[3250] in java-interest
Re: Some questions! Please help!
daemon@ATHENA.MIT.EDU (Brian Behlendorf)
Sat Nov 4 19:56:30 1995
Date: Sat, 4 Nov 1995 14:50:33 -0800 (PST)
From: Brian Behlendorf <brian@organic.com>
To: Gary Robinson <gary@post.acadia.net>
cc: java-interest@java.sun.com
In-Reply-To: <v0213050aacc09b3f0563@[205.217.210.19]>
On Fri, 3 Nov 1995, Gary Robinson wrote:
> For a business plan I'm working on this weekend for an upcoming meeting
> with a venture capitalist, I need answers to some questions.
Good, I hope you don't mind if I ask for some equity then in exchange for
these answers. :)
> 1) I need to send a stream of data which can be accessed simultaneously by
> a java applet running on thousands of computers. I can't afford the
> bandwidth to be in direct communication with each one. I understand there
> is something called "broadcasting" which somehow allows the data to go out
> over the Internet to a number of different locations at once. I think I
> heard that some "radio" experiments on the Internet have worked that way.
> My question is, is there some way I can do this with Java?
Not Java alone. This is a transport issue, outside the scope of Java.
There are a couple of mechanisms that act like "broadcasting" on the net
today
1) NNTP "flooding" (i.e. USENET news messages are copied and sent
to every other NNTP server)
2) Mbone "multicasting" (where IP packets are copied and distributed
between routers)
The latter isn't "real-time", the former is still largely the domain of
the academic community due to its bandwidth requirements. In addition,
several companies like RealAudio and Xing will soon be coming out with
redistribution technologies that perform essentially the same functions,
but their protocols have not been made public yet, and a network of such
redistributors would need to be set up before their use would be
justified.
> 2) When a user is browsing my Web site, I want a java applet to keep
> executing continuously as he moves from page to page -- I don't want to
> have it re-downloaded every time he changes pages. Is that possible?
If you mean is it possible to have an applet which creates its own window
for output to continue running when the page is changed, the answer is:
it's not specified by the API, it depends on the implementation. In the
current Netscape implementation, the answer is no, but there's no reason
to suspect they can't or won't change that. On the other hand, if you
have say a ticker-tape application which can take different starting
parameters on different pages... see my response below.
> 3) Is it possible for the applet I write to be downloaded to the user's
> hard disk so that it can be run later, during another session, without
> downloading it again?
The only model for that right now is local disk caching which most web
browsers do these days. I.e., when a resource is fetched, a copy is
saved to disk along with a time stamp, and when it's requested again the
client simply asks the server "has this resource been modified since
<time-stamp>", and if it hasn't, it uses the local cached copy. The
applet can even be called from other pages and in other contexts.
Brian
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