Subject:
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Re: rcxhttpd?
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Newsgroups:
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lugnet.robotics.rcx
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Date:
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Wed, 21 Jul 1999 05:28:40 GMT
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Viewed:
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1727 times
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I don't think my first post succeeded, so here it is again. Sorry if you've
already seen this.
Matthew Miller wrote:
>
> Todd Lehman <lehman@javanet.com> wrote:
> > What about other TCP protocols? Wouldn't it be fun to ftp or telnet to
> > your RCX brick? (Just because you can? :-)
>
> Don't forget 'finger'. There's already provisions for vending machines, so
> it's not much of a stretch. :)
>
> --
> Matthew Miller ---> mattdm@mattdm.org
> Quotes 'R' Us ---> http://quotes-r-us.org/
Why not SMTP (E-mail)? Then we could IR an E-mail to a 'bot, who could
wander around the house until it finds another 'bot. Then it would relay
the message to that 'bot. This second 'bot could wander around until
finding another 'bot, or an active IR tower, etc. until the E-mail
finally gets delivered to the target 'bot or PC ;-)
More seriously,
a) all these protocols (HTTPD, FTP, etc) assume an underlying IP protocol.
Many of them (telnet and FTP, for example) conventionally require TCP
on top of the IP protocol. UDP, while less reliable, would be smaller
and easier to implement than TCP. On the other hand, given the unreliability of
the IR communication, the error detection and correction in TCP might be
attractive.
b) having the IP protocol assumes an underlying media layer protocol
(sorry, net gods, but I can't recall the actual OSI reference model name
for this layer). This function would be served by the proposed Lego
Network Protocol.
c) I don't see much advantage to any of this if your RCX ONLY
communicates with a host PC. The benefits appear when your RCX exists in
a COMMUNITY of other devices which are capable of communicating with the
RCX. Then the RCX must be able to perform fundamental network functions
such as answer questions like: who are you? do you have information for
me? can I deliver information to X via you? (Oh no, that sounds like a
conversation between two E-mail (SMTP) servers!).
d) In the above COMMUNITY situation,
1) HTTPD would be handy when the 'bot must deliver information
already formatted for human eyes. For example, if your RCX is outside
the window monitoring the weather, and you want to see a weather report.
2) but TFTP (trivial file transfer protocol) would be better for
plain old information dumping. It could probably be just layered over
the existing RCX datalogs.
2a) FTP would probably just add bulk to TFTP, unless you need
security, reliability or hierarchical data retrieval.
3) FINGER would be handy, not just for answering the "who are you?"
question, but for communicating status or any relatively short message.
This requires that your COMMUNITY agree on the structure and meaning of
the FINGER responses.
4) For the life of me, I can't see any advantage telnet would have
over just opening at 2400bps terminal session with your 'bot.
5) (again with the SMTP). SMTP was designed with consideration for
low-powered devices in mind, and as such shouldn't be hard to implement.
(But where would you *store* messages?) SMTP (and E-mail in general) is
a "store and forward" protocol: messages are received and stored until
they can be re-transmitted closer to their destination. All my ideas for
using this involve a COMMUNITY larger than any yet proposed on this
list (I'm thinking of honey bees, espionage networks,...). Wait, I just
thought of a use: a 'bot with SMTP could communicate directly with the
lugnet.robotics.rcx list/newsgroup! Think of it! Your own 'bot could
monitor the list for postings written by its creator, and when it saw words
like "rebuild" or "scrap", it could find a dark corner to hide in! Or worse,
you could get flamed by your own creation! (Now aren't you glad you read
this whole posting :-)
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Message has 1 Reply:
 | | Re: rcxhttpd?
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| (...) LOL! I like it! (...) [other protocols snipped] (...) Yes I am! Now, to convince the department that we _really_ need 1000 more Mindstorm kits as a fall-back for e-mail in case the net goes down. ;) jack (envisioning a building full of roving (...) (25 years ago, 21-Jul-99, to lugnet.robotics.rcx)
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Message is in Reply To:
| | Re: rcxhttpd?
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| (...) Since the RCX has essentially a serial interface to the outside world, you would need to encode and decode the HTTP requests and responses into a serial-based protocol. If you actually wanted the RCX to be plug-and-play compatible with (...) (25 years ago, 19-Jul-99, to lugnet.robotics.rcx)
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