NAME

       "Tangence::Stream" - base class for "Tangence" stream-handling mixins

DESCRIPTION

       This module provides a base for Tangence::Client and Tangence::Server.  It is not intended
       to be used directly by "Tangence" implementation code.

       It provides the basic layer of message serialisation, deserialisation, and dispatching to
       methods that would handle the messages. Higher level classes are used to wrap this
       functionality, and provide implementations of methods to handle the messages received.

       When a message is received, it will be passed to a method whose name depends on the code
       of message received. The name will be "handle_request_", followed by the name of the
       message code, in uppercase; for example "handle_request_CALL".

REQUIRED METHODS

       The following methods are required to be implemented by some class using this mixin.

   tangence_write
          $stream->tangence_write( $data )

       Write bytes of data to the connected peer. $data will be a plain perl string.

   handle_request_$CODE
          $stream->handle_request_$CODE( $token, $message )

       Invoked on receipt of a given message code. $token will be some opaque perl scalar value,
       and $message will be an instance of Tangence::Message.

       The value of the token has no particular meaning, other than to be passed to the "respond"
       method.

PROVIDED METHODS

       The following methods are provided by this mixin.

   tangence_closed
          $stream->tangence_closed

       Informs the object that the underlying connection has now been closed, and any attachments
       to "Tangence::Object" or "Tangence::ObjectProxy" instances should now be dropped.

   tangence_readfrom
          $stream->tangence_readfrom( $buffer )

       Informs the object that more data has been read from the underlying connection stream.
       Whole messages will be removed from the beginning of the $buffer, which should be passed
       as a direct scalar (because it will be modified). This method will invoke the required
       "handle_request_*" methods. Any bytes remaining that form the start of a partial message
       will be left in the buffer.

   request
          $stream->request( %args )

       Serialises a message object to pass to the "tangence_write" method, then enqueues a
       response handler to be invoked when a reply arrives. Takes the following named arguments:

       request => Tangence::Message
               The message body

       on_response => CODE
               CODE reference to the callback to be invoked when a response to the message is
               received. It will be passed the response message:

                  $on_response->( $message )

   request (non-void)
          $response = $stream->request( request => $request )->get

       When called in non-void context, this method returns a Future that will yield the response
       instead. In this case it should not be given an "on_response" callback.

       In this form, a "MSG_ERROR" response will automatically turn into a failed Future; the
       subsequent "then" or "on_done" code will not have to handle this case.

   respond
          $stream->respond( $token, $message )

       Serialises a message object to be sent to the "tangence_write" method. The $token value
       that was passed to the "handle_request_" method ensures that it is sent at the correct
       position in the stream, to allow the peer to pair it with the corresponding request.

   minor_version
          $ver = $stream->minor_version

       Returns the minor version negotiated by the "MSG_INIT" / "MSG_INITED" initial message
       handshake.

AUTHOR

       Paul Evans <leonerd@leonerd.org.uk>