What you're talking about is known in web development
circles as CGI programming, and it's generally much
easier to do in Perl than in C or most other languages.
There are assorted ready-made modules available to
make it even easier still. For example, you might
want to look at CGI or CGI::Lite.
As far as Apache, that's good news: Apache is
generally very easy to work with. The first time I
ever played around with CGI programming, I downloaded
and installed Apache, configured it, wrote my Perl
script, and had it working all in one afternoon.
It wasn't the most elegant script ever (I was pretty
new to Perl at the time), but it worked.
Here's what you need to know, then...
- Your input will come either in the QUERY_STRING
environment variable (for GET requests) or on
standard input (for POST), but some characters
will be encoded (like %20 for space), so it is
generally easiest to retrieve the input using
a module, like CGI::Lite or CGI.
Some of us roll our own routines for this, but
that is a more involved exercise; given your
five-day deadline, you probably want to use a
module.
- Your script will be expected to print (on standard
output) the content to be sent to the browser; this
may include HTTP headers and MUST at least include
the Content-Type header. After the headers you
print a blank line, followed by your content (e.g.,
the HTML that the browser will show).
- If security is a concern, you should familiarize
yourself with Taint checking.
Here is a very minimal CGI script that you can
use to test your setup to see that it's working:
#!C:\wherever\Perl.exe
print "Content-type: text/html
<html><head><title>test</title></head>
<body><h1>It works.</h1></body></html>
";
update:
Other monks'
posts have made
me look again at
your request,
and I think maybe you wanted to get the
output from an external executable (written in C)
and send _that_ to the user. This also is quite
possible (maybe even easy, depending on how the
executable takes its input). In the trivial case
where the external program doesn't need any input
but only generates output, this will work:
#!C:\wherever\Perl.exe
open FOO, "C:\wherever\program.exe |";
# The | is a pipe; we're running program.exe and
# reading its output from the FOO filehandle:
print "Content-type: text/plain\n\n";
while (<FOO>) { print }
If the C script takes command-line arguments,
that the user needs to specify, then you'll
need to have an HTML form that lets the user
specify this input, and your Perl script will
take that input and massage it into command-line
arguments for the external program. You can insert
those arguments directly into the commandline, as
in,
open FOO, "C:\wherever\program.exe @args |";
If the
external program expects input in standard input,
then post a reply saying so and we'll go into how
to do that too.
It is also a good idea to make sure the program
in question can't do anything destructive that
you don't want, before turning loose a web
interface straight to it. If possible, you
should try to arrange for it to run as an
unprivileged user, but I don't know enough
about Windows 2000 to tell you how to do that.
If what the C program does is very simple, you
may want to just rewrite it in Perl.
$;=sub{$/};@;=map{my($a,$b)=($_,$;);$;=sub{$a.$b->()}}
split//,".rekcah lreP rehtona tsuJ";$\=$ ;->();print$/
| [reply]
[d/l]
[select] |
Yes, Perl can do this. The question is whether or not you can do this. You could try gathering the data from the form and passing it to the CGI script with backticks, the qx// operator, or a number of other possibilities. An alternative, if you know C, is to use Inline to hook Perl directly into the C code. Another possibility is to use cgic (or something similar), a CGI library written in C that you could simply link to the program and have everything handled in C.
If you have 5 days to figure this out, it shouldn't be too hard. Depending upon what you really need, this is really only a couple of hours worth of work, at most (for the first option or two). Heck, if the parameters are simple enough, it's a 10 minute job so you should have no problems getting it done. Good luck!
| [reply] |
Oh, does he want to still use the compiled C program
for generating the HTML? (jonadab rereads the original
post.) Huh, maybe he does. I was assuming he meant
he wanted to replace the C program with Perl, but upon
closer inspection I'm not at all sure that's the case.
$;=sub{$/};@;=map{my($a,$b)=($_,$;);$;=sub{$a.$b->()}}
split//,".rekcah lreP rehtona tsuJ";$\=$ ;->();print$/
| [reply]
[d/l] |
Perl will handle that job fine. Just make sure to carefully check the input you get from the client, as it's really easy to allow bad characters through. Be sure your Perl shabang (#!) line has the -T (taint) switch, which will force you to check your input before doing anything particularly dangerous with it (note that this won't stop you from doing dangerous things if you really try, but it will stop some common mistakes).
----
I wanted to explore how Perl's closures can be manipulated, and ended up creating an object system by accident.
-- Schemer
Note: All code is untested, unless otherwise stated
| [reply]
[d/l]
[select] |
Perl and the WWW? Perish the thought! ;-)
Perl has a long history of use with the web, including what you described.
You could definitely write a wrapper script in perl to do what you want - passing HTML form variables to the exe and scooping up the output and pushing to the browser, but then again you could do the whole thing with perl. It's flexible and powerful and a whole lot of pre-written code and examples await you.
| [reply] |
As you already have Apache, most of the hard work is already done for you. The module CGI.pm solves the rest of your worries, and all should work more or less together in the following, untested fashion:
#!perl -wT
use strict;
use CGI qw(fatalsToBrowser);
my $generator = 'c:/path/to/html/generator.exe';
my $filename = "c:/path/to/generated/html/page.html";
my $q = CGI->new();
my @generator_arguments;
# The parameter "start_page" must contain a number:
if ($q->param('start_page') =~ /^(\d+)$/) {
push @generator_arguments, "--page_start", $1;
};
# The parameter "text_string" must contain a string
# with only characters a-zA-Z and blank:
if ($q->param('text_string') =~ /^([a-zA-Z ])$/) {
push @generator_arguments, "--text_string", $1;
};
system($generator,@generator_arguments) == 0
or die "Couldn't start $generator: $! /$?";
# now read the generated HTML:
open HTML,"<",$filename
or die "Couldn't open $filename : $!";
my $html = do { local $/; <HTML> };
close HTML;
print CGI::header();
print $html;
perl -MHTTP::Daemon -MHTTP::Response -MLWP::Simple -e ' ; # The
$d = new HTTP::Daemon and fork and getprint $d->url and exit;#spider
($c = $d->accept())->get_request(); $c->send_response( new #in the
HTTP::Response(200,$_,$_,qq(Just another Perl hacker\n))); ' # web
| [reply]
[d/l]
[select] |
This should not be a problem in either Perl, or almost any
other language. I've a hard time coming up with a language
where this problem would not be a rather trivial task.
Abigail | [reply] |
Look into HTTP::Daemon, it saves you lots of time, as it does the basic tcp connection, handles http requests and responses, and even forms the basic http header for you.
One sentence, you can easily use it to make a simple web server.
See , this is perl, one module, fits most of your needs (in this case, almost all of your needs).
(Strike HTTP::Daemon part per jonadab's comment)
Oh, also use CGI module to help you generate the html you send back, if you don't want to worry about html formatting things.
| [reply] |
Look into HTTP::Daemon
This would be great advice if he were creating a
standalone web-serving app, but he specifically
mentions that he's using Apache, so he doesn't
need to handle any HTTP stuff at all, just take
the input Apache gives him and print content.
$;=sub{$/};@;=map{my($a,$b)=($_,$;);$;=sub{$a.$b->()}}
split//,".rekcah lreP rehtona tsuJ";$\=$ ;->();print$/
| [reply]
[d/l] |