Javascript - Download/upload times w/bandwidth

Hi all,

I'm trying to come up with a script and I'm having a heck of a time...

I require users to enter the size (in MB or KB) of the attachment they
wish to transfer/upload. As they enter the number and move over to
the next field (using onBlur or...), I would like a popup/alert window
warning them that this attachment size would take "x" amount of time
based on a speed of 24 kilobits per second (kbps). If they are happy
with the amount of time, I wish to allow them to click OK (to carry on
with the transfer) or Cancel/No to cancel it.

Anyone can assist me on this? I find this is quite difficult and
would appreciate any assistance you could send my way.

Cheers
--P

re: Javascript - Download/upload times w/bandwidth

"- - Pierre" <casdev@canada.com> wrote in message
news:254e5e81.0310031004.1cd1f398@posting.google.c om...[color=blue]
> Hi all,
>
> I'm trying to come up with a script and I'm having a heck of a time...
>
> I require users to enter the size (in MB or KB) of the attachment they
> wish to transfer/upload. As they enter the number and move over to
> the next field (using onBlur or...), I would like a popup/alert window
> warning them that this attachment size would take "x" amount of time
> based on a speed of 24 kilobits per second (kbps). If they are happy
> with the amount of time, I wish to allow them to click OK (to carry on
> with the transfer) or Cancel/No to cancel it.
>
> Anyone can assist me on this? I find this is quite difficult and
> would appreciate any assistance you could send my way.
>
> Cheers
> --P[/color]
I don't have an answer for you - but I do know that pending the type of file
you want to download/upload, the results can differ - For example, a 500kb
txt file will transfer faster than a 500kb mp3, rm, jpg, gif or whatever
else type file.

This variation is not just due to filetype, but is in part related to the
browser and web server - I was told this (here) when working on streaming
media - I wanted to calculate the best streaming file to suggest to the
client pending their internet connection - and I thought I could do this by
timing a download of a small file.

I was told that because some browsers (and web surfers) support a
compression in tranzip similar to gzip that one might find on a unix/linux
box. Web Clients have headers that tell the web server what it is capable
of - If the web server is configured to compress it will do so automatically
for every web client that can support compression and some files (like
mp3/jpg/gif/streaming) have files that are already compressed and thus
further compression won't make much of a difference - whereas an html or txt
file will compress very well.

So - you can only guess the transfer times - but even then, some guesses can
vary tremendously - Also, when you think of it, if the web client is
reasonably modern and receiving a compressed file - it uncompresses it
automatically without user intervention and this requires client/computer
resources - which in itself can effect the 'download' time (ie the "save as"
dialog box will not have closed/completed until the full download has
finished.

So... I hope that gives you a rough idea - if you still want to give it a
try I'm sure someone here will offer some solution that might help in some
shape or form...

randell d.

re: Javascript - Download/upload times w/bandwidth

Thanks Randell. I appreciate the info. However, I simply need an
approximation. You see, my users will be coming "thru" a satellite
connection and I wish to give them an idea of the time it would take
prior to clicking "save and close" and using this very expensive
connection. Anyway, thanks again and hopefully someone has an idea.
Anyone of you JS gurus???

Ciao,

--Pierre


"Randell D." <you.can.email.me.at.randelld@yahoo.com> wrote in message news:<0q3gb.29216$pl3.26800@pd7tw3no>...[color=blue]
> "- - Pierre" <casdev@canada.com> wrote in message
> news:254e5e81.0310031004.1cd1f398@posting.google.c om...[color=green]
> > Hi all,
> >
> > I'm trying to come up with a script and I'm having a heck of a time...
> >
> > I require users to enter the size (in MB or KB) of the attachment they
> > wish to transfer/upload. As they enter the number and move over to
> > the next field (using onBlur or...), I would like a popup/alert window
> > warning them that this attachment size would take "x" amount of time
> > based on a speed of 24 kilobits per second (kbps). If they are happy
> > with the amount of time, I wish to allow them to click OK (to carry on
> > with the transfer) or Cancel/No to cancel it.
> >
> > Anyone can assist me on this? I find this is quite difficult and
> > would appreciate any assistance you could send my way.
> >
> > Cheers
> > --P[/color]
> I don't have an answer for you - but I do know that pending the type of file
> you want to download/upload, the results can differ - For example, a 500kb
> txt file will transfer faster than a 500kb mp3, rm, jpg, gif or whatever
> else type file.
>
> This variation is not just due to filetype, but is in part related to the
> browser and web server - I was told this (here) when working on streaming
> media - I wanted to calculate the best streaming file to suggest to the
> client pending their internet connection - and I thought I could do this by
> timing a download of a small file.
>
> I was told that because some browsers (and web surfers) support a
> compression in tranzip similar to gzip that one might find on a unix/linux
> box. Web Clients have headers that tell the web server what it is capable
> of - If the web server is configured to compress it will do so automatically
> for every web client that can support compression and some files (like
> mp3/jpg/gif/streaming) have files that are already compressed and thus
> further compression won't make much of a difference - whereas an html or txt
> file will compress very well.
>
> So - you can only guess the transfer times - but even then, some guesses can
> vary tremendously - Also, when you think of it, if the web client is
> reasonably modern and receiving a compressed file - it uncompresses it
> automatically without user intervention and this requires client/computer
> resources - which in itself can effect the 'download' time (ie the "save as"
> dialog box will not have closed/completed until the full download has
> finished.
>
> So... I hope that gives you a rough idea - if you still want to give it a
> try I'm sure someone here will offer some solution that might help in some
> shape or form...
>
> randell d.[/color]

re: Javascript - Download/upload times w/bandwidth

Sayeth Randell D. <you.can.email.me.at.randelld@yahoo.com>:[color=blue]
>
> I don't have an answer for you - but I do know that pending the type of file
> you want to download/upload, the results can differ - [...]
> I was told that because some browsers (and web surfers) support a
> compression in tranzip similar to gzip that one might find on a unix/linux
> box. [...] and some files (like
> mp3/jpg/gif/streaming) have files that are already compressed and thus
> further compression won't make much of a difference - whereas an html or txt
> file will compress very well.[/color]

Also, if your user is using a 56K modem, for example, there's all
sorts of data compression going on on the fly. And proxies to
confuse the situation. And if you just happen to be taking your
sample while they're downloading something else, or while someone
else sharing a cable with them is, or whatever ...

-----sharks

re: Javascript - Download/upload times w/bandwidth

casdev@canada.com (- - Pierre) wrote[color=blue]
> warning them that this attachment size would take "x" amount of time
> based on a speed of 24 kilobits per second (kbps). my users will be coming "thru" a satellite
> connection and I wish to give them an idea of the time it would take
> prior to clicking "save and close" and using this very expensive
> connection.[/color]

Not tested throughout, but this should provide some basic functionality:
<input type=text onchange="ask(this)">
<script>
function ask(el){
size=el.value.toLowerCase();
sizeno=el.value.replace(/\D/g,'');
if(size.indexOf('kb')+1){sizeno=sizeno*1024;}
if(size.indexOf('mb')+1){sizeno=sizeno*1024*1024;}
seconds=Math.round(sizeno*8/24/1000);
msg='At 24kbps, ' + size + ' would take '
+ minsec(seconds)
+ '.\nWould you like to continue?';
if(confirm(msg))
{}//they accept
else
{el.value='';el.focus();}
}
function minsec(s){
m=Math.floor(s/60);
s-=60*m;
if(m)m+=' minutes and ';
return m+s+' seconds';
}
</script>
HTH
Ivo
[color=blue]
> Ciao,
>
> --Pierre
>[/color]