NAME

       SOAP::Trace - used only to manage and manipulate the runtime tracing of execution within
       the toolkit

DESCRIPTION

       This class has no methods or objects. It is used only to manage and manipulate the runtime
       tracing of execution within the toolkit. In absence of methods, this section reviews the
       events that may be configured and the ways of configuring them.

SYNOPSIS

       Tracing is enabled by the SOAP::Lite import method. This is usually done at compile-time,
       though it may be done explicitly by calling import directly. The commands for setting up
       tracing start with the keyword +trace. Alternately, +debug may be used; the two are
       interchangeable. After the initial keyword, one or more of the signals detailed here may
       be specified, optionally with a callback to handle them. When specifying multiple signals
       to be handled by a single callback, it is sufficient to list all of them first, followed
       finally by the callback, as in:

          use SOAP::Lite +trace =>
            method => fault => \&message_level,
            trace => objects => \&lower_level;

       In the fragment, the reference to message_level is installed as the callback for both
       method and fault signals, while lower_level is installed for trace and object events. If
       callbacks aren't explicitly provided, the default tracing action is to log a message to
       Perl's STDOUT file descriptor. Callbacks should expect a one or more arguments passed in,
       though the nature of the arguments varies based on the signal.

       Any signal can be disabled by prefacing the name with a hyphen, such as -result. This is
       useful with the pseudosignal "all," which is shorthand for the full list of signals. The
       following fragment disables only the two signals, while still enabling the rest:

           SOAP::Lite->import(+trace => all => -result => -parameters);

       If the keyword +trace (or +debug) is used without any signals specified, it enables all
       signals (as if all were implied).

       The signals and their meaning follow. Each also bears a note as to whether the signal is
       relevant to a server application, client application, or both.

TRACE SIGNALS

       transport Client only
           Triggered in the transport layer just before a request is sent and immediately after a
           response is received. Each time the signal is sent, the sole argument to the callback
           is the relevant object. On requests, this is a HTTP::Request object; for responses,
           it's a HTTP::Response object.

       dispatch Server only
           Triggered with the full name of the method being dispatched, just before execution is
           passed to it. It is currently disabled in SOAP::Lite 0.55.

       result Server only
           Triggered after the method has been dispatched and is passed the results returned from
           the method as a list. The result values have not yet been serialized when this signal
           is sent.

       parameters Server only
           Triggered before a method call is actually dispatched, with the data that is intended
           for the call itself. The parameters for the method call are passed in as a list, after
           having been deserialized into Perl data.

       headers Server only
           This signal should be for triggering on the headers of an incoming message, but it
           isn't implemented as of SOAP::Lite 0.55.

       objects Client or server
           Highlights when an object is instantiated or destroyed. It is triggered in the new and
           DESTROY methods of the various SOAP::Lite classes.

       method Client or server
           Triggered with the list of arguments whenever the envelope method of SOAP::Serializer
           is invoked with an initial argument of method. The initial string itself isn't passed
           to the callback.

       fault Client or server
           As with the method signal earlier, except that this signal is triggered when
           SOAP::Serializer::envelope is called with an initial argument of fault.

       freeform Client or server
           Like the two previous, this signal is triggered when the method
           SOAP::Serializer::envelope is called with an initial parameter of freeform. This
           syntax is used when the method is creating SOAP::Data objects from free-form input
           data.

       trace Client or server
           Triggered at the entry-point of many of the more-significant functions. Not all the
           functions within the SOAP::Lite classes trigger this signal. Those that do are
           primarily the highly visible functions described in the interface descriptions for the
           various classes.

       debug Client or server
           Used in the various transport modules to track the contents of requests and responses
           (as ordinary strings, not as objects) at different points along the way.

EXAMPLES

   SELECTING SIGNALS TO TRACE
       The following code snippet will enable tracing for all signals:

         use SOAP::Lite +trace => 'all';

       You can disable tracing for a set of signals by prefixing the signal name with a hyphen.
       Therefore, if you wish to enable tracing for every signal EXCEPT transport signals, then
       you would use the code below:

         use SOAP::Lite +trace => [ qw(all -transport) ];

   LOGGING SIGNALS TO A FILE
       You can optionally provide a subroutine or callback to each signal trace you declare. Each
       time a signal is received, it is passed to the corresponding subroutine. For example, the
       following code effectively logs all fault signals to a file called fault.log:

         use SOAP::Lite +trace => [ fault => \&log_faults ];

         sub log_faults {
           open LOGFILE,">fault.log";
           print LOGFILE, $_[0] . "\n";
           close LOGFILE;
         }

       You can also use a single callback for multiple signals using the code below:

         use SOAP::Lite +trace => [ method, fault => \&log ];

   LOGGING MESSAGE CONTENTS
       The transport signal is unique in the that the signal is not a text string, but the
       actually HTTP::Request being sent (just prior to be sent), or HTTP::Response object
       (immediately after it was received). The following code sample shows how to make use of
       this:

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

         sub log_message {
           my ($in) = @_;
           if (class($in) eq "HTTP::Request") {
             # do something...
             print $in->contents; # ...for example
           } elsif (class($in) eq "HTTP::Response") {
             # do something
           }
         }

   ON_DEBUG
       The "on_debug" method is available, as in:

         use SOAP::Lite;
         my $client = SOAP::Lite
           ->uri($NS)
           ->proxy($HOST)
           ->on_debug( sub { print @_; } );

ACKNOWLEDGEMENTS

       Special thanks to O'Reilly publishing which has graciously allowed SOAP::Lite to republish
       and redistribute large excerpts from Programming Web Services with Perl, mainly the
       SOAP::Lite reference found in Appendix B.

COPYRIGHT

       Copyright (C) 2000-2004 Paul Kulchenko. All rights reserved.

       This library is free software; you can redistribute it and/or modify it under the same
       terms as Perl itself.

AUTHORS

       Paul Kulchenko (paulclinger@yahoo.com)

       Randy J. Ray (rjray@blackperl.com)

       Byrne Reese (byrne@majordojo.com)