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############################################################################### |
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# |
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# This file copyright (c) 2001 by Randy J. Ray <rjray@blackperl.com>, |
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# all rights reserved |
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# |
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# Copying and distribution are permitted under the terms of the Artistic |
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# License as distributed with Perl versions 5.002 and later. See |
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# http://language.perl.com/misc/Artistic.html |
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# |
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############################################################################### |
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# |
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# $Id: Client.pm,v 1.6 2002/01/27 23:16:13 rjray Exp $ |
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# |
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# Description: This class implements an RPC::XML client, using LWP to |
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# manage the underlying communication protocols. It relies |
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# on the RPC::XML transaction core for data management. |
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# |
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# Functions: new |
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# send_request |
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# simple_request |
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# uri |
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# useragent |
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# request |
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# |
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# Libraries: LWP::UserAgent |
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# HTTP::Request |
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# URI |
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# RPC::XML |
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# |
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# Global Consts: $VERSION |
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# |
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############################################################################### |
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|
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package RPC::XML::Client; |
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|
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use 5.005; |
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use strict; |
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use vars qw($VERSION); |
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use subs qw(new simple_request send_request uri useragent request |
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fault_handler error_handler combined_handler); |
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|
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require LWP::UserAgent; |
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require HTTP::Request; |
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require URI; |
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|
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require RPC::XML; |
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require RPC::XML::Parser; |
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|
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$VERSION = do { my @r=(q$Revision: 1.6 $=~/\d+/g); sprintf "%d."."%02d"x$#r,@r }; |
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|
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1; |
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|
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############################################################################### |
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# |
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# Sub Name: new |
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# |
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# Description: Create a LWP::UA instance and add some extra material |
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# specific to our purposes. |
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# |
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# Arguments: NAME IN/OUT TYPE DESCRIPTION |
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# $class in scalar Class to bless into |
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# $location in scalar URI path for requests to go to |
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# %attrs in hash Extra info |
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# |
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# Globals: $VERSION |
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# |
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# Returns: Success: object reference |
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# Failure: error string |
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# |
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############################################################################### |
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sub new |
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{ |
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my $class = shift; |
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my $location = shift; |
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my %attrs = @_; |
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|
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$class = ref($class) || $class; |
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return "${class}::new: Missing location argument" unless $location; |
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|
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my ($self, $UA, $REQ, $PARSER); |
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|
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# Start by getting the LWP::UA object |
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$UA = LWP::UserAgent->new() or |
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return "${class}::new: Unable to get LWP::UserAgent object"; |
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$UA->agent(sprintf("%s/%s %s", $class, $VERSION, $UA->agent)); |
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$self->{__useragent} = $UA; |
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|
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# Next get the request object for later use |
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$REQ = HTTP::Request->new(POST => $location) or |
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return "${class}::new: Unable to get HTTP::Request object"; |
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$self->{__request} = $REQ; |
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$REQ->header(Content_Type => 'text/xml'); |
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|
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# Note and preserve any error or fault handlers. Check the combo-handler |
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# first, as it is superceded by anything more specific. |
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if (ref $attrs{combined_handler}) |
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{ |
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$self->{__error_cb} = $attrs{combined_handler}; |
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$self->{__fault_cb} = $attrs{combined_handler}; |
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delete $attrs{combined_handler}; |
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} |
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if (ref $attrs{fault_handler}) |
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{ |
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$self->{__fault_cb} = $attrs{fault_handler}; |
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delete $attrs{fault_handler}; |
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} |
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if (ref $attrs{error_handler}) |
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{ |
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$self->{__error_cb} = $attrs{error_handler}; |
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delete $attrs{error_handler}; |
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} |
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|
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# Preserve any remaining attributes passed in |
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$self->{$_} = $attrs{$_} for (keys %attrs); |
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|
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# Then, get the RPC::XML::Parser instance |
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$PARSER = RPC::XML::Parser->new() or |
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return "${class}::new: Unable to get RPC::XML::Parser object"; |
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$self->{__parser} = $PARSER; |
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|
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bless $self, $class; |
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} |
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|
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############################################################################### |
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# |
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# Sub Name: simple_request |
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# |
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# Description: Simplify the request process by both allowing for direct |
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# data on the incoming side, and for returning a native |
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# value rather than an object reference. |
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# |
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# Arguments: NAME IN/OUT TYPE DESCRIPTION |
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# $self in ref Class instance |
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# @args in list Various args -- see comments |
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# |
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# Globals: $RPC::XML::ERROR |
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# |
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# Returns: Success: value |
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# Failure: undef, error in $RPC::XML::ERROR |
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# |
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############################################################################### |
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sub simple_request |
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{ |
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my ($self, @args) = @_; |
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|
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my ($return, $value); |
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|
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$RPC::XML::ERROR = ''; |
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|
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$return = $self->send_request(@args); |
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unless (ref $return) |
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{ |
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$RPC::XML::ERROR = ref($self) . "::simple_request: $return"; |
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return undef; |
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} |
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$return->value; |
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} |
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|
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############################################################################### |
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# |
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# Sub Name: send_request |
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# |
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# Description: Take a RPC::XML::request object, dispatch a request, and |
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# parse the response. The return value should be a |
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# RPC::XML::response object, or an error string. |
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# |
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# Arguments: NAME IN/OUT TYPE DESCRIPTION |
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# $self in ref Class instance |
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# $req in ref RPC::XML::request object |
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# |
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# Returns: Success: RPC::XML::response object instance |
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# Failure: error string |
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# |
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############################################################################### |
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sub send_request |
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{ |
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my ($self, $req, @args) = @_; |
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|
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my ($me, $message, $response, $reqclone, $value); |
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|
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$me = ref($self) . ':send_request'; |
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|
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if (! UNIVERSAL::isa($req, 'RPC::XML::request')) |
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{ |
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# Assume that $req is the name of the routine to be called |
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$req = RPC::XML::request->new($req, @args); |
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return "$me: Error creating RPC::XML::request object: $RPC::XML::ERROR" |
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unless ($req); # $RPC::XML::ERROR is already set |
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} |
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|
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($reqclone = $self->{__request}->clone)->content($req->as_string); |
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$reqclone->header(Host => URI->new($reqclone->uri)->host); |
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$response = $self->{__useragent}->request($reqclone); |
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|
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unless ($response->is_success) |
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{ |
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$message = "$me: HTTP server error: " . $response->message; |
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return (ref($self->{__error_cb}) eq 'CODE') ? |
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$self->{__error_cb}->($message) : $message; |
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} |
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|
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# The return value from the parser's parse method no longer works as a |
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# direct return value for us |
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$value = $self->{__parser}->parse($response->content); |
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|
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# Rather, we now have to check if there is a callback in the case of |
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# errors or faults |
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if (! ref($value)) |
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{ |
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$message = "$me: parse-level error: $value"; |
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return (ref($self->{__error_cb}) eq 'CODE') ? |
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$self->{__error_cb}->($message) : $message; |
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} |
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elsif ($value->is_fault) |
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{ |
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return (ref($self->{__fault_cb}) eq 'CODE') ? |
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$self->{__fault_cb}->($value->value) : $value->value; |
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} |
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|
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$value->value; |
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} |
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|
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############################################################################### |
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# |
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# Sub Name: uri |
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# |
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# Description: Get or set the URI portion of the request |
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# |
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# Arguments: NAME IN/OUT TYPE DESCRIPTION |
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# $self in ref Object of this class |
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# $uri in scalar New URI, if passed |
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# |
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# Returns: Current URI, undef if trying to set an invalid URI |
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# |
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############################################################################### |
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sub uri |
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{ |
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$_[0]->{__request}->uri($_[1]); |
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} |
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|
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# Accessor methods for the LWP::UserAgent and HTTP::Request objects |
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sub useragent { $_[0]->{__useragent} } |
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sub request { $_[0]->{__request} } |
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|
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# These are get/set accessors for the fault-handler, error-handler and the |
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# combined fault/error handler. |
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sub fault_handler |
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{ |
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my ($self, $newval) = @_; |
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|
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my $val = $self->{__fault_cb}; |
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$self->{__fault_cb} = $newval if ($newval and ref($newval)); |
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# Special: an explicit undef is used to clear the callback |
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$self->{__fault_cb} = undef if (@_ == 2 and (! defined $newval)); |
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|
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$val; |
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} |
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sub error_handler |
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{ |
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my ($self, $newval) = @_; |
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|
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my $val = $self->{__error_cb}; |
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$self->{__error_cb} = $newval if ($newval and ref($newval)); |
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# Special: an explicit undef is used to clear the callback |
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$self->{__error_cb} = undef if (@_ == 2 and (! defined $newval)); |
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|
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$val; |
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} |
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sub combined_handler |
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{ |
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my ($self, $newval) = @_; |
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|
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($self->fault_handler($newval), $self->error_handler($newval)); |
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} |
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|
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__END__ |
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|
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=pod |
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|
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=head1 NAME |
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|
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RPC::XML::Client - An XML-RPC client class |
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|
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=head1 SYNOPSIS |
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|
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require RPC::XML; |
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require RPC::XML::Client; |
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|
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$cli = RPC::XML::Client->new('http://www.localhost.net/RPCSERV'); |
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$resp = $cli->send_request('system.listMethods'); |
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|
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print (ref $resp) ? join(', ', @{$resp->value}) : "Error: $resp"; |
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|
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=head1 DESCRIPTION |
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|
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This is an XML-RPC client built upon the B<RPC::XML> data classes, and using |
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B<LWP::UserAgent> and B<HTTP::Request> for the communication layer. This |
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client supports the full XML-RPC specification. |
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|
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=head1 METHODS |
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|
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The following methods are available: |
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|
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=over 4 |
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|
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=item new (URI [, ARGS]) |
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|
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Creates a new client object that will route its requests to the URL provided. |
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The constructor creates a B<HTTP::Request> object and a B<LWP::UserAgent> |
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object, which are stored on the client object. When requests are made, these |
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objects are ready to go, with the headers set appropriately. The return value |
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of this method is a reference to the new object. The C<URI> argument may be a |
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string or an object from the B<URI> class from CPAN. |
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|
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Any additional arguments are treated as key-value pairs. Most are attached to |
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the object itself without change. The following are recognized by C<new> and |
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treated specially: |
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|
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=over 8 |
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|
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=item error_handler |
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|
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If passed, the value must be a code reference that will be invoked when a |
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request results in a transport-level error. The closure will receive a |
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single argument, the text of the error message from the failed communication |
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attempt. It is expected to return a single value (assuming it returns at all). |
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|
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=item fault_handler |
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|
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If passed, the value must be a code reference. This one is invoked when a |
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request results in a fault response from the server. The closure will receive |
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a single argument, a B<RPC::XML::fault> instance that can be used to retrieve |
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the code and text-string of the fault. It is expected to return a single |
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value (if it returns at all). |
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|
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=item combined_handler |
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|
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If this parameter is specified, it too must have a code reference as a value. |
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It is installed as the handler for both faults and errors. Should either of |
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the other parameters be passed in addition to this one, they will take |
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precedence over this (more-specific wins out over less). As a combined |
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handler, the closure will get a string (non-reference) in cases of errors, and |
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an instance of B<RPC::XML::fault> in cases of faults. This allows the |
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developer to install a simple default handler, while later providing a more |
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specific one by means of the methods listed below. |
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|
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=back |
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|
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See the section on the effects of callbacks on return values, below. |
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|
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=item uri ([URI]) |
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|
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Returns the B<URI> that the invoking object is set to communicate with for |
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requests. If a string or C<URI> class object is passed as an argument, then |
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the URI is set to the new value. In either case, the pre-existing value is |
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returned. |
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|
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=item useragent |
| 359 |
|
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Returns the B<LWP::UserAgent> object instance stored on the client object. |
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It is not possible to assign a new such object, though direct access to it |
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should allow for any header modifications or other needed operations. |
| 363 |
|
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=item request |
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|
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Returns the B<HTTP::Request> object. As with the above, it is not allowed to |
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assign a new object, but access to this value should allow for any needed |
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operations. |
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|
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=item simple_request (ARGS) |
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|
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This is a somewhat friendlier wrapper around the next routine (C<send_request>) |
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that returns Perl-level data rather than an object reference. The arguments may |
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be the same as one would pass to the B<RPC::XML::request> constructor, or there |
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may be a single request object as an argument. The return value will be a |
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native Perl value. If the return value is C<undef>, an error has occurred and |
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C<simple_request> has placed the error message in the global variable |
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C<B<$RPC::XML::ERROR>>. |
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|
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=item send_request (ARGS) |
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|
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Sends a request to the server and attempts to parse the returned data. The |
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argument may be an object of the B<RPC::XML::request> class, or it may be the |
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arguments to the constructor for the request class. The return value will be |
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either an error string or a data-type object. If the error encountered was a |
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run-time error within the RPC request itself, then the call will return a |
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C<RPC::XML::fault> value rather than an error string. |
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|
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If the return value from C<send_request> is not a reference, then it can only |
| 390 |
mean an error on the client-side (a local problem with the arguments and/or |
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syntax, or a transport problem). All data-type classes now support a method |
| 392 |
called C<is_fault> that may be easily used to determine if the "successful" |
| 393 |
return value is actually a C<RPC::XML::fault> without the need to use |
| 394 |
C<UNIVERSAL::ISA>. |
| 395 |
|
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=item error_handler([CODEREF]) |
| 397 |
|
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=item fault_handler([CODEREF]) |
| 399 |
|
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=item combined_handler([CODEREF]) |
| 401 |
|
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These accessor methods get (and possibly set, if CODEREF is passed) the |
| 403 |
specified callback/handler. The return value is always the current handler, |
| 404 |
even when setting a new one (allowing for later restoration, if desired). |
| 405 |
|
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=back |
| 407 |
|
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=head2 Callbacks and Return Values |
| 409 |
|
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If a callback is installed for errors or faults, it will be called before |
| 411 |
either of C<send_request> or C<simple_request> return. If the callback calls |
| 412 |
B<die> or otherwise interrupts execution, then there is no need to worry about |
| 413 |
the effect on return values. Otherwise, the return value of the callback |
| 414 |
becomes the return value of the original method (C<send_request> or |
| 415 |
C<simple_request>). Thus, all callbacks are expected, if they return at all, |
| 416 |
to return exactly one value. It is recommended that any callback return values |
| 417 |
conform to the expected return values. That is, an error callback would |
| 418 |
return a string, a fault callback would return the fault object. |
| 419 |
|
| 420 |
=head1 DIAGNOSTICS |
| 421 |
|
| 422 |
All methods return some type of reference on success, or an error string on |
| 423 |
failure. Non-reference return values should always be interpreted as errors, |
| 424 |
except in the case of C<simple_request>. |
| 425 |
|
| 426 |
=head1 CAVEATS |
| 427 |
|
| 428 |
This began as a reference implementation in which clarity of process and |
| 429 |
readability of the code took precedence over general efficiency. It is now |
| 430 |
being maintained as production code, but may still have parts that could be |
| 431 |
written more efficiently. |
| 432 |
|
| 433 |
=head1 CREDITS |
| 434 |
|
| 435 |
The B<XML-RPC> standard is Copyright (c) 1998-2001, UserLand Software, Inc. |
| 436 |
See <http://www.xmlrpc.com> for more information about the B<XML-RPC> |
| 437 |
specification. |
| 438 |
|
| 439 |
=head1 LICENSE |
| 440 |
|
| 441 |
This module is licensed under the terms of the Artistic License that covers |
| 442 |
Perl. See <http://language.perl.com/misc/Artistic.html> for the license |
| 443 |
itself. |
| 444 |
|
| 445 |
=head1 SEE ALSO |
| 446 |
|
| 447 |
L<RPC::XML>, L<RPC::XML::Server> |
| 448 |
|
| 449 |
=head1 AUTHOR |
| 450 |
|
| 451 |
Randy J. Ray <rjray@blackperl.com> |
| 452 |
|
| 453 |
=cut |
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