may choose to close the connection itself, even if it supports
persistent connections. If the server does not support persistent
connections and the KeepAlive property is set to True, the
control will attempt to simulate them by automatically reconnecting
for each request.