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event driven protocol module interface

LWP::Conn - event driven protocol module interface


LWP::Conn - event driven protocol module interface


  use LWP::Conn::XXX;

  $conn = LWP::Conn::XXX->new(ManagedBy => $mgr,

                              Host      => $host,

                              Port      => $port,




The LWP::Conn objects represent a connection to some server where one or more request/response exchanges can take place. There are different subclasses for various types of the underlying (network) protocols. (Talking about 'subclasses' is kind of a lie, since the base-class does not really manifest itself as any real code.)

LWP::Conn objects conform to the following interfaces when interacting with their manager object (passed in as parameter during creation). For the normal setup, then manager will be a LWP::Server object.

An LWP::Conn object is contructed with the new() method. It takes hash-style arguments and the 'ManagedBy' parameter is the only which is mandatory for any LWP::Conn subclass. It should be an reference to the manager object that will get method callbacks when various events happen. Other parameters might be mandatory depending on the specific subclass.

  $conn = LWP::Conn::XXX->new(MangagedBy => $mgr,

                              Host => $host,

                              Port => $port,


The constructor will return a reference to the LWP::Conn object or undef. If a connection object is returned, then the manager should wait for callbacks methods to be invoked on itself. A return of undef will either indicate than we can't connect to the specified server or that all requests has already been processed. A manager can know the difference based on whether get_request() has been invoked on it or not.

The following methods are invoked by the created LWP::Conn object on their manager. The first two manage the request queue. The last three let the manager be made aware of the state of the connection.


  $mgr->pushback_request($conn, @requests);




The get_request() method should return a single LWP::Request object or undef if there are no more requests to process. It is passed a reference to the connection object as argument. If the connection objects discover that it has been too greedy (calling get_request() too many times), then it might want to return unprocessed request back to the mangager. It does so by calling the pushback_request() method with a reference to itself and one or more request objects as arguments. The first request obtained by get_request() should never be pushed back.

The following two methods can be invoked (usually by the manager) on a living $conn object. The activate() method can be invoked on a (usually 'idle') connection to make it start calling get_request() again. The stop() kills the connection (whatever state it is in).



When a connection has received a response, then it will invoke the following two methods on the request object (obtained using get_request()).

  $req->response_data($data, $res);


The response_data() method is invoked repeatedly as the body content of the response is received from the network. Invocation of this method is optional and depends on the kind of connection object this is. The response_done() method is always invoked once for each request obtained. It is called when the complete response has been received.


Copyright 1998, Gisle Aas

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