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RE: Help with string concat and sockets
by merlyn (Sage) on May 17, 2000 at 02:34 UTC
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I usually get scared when I see people inventing a new TCP protocol. There are far too many things to worry about to do this right. If you need a simple RPC structure, just use HTTP as your protocol. Create your server with HTTP::Daemon, and your client then uses LWP::Simple or other parts of the LWP to handle the requests. The neat thing about this is a huge amount of code already provided, and when you need to slide to higher performance or proxying, you can use standard tools.
Do not invent a protocol. Just say no.
-- Randal L. Schwartz, Perl hacker | [reply] |
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Once upon a time, I had to write a suite of test programs for NNTP, HTTP, POP3, SMTP and FTP servers. I used perl because it was preferable to shell scripting, which was the way used prior to that (it only did simple SMTP and NNTP posting operations). The problem? The only system that could run these tests was a very unflexibly administered Solaris box with a very stripped install of Perl. Adding modules was strictly verboten, even in my home directory. I didn't even have IO::Socket to draw on. I reinvented four wheels, one axle, the concept of glass and I think power steering, but it got the job done and produced some very nice results. You never know when you're going to have to produce results without even 'standard' modules. And no, I never figured out why some modules were missing. They had been present once, the docs were still there, but even an extended probe with the find command didn't turn them up. 5-21-2000 : Fixed the typo in 'steering'
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Re: Help with string concat and sockets
by btrott (Parson) on May 17, 2000 at 01:57 UTC
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Jen--one quick idea I had is that perhaps your data has
control-M characters in it, which screw up the presentation
when you try to look at it in the print statement. I've
seen such characters make lines look pretty strange, in
the past.
To test this, you could try join-ing on a carriage
return ("\n"), just to see if this is indeed the problem.
If your data looks right, this could be it. In which case
you'll want to strip control-M characters:
tr/\cM//d;
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[d/l] |
Re: Help with string concat and sockets
by jen (Novice) on May 17, 2000 at 01:48 UTC
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Here is some more of the code, in case that's helpful.
# read the first line of the client's reply to determine which
# action to take
$action = <$client>;
chomp $action;
print "action is $action\n";
# set up the variable to match the end tag of the document
$endAction = $action;
$endAction =~ s/</<\//g;
# read the remainder of the client's reply
$testXML = "";
while (<$client>) {
chomp;
if ($_ eq $endAction) {
print "end found\n";
last;
} #endif
print "line: $_\n";
push @clientXML, $_;
$testXML = join '', $testXML, $_;
} # end while
print "testXML is $testXML\n\n";
And here is what the client is sending:
<FOO>
bla
bla
bla
blabababa
end
</FOO>
And here's the result of that print statement in the server:
endbababas bla
As you can see, the "testXML is" doesn't even show up except for that one "s"....
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Re: Help with string concat and sockets
by turnstep (Parson) on May 17, 2000 at 02:02 UTC
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Hard to say...could be some escape characters sneaking in. Try
making the test lines more unique, i.e.
bla1
abc
def
ghi
end
and stick a newline and a delimeter by replacing
$testXML = join '', $testXML, $_;
WITH
$testXML .= "**$_**\n";
and see if that helps to debug it at all...
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[d/l]
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Re: Help with string concat and sockets
by chromatic (Archbishop) on May 17, 2000 at 02:49 UTC
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Instead of using while on a filehandle, you might take advantage of the $/ operator in a block like this:
{
local $/; # undef input record separator
$clientRequest = <$client>; # slurp it all in
}
That'll get you the whole rest of the request in one go, instead of having to append a line at a time.
Jon Udell has a good example of building an HTTP server in Perl with the IO::Socket module, in his dhttp program. (But when I did the same thing, I used HTTP::Daemon.) | [reply]
[d/l] |
Re: Help with string concat and sockets
by jen (Novice) on May 18, 2000 at 22:31 UTC
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Thanks for all the help. Randal, unfortunately, my employer requires a new protocol, and that's what they're getting :)
The removal of \cM and concatenating with a \n instead of a blank string fixed the problem. Of course, now I'm on to bigger and worse problems, like segfaults - that's how it works though, right?
Jen | [reply] |