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calling Perl script from javascript

 
 
Richard Trahan
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      08-08-2004
I want a js function to call a Perl script residing on a server.
The Perl script will return a string, to be used by the js.
Pseudo code:
<script>
stringvar = perlfunc_on_server(stringarg)
document.write(stringvar)
</script>

Can stringvar above be a url?

The perlfunc_on_server could take the form of a GET,
like http://www.myserver.com/cgi-bin/perl...?arg=stringarg

Any other kludge is okay, as long as it works.

I'm very experienced with Perl, but a newbie to js.
Source code would help. Thanks.

 
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Erwin Moller
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      08-08-2004
Richard Trahan wrote:

> I want a js function to call a Perl script residing on a server.
> The Perl script will return a string, to be used by the js.
> Pseudo code:
> <script>
> stringvar = perlfunc_on_server(stringarg)
> document.write(stringvar)
> </script>
>
> Can stringvar above be a url?
>
> The perlfunc_on_server could take the form of a GET,
> like http://www.myserver.com/cgi-bin/perl...?arg=stringarg
>
> Any other kludge is okay, as long as it works.
>
> I'm very experienced with Perl, but a newbie to js.
> Source code would help. Thanks.


Hi,

If you need JS to get some interaction with a SERVERSIDE script, you have
to:
1) call that script
2) receive the response and do something usefull with it.

the easiest way is to use a hidden frame (or a new window, as long as you
have a window) in which you replace the URL with your call to the
Perlscript.
The Perlscript has to respond in a way that can be used in javascript.
In such situations I always let the server respond with a normal HTML-page
that has an onLoad-handler that call some javascript-function.
That function contains serverside information you need.

Eg (php example because my Perl sucks)

<html>
<head>
<script type="text/javascript">
function passInfo(){
alert("I received: <?= $_GET["userid"] ?>");
}
</script>
</head>
<body onLoad="passInfo();">
Leave this empty, not needed.
</body>
</html>

if you call the above page in some hidden frame it will respond with an
alert saying 'I received: 23':
example.php?userid=23

The $_GET example is lame of course, but you can just do all your serverside
Perlstuff over there.
Instead of the alert you can call some JS-function in your main-page,
possibly passing the needed info from the server.

Stuff you need to know to do this is:
1) how you make (hidden) frames. (frame and frameset)
2) replace the content of a window
top.frames["framename"].location = .......
3) how to make calls to a JS-function in another window.
top.frames["someFrameName"].someFunction(1,2,3);

Hope that helps.
Good luck,
Erwin Moller
 
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Martin Honnen
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      08-08-2004


Richard Trahan wrote:

> I want a js function to call a Perl script residing on a server.
> The Perl script will return a string, to be used by the js.
> Pseudo code:
> <script>
> stringvar = perlfunc_on_server(stringarg)
> document.write(stringvar)
> </script>


Well if you want to receive some text from the Perl script and display
it directly (document.write does that) I am not sure why you need
JavaScript at all, you could solve that on the server and use Perl to
read the text from the (other?) server and then include that in your
page with Perl.


> Can stringvar above be a url?


What you can do with HTML is
<script type="text/javascript"
src="www.myserver.com/cgi-bin/perlfunc_on_server.pl?arg=stringarg"></script>
that way you simply need to make sure your perlfunc_on_server.pl sets
the Content-Type to application/x-javascript and sends syntactically
correct JavaScript back.

> The perlfunc_on_server could take the form of a GET,
> like http://www.myserver.com/cgi-bin/perl...?arg=stringarg
>
> Any other kludge is okay, as long as it works.
>
> I'm very experienced with Perl, but a newbie to js.
> Source code would help.


The biggest problem could be the same origin policy governing
client-side scripting so while in theory in new browsers like Mozilla,
IE5+/Win, Safari you can make HTTP requests and receive the result you
can usually only connect back to the server the HTML page with the
script comes from.
See
http://www.faqts.com/knowledge_base/.../17226/fid/616
http://jibbering.com/2002/4/httprequest.html

There are also solutions using an iframe (usually a hidden one) to
perform the request to the server and returning some script that updates
the document containing the iframe but in this case too you are
restricted by the same origin policy.


--

Martin Honnen
http://JavaScript.FAQTs.com/

 
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Richard Trahan
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      08-08-2004
Thank you for your detailed reply.

Although a great idea, I cannot create an invisible frame
because the client window is an eBay ad. eBay software will
detect the frame creation code and delete the ad, as they
explicitly prohibit frames.

Is it true in general that js functions which take a string
argument will also take a url? I.e., can I do something like
alert(url(http://myserver.com)) ?

 
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Andre Herbst
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      08-08-2004
Richard Trahan wrote:

> Is it true in general that js functions which take a string
> argument will also take a url? I.e., can I do something like
> alert(url(http://myserver.com)) ?


This is partly true. Because an URL is also a string. You could call the
function:

alert("http://myserver.com")


 
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Richard Trahan
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      08-08-2004
Martin Honnen wrote:

Thank you for responding.

> What you can do with HTML is
> <script type="text/javascript"
> src="www.myserver.com/cgi-bin/perlfunc_on_server.pl?arg=stringarg"></script>
>
> that way you simply need to make sure your perlfunc_on_server.pl sets
> the Content-Type to application/x-javascript and sends syntactically
> correct JavaScript back.


That's exactly what I'm looking for. Thank you so much. I have not
been able to find a decent textbook or tutorial that explains exactly
how the various MIMEs are used in CGI programming.
The texts on network programming are all obsessed with
sockets, not CGI. Do you know of a good book?


 
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