Kevin L. Esteb

NAME

POE::Component::Client::Stomp::Utils - A set of utility routines for POE clients that wish to use a Message Queue server that understands the Stomp protocol.

SYNOPSIS

This module uses Net::Stomp::Frame to create frames for usage within POE based programs that wish to communicate to Message Queue servers.

DESCRIPTION

 Your program could use this module in the following fashion:

 use POE;
 use POE::Component::Client::Stomp;
 use POE::Component::Client::Stomp::Utils;

 my $stomp = POE::Component::Client::Stomp::Utils->new();
 my $frame = $stomp->connect({login => 'test', passcode => 'test'});
 $heap->{server}->put($frame);

The above examples creates a "CONNENCT" frame and sends it to the server. If the connection suceeds, the server will send back a "CONNECTION" frame. The handling of that frame is left up to your input handlers.

A Stomp frame consists of the following:

 COMMAND\012
 HEADERS\012
 BODY\000

Each command may have one or more headers. Some of those headers are optional. For the most part, the parameters passed to these methods are literal translations of what the protocol needs for each of the frame commands. This was done, because the protocol is described as being in flux, with a 1.0 version being available "real soon now".

So, NO ERROR checking is done. How the server will handle protocol errors is highly dependent on the servers implementation. For example, the server that I have been testing against, quietly dies. You have been warned...

No serialization of data is done within these routines. You will need to decide what serialiazarion is needed and perform that serialization before calling these methods. I have found the JSON is a light, and efficent serialization method. And just about every other lanaguage has a JSON implementation readily avaiable.

Some terminology issues. I am using the term "channel" to describe the communications pathway to named resources. The documentation for some of the vaious Message Queue servers, are using terms such "queue", "topic" and other nouns to describe the same thing.

METHODS

new

This method initializes the base object. It also creates internal storage for the session ID, the message ID and the transaction ID. If a transaction ID has been set, it will be automatically passed to those methods that require one.

Example
 $stomp = POE::Component::Client::Stomp::Utils->new();
connect

This method creates a "connect" frame. This frame is used to initiate a session with a Stomp server.

Example
 $frame = $stomp->connect({login => 'test', passcode => 'test'});
 $heap->{server}->put($frame);
disconnect

This method creates a "disconnect' frame. This framse is used to signal the server that you no longer wish to communicate with it.

Example
 $frame = $stomp->disconnect();
 $heap->{server}->put($frame);
subscribe

This method create a "subscribe" frame. This frame is used to notify the server which channels you want to listen too. The naming of channels is left up to the server implementation. When a message is available on requested channels, it will be sent your program.

     $frame = $stomp->subscribe({destination => '/queue/test', 
                                 ack => 'client'});
     $heap->{server}->put($frame);
unsubscribe

This method creates an "unsubscribe" frame. This frame is used to notify the server that you don't want to listen on that channel anymore. Subsequently any messages left on that channel will no longer be sent to your program.

     $frame = $stomp->unsubcribe({destination => 'test'});
     $heap->{server}->put($frame);
begin

This method creates a "begin" frame. This frame signals the server that a transaction is beginning. A transaction is either ended by a "commit" frame or an "abort" frame. Any other frame that is sent must have a transaction id associated with them. This is handled internally. The transaction id can be anything that makes sense to you.

Example
 $frame = $stomp->begin({transaction => '1234'});
 $heap->{server}->put($frame);

 $frame = $stomp->send({destination => 'test', 
                        data => 'this is my message'});
 $heap->{server}->put($frame);

 $frame = $stomp->commit();
 $heap->{server}->put($frame);
commit

This method creates a "commit" frame. This frame signals the end of a transaction. See the above example on usage.

abort

This method creates an "abort" frame. This frame is used to signal the server that the current transaction is to be aborted.

Example
 $frame = $stomp->abort();
 $heap->{server}->put($frame);
send

This method create a "send" frame. This frame is the basis of communication over your channel to the server.

Example
 $frame = $stomp->send({destination => 'test', 
                        data => 'this is my packet'});
 $heap->{server}->put($frame);

or

 $message = objToJson($data);
 $frame = $stomp->send({destination => 'test', 
                        data => $message, 
                        receipt => 'abcd'});
 $heap->{server}->put($frame);

 sub input_handler {
     my ($heap, $frame) = @_[HEAP, ARG0 ];

     if (($frame->command eq 'RECEIPT') and 
         ($frame->headers->{'receipt-id'} eq 'abcd')) {

         print "Message was seccessfully sent!\n";

     }

 }
ack

This method creates an "ack" frame. This frame is used to tell the server that the message was successfully received. It requires a message id.

Example
 $frame = $stomp->ack({'message-id' => '1234'});
 $heap->{server}->put($frame);

or

 sub input_handler {
     my ($heap, $frame) = @_[HEAP, ARG0];

     if ($frame->command eq 'MESSAGE') {

         $stomp->message_id($frame->headers->{'message-id'});
         $poe_kernel->post('test' => srv_message => $frame);

    }

 }

 sub srv_message {
     my ($heap, $frame) = @_[HEAP, ARG0];

     my $frame = $stomp->ack({'message-id' => $stomp->message_id});
     my $data = jsonToObj($frame->body);

     handle_data($data);
     $heap->{server}->put($frame);

 }

MUTATORS

transaction_id

This mutator will set/get the current transaction id. This transaction id will be used automatically in other methods that require this parameter when a transaction is in progress.

Example
 $trans_id = $stomp->transaction_id;
 $stomp->transaction_id('1234');
message_id

This mutator will set/get the current message id.

Example
 $msg_id = $stomp->message_id;
 $stomp->message_id('1234');
session_id

This mutator will get/set the session_id. The session id is set once upon initial connection to the server.

EXPORT

None by default.

SEE ALSO

 Net::Stomp
 Net::Stomp::Frame
 POE::Component::Client::Stomp

 http://stomp.codehaus.org/Protocol

AUTHOR

Kevin L. Esteb, <kesteb@wsipc.org>

COPYRIGHT AND LICENSE

Copyright (C) 2007 by Kevin L. Esteb

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.8.8 or, at your option, any later version of Perl 5 you may have available.

5 POD Errors

The following errors were encountered while parsing the POD:

Around line 293:

=over should be: '=over' or '=over positive_number'

Around line 307:

=over should be: '=over' or '=over positive_number'

Around line 431:

You forgot a '=back' before '=head1'

Around line 433:

'=item' outside of any '=over'

Around line 466:

You forgot a '=back' before '=head1'