330 Java Tips.pdf - FTP Server

Networking
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Networking
I have difficulty understanding what is the difference between sockets
and ports. They seem to be doing the same thing, receiving/sending
data streams to other computers over network.
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Answer: A port is a software address on a computer on the network--for instance, the
News server is a piece of software that is normally addressed through port 119,
the POP server through port 110, the SMTP server through port 25, and so on. A
socket is a communication path to a port. When you want your program to
communicate over the network, you have give it a way of addressing the port, and
this is done by creating a socket and attaching it to the port.
basically, socket = IP + ports
Sockets provide acces to the port+ip
We were trying to write a mail client using sun's javamail. I was wondering if there is a way
to set the priority of the message.
Commercial mail clients does this by setting the X-priority: field of the smtp header ( 1
means highest and 5 means lowest - I think the rfc allows much more than this ). Looking at
the documentation I could not find any way. I was wondering if any of you have done anything
similar.
Answer: Look at MimeBodyPart::addHeader(String name, String value);
You can add any headers allowed by the RFC spec. :-)
I am trying socket level programming through firewalls. Could somebody tell what Http
tunnelling is and how to achieve that using Java 2?
Answer: As an aside, how do you request your proxy server to fetch a page from the net?
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