RE: Apache::DBI in startup.pl generating error
-Original Message- From: Rob Bloodgood [mailto:[EMAIL PROTECTED]] Sent: Thursday, August 02, 2001 2:31 PM To: Gunther Birznieks Cc: [EMAIL PROTECTED]; mod_perl Subject: RE: Apache::DBI in startup.pl generating error [snip] Well, it should be documented somewhere in the guide, or presumable in Apache::DBI.pod, that one should *only* PerlModule Apache::DBI Since it's pointless in startup.pl (right?). I think you need to think that one through a bit more :) --Geoff
RE: Apache::DBI in startup.pl generating error
Well, it should be documented somewhere in the guide, or
presumable in
Apache::DBI.pod, that one should *only*
PerlModule Apache::DBI
Since it's pointless in startup.pl (right?).
I think you need to think that one through a bit more :)
I disagree. I *did* think it through.
When involving Apache::DBI, one of two situations is true:
either you are
starting the webserver, or you are changing/testing startup.pl.
When starting the webserver, Apache::DBI loads and **transparently**
replaces the function of DBI-connect. If one were to NOT load
Apache::DBI, everything would work JUST THE SAME (codewise), but we
don't see the benefits that Apache::DBI provide.
true
When messing with startup.pl, Apache::DBI is redundant. Since it's
transparent, and only works when RUNNING the httpd,
nope - see below
it is undesired to have it in startup.pl, since it will only
cause errors.
I disagree with that - I do it all the time.
HOWEVER,
loading Apache::DBI as
httpd.conf:
PerlModule Apache::DBI
means that it only loads when it's worth loading, i.e. server
startup. If startup.pl then logically contains init code wrapped
in a test for whether it's running under mod_perl, within that
block becomes a good place for Apache::DBI specific
initialization.
So... your response indicates you think I missed something so
obvious that I would pick it up on a re-think. Well, this is my
original-think... have I really missed something?
ok, at least you're thinking :)
the two things I had in mind were:
a) generally, you ought to pre-load all your modules in startup.pl
so that you get the maximum amount of code-sharing/memory-sharing,
etc.
b) you couldn't call
Apache::DBI-connect_on_init;
without first
use Apache::DBI;
Except that (and I have to check this to be ABSOLUTELY shure but) PerlModule
Apache::DBI happens first, THEN startup.pl.
I just checked, and it works exactly that way when the httpd.conf directives
are in the following order:
PerlModule Apache::DBI
PerlRequire /etc/httpd/perl/lib/startup.pl
Since Apache::DBI is now loaded into the (single) perl interpreter's symbol
table, and since the above call to connect_on_init() is a method call (vs an
exported symbol), calling methods on it are valid, and can be easily wrapped
as I suggested in an if($ENV{MOD_PERL}) {} block. Explicitly, it is *NOT*
required to 'use Apache::DBI ();' in startup.pl to do this.
your *only* up top I thought was a bit strong, which was why I was trying
to
encourage deeper thought... for the most part, though, you get
Apache::DBI, which is more than be said for most...
I hope you found it constructive criticism and not condescending
- you seem like a person who wants to understand :)
Absolutely... I'm on this list to edify and to be edified.
L8r,
Rob
#!/usr/bin/perl -w
use Disclaimer qw/:standard/;
Re: Apache::DBI in startup.pl generating error
Alternatively, you can remove use Apache; from Apache::DBI and then you can test it perflectly fine from the command-line, you just won't be able to use connect_on_init() which is the only reason Apache::DBI seems to load Apache.pm (Apache.pm is causing your problem not Apache::DBI). At 10:20 PM 8/2/2001 +0800, Stas Bekman wrote: On Thu, 2 Aug 2001 [EMAIL PROTECTED] wrote: Thanks to all (esp Stas) for helping me with the 'make test' error involving CGI.pm. Here is the next issue: use Apache::DBI (); When I run perl -c startup.pl, I get the following error. I get NO error when I comment out the 'use Apache::DBI' line: Can't locate object method module via package Apache at /usr/lib/perl5/site_perl/5.005/Apache/DBI.pm line 202. BEGIN failed--compilation aborted at startup.pl line 8. Is there an earlier version of Apache::DBI I should be using (like the CGI.pm error)? It's not a problem. Apache::DBI expects mod_perl env, and hence you cannot test it from the command line. I suppose that you don't have a problem to start the server with Apache::DBI loaded. It's documented somewhere is the guide too. _ Stas Bekman JAm_pH -- Just Another mod_perl Hacker http://stason.org/ mod_perl Guide http://perl.apache.org/guide mailto:[EMAIL PROTECTED] http://apachetoday.com http://eXtropia.com/ http://singlesheaven.com http://perl.apache.org http://perlmonth.com/ __ Gunther Birznieks ([EMAIL PROTECTED]) eXtropia - The Open Web Technology Company http://www.eXtropia.com/
RE: Apache::DBI in startup.pl generating error
Except that (and I have to check this to be ABSOLUTELY shure but)
PerlModule
Apache::DBI happens first, THEN startup.pl.
only if you code it the way you did below, which isn't terribly portable.
see http://perl.apache.org/guide/perl.html#use_require_do_INC_and
basically, it's a bad programming practice not to use() modules in the code
that needs them. it works if you call PerlModule before you use() the
module, but again, it requires you to pay better attention to your
httpd.conf than you ought to.
consider writing an Apache module for CPAN, relying on, say, Apache::Log
calls, but failing to use Apache::Log in your module. If you have a
PerlModule Apache::Log everything works - until somebody else tries to run
your code with a different configuration. There's what works and then
there's how you ought to do things.
I just checked, and it works exactly that way when the httpd.conf
directives
are in the following order:
PerlModule Apache::DBI
PerlRequire/etc/httpd/perl/lib/startup.pl
Since Apache::DBI is now loaded into the (single) perl interpreter's
symbol
table, and since the above call to connect_on_init() is a method call
(vs an
exported symbol), calling methods on it are valid, and can be easily
wrapped
as I suggested in an if($ENV{MOD_PERL}) {} block. Explicitly, it is
*NOT*
required to 'use Apache::DBI ();' in startup.pl to do this.
this is just a particular gripe of mine, but I think we ought to be past the
$ENV{MOD_PERL} thing by now... startup.pl is a mod_perl idiom. if you are
designing web applications that depend on things like the mod_perl API,
Apache::DBI, and using the hooks into the Apache request cycle then you are
already way beyond making a startup.pl script portable between mod_perl and
other web environments.
--Geoff
RE: Apache::DBI in startup.pl generating error
-Original Message- From: Rob Bloodgood [mailto:[EMAIL PROTECTED]] Sent: Thursday, August 02, 2001 9:18 PM To: Geoffrey Young Cc: mod_perl Subject: RE: Apache::DBI in startup.pl generating error basically, it's a bad programming practice not to use() modules in the code that needs them. it works if you call PerlModule before you use() the module, but again, it requires you to pay better attention to your httpd.conf than you ought to. See my above point. Apache::DBI is *made* to be transparent, or at least semi-. It exists at the server level, and without (much) interaction with the programmer's dataspace at all. What better place for it than httpd.conf? And as for having to pay too much attention... well... let's just say that RedCode is spreading like it is because not enough IIS Admins paid better attention to the defaults THEY were given. :-) Seriously tho, why WOULDN'T you know what exactly is in your server configuration? well, I was going to leave this thread alone now, but I feel the need to justify myself on this one issue - I wrote that email a bit bleery-eyed... of course you need to know what your config contains. what I meant was that relying on the PerlModule syntax to allow you to call Apache::DBI-connect_on_init from your startup.pl was less than solid coding - it's the same as not use()ing modules from the scripts that require them (you didn't get that thought from what I wrote? I can't imagine why ;). as for the rest of Apache::DBI you're right, it's transparent so it doesn't matter where you load it - as long as you understand the action-at-a-distance concept, and are comfortable with it, you're ok... anyway, nuff said. Gunther and Ken tied things up nicely. --Geoff
RE: Apache::DBI in startup.pl generating error
Rob, how much stuff do you have in startup.pl? So nothing else is dependent
on Apache.pm modules?
To some degree, because Apache::DBI affects all the Perl interpreters in a
very config-type of way (as opposed to just preloading modules) I like the
idea of it being in PerlModule as it allows some servers to have caching
off and some servers to have it on yet still keep the application level
startup code in startup.pl.
I guess I've always considered startup.pl to be a place for dealing with
the various applications you are using and optimizing them by precaching
selected modules because you really need to use Perl code if you want to do
anything half way complex such as importing namespaces or creating global
singletons in a particular package space.
Whereas, something simple like Apache::DBI which turns on and off caching
seems just as well in PerlModule.
However, I also think that this is unworthy of inclusion into the guide.
PerlModule is well documented. startup.pl is well documented. Documenting
where to put Apache::DBI? That's up to the sysadmin. Doesn't seem worthy of
guide inclusion.
For the complaint about $ENV{MOD_PERL}. I am not quite sure I really agree
that this is a bad thing. Basically, by design you can see in your code
explicitly which code will be run when Mod_perl is running and which code
will not. What's so bad about that?
However, if you really have a problem with this, why don't you create
startup.pl and then a second non-apache-depdenent-startup.pl which is
require'd from startup.pl
Then when you run your script from the command line, just test the
non-apache-dependent-startup.pl being loaded first so that startup.pl only
contains mod_perl specific config. That way you get the best of both worlds.
You could also probably do a check on $INC{'Apache.pm'} or something like
that if you wanted to be a real stickler because in theory it might be
possible to bootstrap a pseudo Apache.pm for non-inside-Apache testing.
Anyway, in all these cases it does seem like there is more than one way to
do it, and advocating a specific way just doesn't seem right for the guide
since I think it is arguable either way.
Later,
Gunther
At 06:17 PM 8/2/2001 -0700, Rob Bloodgood wrote:
only if you code it the way you did below, which isn't terribly portable.
see http://perl.apache.org/guide/perl.html#use_require_do_INC_and
Ahem, PerlModule is a wrapper around the perl builtin require(). One
presumes that perl knows where it lives if perl can successfully require()
it. Especially since this module is installed into the standard perl
heirarchy as a system module, from CPAN. It's not even XS.
basically, it's a bad programming practice not to use() modules in the
code
that needs them. it works if you call PerlModule before you use() the
module, but again, it requires you to pay better attention to your
httpd.conf than you ought to.
See my above point. Apache::DBI is *made* to be transparent, or at least
semi-. It exists at the server level, and without (much) interaction with
the programmer's dataspace at all. What better place for it than
httpd.conf? And as for having to pay too much attention... well... let's
just say that RedCode is spreading like it is because not enough IIS Admins
paid better attention to the defaults THEY were given. :-) Seriously tho,
why WOULDN'T you know what exactly is in your server configuration?
consider writing an Apache module for CPAN, relying on, say, Apache::Log
calls, but failing to use Apache::Log in your module. If you have a
PerlModule Apache::Log everything works - until somebody else tries to run
your code with a different configuration. There's what works and then
there's how you ought to do things.
Again, server-level and mostly transparent. And as far as requiring a
module, 1) I would expect it to be clearly documented 2) and if I didn't
read the dox I deserve to have wasted the time, and 3) I'll leave 3 for
below...
methods on it are valid, and can be easily wrapped as I suggested
in an if($ENV{MOD_PERL}) {} block.
this is just a particular gripe of mine, but I think we ought to be
past the $ENV{MOD_PERL} thing by now... startup.pl is a mod_perl
idiom. if you are designing web applications that depend on things
like the mod_perl API, Apache::DBI, and using the hooks into the
Apache request cycle then you are already way beyond making a
startup.pl script portable between mod_perl and other web
environments.
Portable, portable, portable... First of all, understanding that items
appearing earlier or later in a config file is significant is so common I'm
astonished you consider it bad manners to see code that depends on it. And
unless I'm very badly mistaken, it's even significant in httpd.conf as far
as *Apache* is concerned.
And secondly, you're right, this is *mod_perl*. Not IIS, NSAPI, PHP, or
Cold Fusion. startup.pl is indubitably a mod_perl idiom. I'm failing
Re: Apache::DBI in startup.pl generating error
On Thu, 2 Aug 2001 [EMAIL PROTECTED] wrote: Thanks to all (esp Stas) for helping me with the 'make test' error involving CGI.pm. Here is the next issue: use Apache::DBI (); When I run perl -c startup.pl, I get the following error. I get NO error when I comment out the 'use Apache::DBI' line: Can't locate object method module via package Apache at /usr/lib/perl5/site_perl/5.005/Apache/DBI.pm line 202. BEGIN failed--compilation aborted at startup.pl line 8. Is there an earlier version of Apache::DBI I should be using (like the CGI.pm error)? It's not a problem. Apache::DBI expects mod_perl env, and hence you cannot test it from the command line. I suppose that you don't have a problem to start the server with Apache::DBI loaded. It's documented somewhere is the guide too. _ Stas Bekman JAm_pH -- Just Another mod_perl Hacker http://stason.org/ mod_perl Guide http://perl.apache.org/guide mailto:[EMAIL PROTECTED] http://apachetoday.com http://eXtropia.com/ http://singlesheaven.com http://perl.apache.org http://perlmonth.com/
RE: Apache::DBI in startup.pl generating error
only if you code it the way you did below, which isn't terribly portable.
see http://perl.apache.org/guide/perl.html#use_require_do_INC_and
Ahem, PerlModule is a wrapper around the perl builtin require(). One
presumes that perl knows where it lives if perl can successfully require()
it. Especially since this module is installed into the standard perl
heirarchy as a system module, from CPAN. It's not even XS.
basically, it's a bad programming practice not to use() modules in the
code
that needs them. it works if you call PerlModule before you use() the
module, but again, it requires you to pay better attention to your
httpd.conf than you ought to.
See my above point. Apache::DBI is *made* to be transparent, or at least
semi-. It exists at the server level, and without (much) interaction with
the programmer's dataspace at all. What better place for it than
httpd.conf? And as for having to pay too much attention... well... let's
just say that RedCode is spreading like it is because not enough IIS Admins
paid better attention to the defaults THEY were given. :-) Seriously tho,
why WOULDN'T you know what exactly is in your server configuration?
consider writing an Apache module for CPAN, relying on, say, Apache::Log
calls, but failing to use Apache::Log in your module. If you have a
PerlModule Apache::Log everything works - until somebody else tries to run
your code with a different configuration. There's what works and then
there's how you ought to do things.
Again, server-level and mostly transparent. And as far as requiring a
module, 1) I would expect it to be clearly documented 2) and if I didn't
read the dox I deserve to have wasted the time, and 3) I'll leave 3 for
below...
methods on it are valid, and can be easily wrapped as I suggested
in an if($ENV{MOD_PERL}) {} block.
this is just a particular gripe of mine, but I think we ought to be
past the $ENV{MOD_PERL} thing by now... startup.pl is a mod_perl
idiom. if you are designing web applications that depend on things
like the mod_perl API, Apache::DBI, and using the hooks into the
Apache request cycle then you are already way beyond making a
startup.pl script portable between mod_perl and other web
environments.
Portable, portable, portable... First of all, understanding that items
appearing earlier or later in a config file is significant is so common I'm
astonished you consider it bad manners to see code that depends on it. And
unless I'm very badly mistaken, it's even significant in httpd.conf as far
as *Apache* is concerned.
And secondly, you're right, this is *mod_perl*. Not IIS, NSAPI, PHP, or
Cold Fusion. startup.pl is indubitably a mod_perl idiom. I'm failing to
understand how this can be considered portable. But if you mean portable
from system to system, well, last I heard, ActiveState hadn't quite gotten
signals or sockets mastered, but I'm pretty certain the have the %ENV
emulation worked out.
But thirdly, I consider it a convenience to be able to test a script for
syntax errors before attempting to -HUP my webserver to see if it works or
not. perl -wc is done almost before I register the cursor moving. apache
restarts take me at least a minute. It's not about the request cycle, it's
about the DEBUG cycle. Since I didn't write Apache::DBI, but I have
reasonable confidence in the guy who did, it doesn't hurt my feelings to
defer initializing it until I've finished modifying startup.pl for other
reasons. Which means I can make a change, switch windows, and perl -wc and
get a syntax check, instead of an Apache error on Apache::AuthDBI, in under
10 seconds. Or even perl -w (even tho I run w/ -w in the shebang line and
PerlWarn On) and see debug output I'm working with.
For the record, I also consider it cheesy to have to check $ENV{MOD_PERL}
but to my knowledge, the Apache $s object isn't passed to startup.pl, and
setting an environment variable is significantly cheaper than creating a
perl object in terms of C code and devel/debug time. Remember, the E in
perl is for Eclectic. :-)
Idioms are there for a reason: They do well in shorthand a required task.
Even if there are other, longer ways to do the same thing. TIMTOWTDI. The
way I ought to program is in the way that makes perfect sense when one
understands all of the pieces, and document the hell out of it so that
people behind me who don't understand can at least follow the requirements
list. ESPECIALLY when the person behind me is me, 6 months later.
/rant
L8r,
Rob
#!/usr/bin/perl -w
use Disclaimer qw/:standard/;
