Module managing the underlying network protocol(s) used by drb.

By default, drb uses the DRbTCPSocket protocol. Other protocols can be defined. A protocol must define the following class methods:

  [open(uri, config)] Open a client connection to the server at +uri+,
                      using configuration +config+.  Return a protocol
                      instance for this connection.
  [open_server(uri, config)] Open a server listening at +uri+,
                             using configuration +config+.  Return a
                             protocol instance for this listener.
  [uri_option(uri, config)] Take a URI, possibly containing an option
                            component (e.g. a trailing '?param=val'),
                            and return a [uri, option] tuple.

All of these methods should raise a DRbBadScheme error if the URI does not identify the protocol they support (e.g. "druby:" for the standard Ruby protocol). This is how the DRbProtocol module, given a URI, determines which protocol implementation serves that protocol.

The protocol instance returned by open_server must have the following methods:

accept

Accept a new connection to the server. Returns a protocol instance capable of communicating with the client.

close

Close the server connection.

uri

Get the URI for this server.

The protocol instance returned by open must have the following methods:

send_request (ref, msg_id, arg, b)

Send a request to ref with the given message id and arguments. This is most easily implemented by calling DRbMessage.send_request, providing a stream that sits on top of the current protocol.

recv_reply

Receive a reply from the server and return it as a [success-boolean, reply-value] pair. This is most easily implemented by calling DRb.recv_reply, providing a stream that sits on top of the current protocol.

alive?

Is this connection still alive?

close

Close this connection.

The protocol instance returned by open_server().accept() must have the following methods:

recv_request

Receive a request from the client and return a [object, message, args, block] tuple. This is most easily implemented by calling DRbMessage.recv_request, providing a stream that sits on top of the current protocol.

send_reply(succ, result)

Send a reply to the client. This is most easily implemented by calling DRbMessage.send_reply, providing a stream that sits on top of the current protocol.

close

Close this connection.

A new protocol is registered with the DRbProtocol module using the add_protocol method.

For examples of other protocols, see DRbUNIXSocket in drb/unix.rb, and HTTP0 in sample/http0.rb and sample/http0serv.rb in the full drb distribution.