Re: [VANILLA-LIST:3019] technical question

[Dave Ahn <ahn@vec.wfubmc.edu>]

On Wed, Mar 22, 2000 at 04:26:35PM -0500, Chawla, Jay wrote:
> 
> What I really need to do right now is send to the court a list of all the
> 'prior art' I will be using against the claim.  Is there anything you
> haven't told me about that could prove that Netrek is doing what's in the
> claim prior to 1995?  You gave me the location of the source code (
> ftp://ftp.netrek.org/pub/netrek/ ).  Is there any other source code, design
> documents, or instructions that I don't know about?

Quite a bit, but most of them are accessible from www.netrek.org or
ftp.netrek.org.  They serve as portal and meta archive to the Netrek
community and contain copies of or references to almost all known Netrek
resource (documents, source code, etc) on the Internet.  If the court
is satisfied with the URLs to these sites, then you should be able to
use all the content from these sites to support your case.  However,
you may wish to just list off the major Netrek sites and all the files
from ftp.netrek.org to be explicit about it.

Key Netrek sites include (but aren't limited to):

	http://www.netrek.org/
	ftp://ftp.netrek.org/pub/netrek/
	http://vanilla.netrek.org/
	http://sourceforge.net/project/?group_id=968
	http://shell3.ba.best.com/~doosh/netrek/netrekFAQ.html
	Usenet:rec.games.netrek
	http://www.ecst.csuchico.edu/~netrek/history/
	ftp://ftp.risc.uni-linz.ac.at/pub/netrek/
	http://www.deja.com/ (Usenet rec.games.netrek archive)

Including post-1995 documents and source code should help because you
can work backwards from post-1995 files to prove that aggregate messaging
in Netrek was clearly _not_ added after 1995.

You may also want to reference this mailing list and the team of Netrek
developers.


As for an explanation IP...well, there is a reason why some IP books are
a thousand pages thick.

> TCP is a connection oriented protocol -- mail servers use it to send mail
> and IRC servers use it to send messages.

I don't know if IRC uses TCP.  TCP is used by most network applications
because guaranteed delivery is critical.  If you send an email message,
you want to be sure that the data packets representing that email message
arrive at the destination mail server.  To ensure this, TCP has built-in
error checking, delivery confirmation and other features.  But these
features add latency in a less than ideal network connection.

> TCP sockets are point to point and one-way between two transport-level
> entities.  You write things to a socket whenever you want, and what
> you're writing goes into a buffer.

You're getting into the implementation of IP at the operation system level.

> So if I send
> 3 IP packets to the socket in a short enough time, they'll all be buffered.
> Periodically, the buffer is emptied.  So the three IP packets will be
> 'aggregated' into one 'packet'.  But this makes no sense to me!  Are these 3
> IP packets encapsulated in a single IP packet and sent through the socket?
> Do routers along the path from source to destination see them as a single
> packet?

Data written to the socket is raw data.  The operating system will take
the raw data and construct an appropriate TCP packet or sequence of TCP
packets that will transport the raw data to its destination.  At the
destination, the TCP packet(s) are analyzed to reconstruct the raw data.

In this packet construction stage, it is possible that a sequence of data
may be aggregated into a single TCP packet, but it is also possible that
the data may be broken down into multiple TCP packets.

> UDP is a connectionless protocol --

Yes.

> real time applications use it to send
> keystrokes (for telnet sessions),

No, telnet uses TCP.

> audio information (you can lose some of it
> and it's OK, but you need the low overhead of UDP to minimize delay and make
> it isochronous), and gaming information like periodic updates from Netrek or
> Xpilot servers.

Yes.

> If you want aggregation with UDP, you need to do it
> explicitly yourself, so Netrek does it explicitly, i.e. in its own source
> code.  

Not exactly.  Both TCP and UDP do packet level aggregation when assembling
packets from raw data.  This was the point of Trent's earlier email.

The high level message aggregation can be done both under TCP and UDP.
In fact, Netrek supports both TCP and UDP modes.

-- 
Dave Ahn <ahn@vec.wfubmc.edu>        |  "When you were born, you cried and the
                                     |  world rejoiced.  Try to live your life
Virtual Endoscopy Center             |  so that when you die, you will rejoice
Wake Forest Univ. School of Medicine |  and the world will cry."  -1/2 jj^2