Tuesday, March 10, 2009

Adding http request/response logging to SOAP::Lite

Sometimes I just want to save the xml versions of the SOAP requests and responses (generally to share with someone else).

The SOAP::Lite perldoc page points to using SOAP::Trace. It has lots of good stuff but its a bit heavy. And in my case, I'm trying to figure out how to log response and requests over http so the following will hopefully help simplify my next search. :)

here is my approach, first the code (all good things start in code :) :
package SOAP::HTTP::Logging;

use warnings;
use strict;

use Exporter;

our @EXPORT = qw(
enable_logging
disable_logging
soap_log_file
log_message
);

our $logfile;
our $logboth = 0;
our $log_request = 0;
our $log_response = 0;

# setup global options
sub enable_logging { $log_request = $log_response = 1; }
sub disable_logging { $log_request = $log_response = 0; }
sub soap_log_file { $logfile = shift if @_; return $logfile; }

# logging sub
sub log_message {
my $in = shift; # SOAP::Lite pushes in the object its called on

# only log configured and enabled
return unless $logfile; # no logfile
return unless ref $in; # only handle objects
return unless $in->can('content'); # object must have content method

# only log if enabled
return unless $log_request or $log_response;

# make logfile more userfriendly
my $pre = "";

# decode prefix
$pre = ( ref $in eq 'HTTP::Request' ? 'Request' :
ref $in eq 'HTTP::Response' ? 'Response' :
'Unknown' );

# open logfile and write out information
open my $fh, '>>', $logfile
or return; ## sliently fail for now

printf $fh "%s [%d] %s: %s\n", scalar localtime, $$,
$pre, ( $in->content ? $in->content : 'N/A' );

close $fh;

## done
return;
}

1;
Well jezz, after copying that all over maybe that would be a good cpan module.

To use it, in the calling code add:
#!/usr/bin/perl

use strict;
use warnings;

use SOAP::HTTP::Logging;
use SOAP::Lite +trace => [
transport => &SOAP::HTTP::Logging::log_message
];

## ... somewhere before doing soap calls ...

# enable library logging
enable_logging();

# where to write log
soap_log_file( 'soap_transport.log' ); # might want a fullpath

# do your soap stuff
my $soap = SOAP::Lite->proxy( 'http://localhost' )->uri( '/Foo/Bar');
my $res = $soap->hi();

# disable logging some reason
disable_logging();

# different request
$res = $soap->login( $username, $password );

# log somewhere else
enable_logging();
soap_log_file( 'new_service_calls.log' );

$res = $soap->account_profile_2(); # a new version of calls

exit;
That's it. I can see several places to improve this code. (like better warnings on failure to open the file, better output formatting (or custom output formatting), xml tidy output, etc...

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