How to use the ovs.stream function in ovs

def do_listen(name):
    if sys.platform != 'win32' or (
            ovs.daemon._detach and ovs.daemon._detached):
        # On Windows the child is a new process created which should be the
        # one that creates the PassiveStream. Without this check, the new
        # child process will create a new PassiveStream overwriting the one
        # that the parent process created.
        error, pstream = ovs.stream.PassiveStream.open(name)
        if error:
            sys.stderr.write("could not listen on \"%s\": %s\n"
                             % (name, os.strerror(error)))
            sys.exit(1)

    ovs.daemon.daemonize()

    rpcs = []
    done = False
    while True:
        # Accept new connections.
        error, stream = pstream.accept()
        if stream:
            rpcs.append(ovs.jsonrpc.Connection(stream))
        elif error != errno.EAGAIN:
            sys.stderr.write("PassiveStream.accept() failed\n")

def main(argv):

    parser = argparse.ArgumentParser(
            description="JSON-RPC test utility for Python.",
            formatter_class=argparse.RawDescriptionHelpFormatter)

    commands = {"listen": (do_listen, 1),
                "request": (do_request, 3),
                "notify": (do_notify, 3),
                "help": (parser.print_help, (0,))}

    group_description = """\
listen LOCAL             listen for connections on LOCAL
request REMOTE METHOD PARAMS   send request, print reply
notify REMOTE METHOD PARAMS  send notification and exit
""" + ovs.stream.usage("JSON-RPC")

    group = parser.add_argument_group(title="Commands",
                                      description=group_description)
    group.add_argument('command', metavar="COMMAND", nargs=1,
                        choices=commands, help="Command to use.")
    group.add_argument('command_args', metavar="ARG", nargs='*',
                       help="Arguments to COMMAND.")

    ovs.daemon.add_args(parser)
    args = parser.parse_args()
    ovs.daemon.handle_args(args)

    command_name = args.command[0]
    args = args.command_args
    if command_name not in commands:
        sys.stderr.write("%s: unknown command \"%s\" "

def __connect(self):
        self.__disconnect()

        name = self.reconnect.get_name()
        if not self.reconnect.is_passive():
            error, self.stream = ovs.stream.Stream.open(name)
            if not error:
                self.reconnect.connecting(ovs.timeval.msec())
            else:
                self.reconnect.connect_failed(ovs.timeval.msec(), error)
        elif self.pstream is not None:
            error, self.pstream = ovs.stream.PassiveStream.open(name)
            if not error:
                self.reconnect.listening(ovs.timeval.msec())
            else:
                self.reconnect.connect_failed(ovs.timeval.msec(), error)

        self.seqno += 1

def create(path):
        assert isinstance(path, str)

        unix = "unix:%s" % ovs.util.abs_file_name(ovs.dirs.RUNDIR, path)
        error, stream = ovs.stream.Stream.open_block(
            ovs.stream.Stream.open(unix))

        if error:
            vlog.warn("failed to connect to %s" % path)
            return error, None

        return 0, UnixctlClient(ovs.jsonrpc.Connection(stream))

def _rpc_get_schema_json(self, database):
        LOG.debug('remote %s', self.remote)
        error, stream_ = stream.Stream.open_block(
            stream.Stream.open(self.remote))
        if error:
            vsctl_fatal('error %s' % os.strerror(error))
        rpc = jsonrpc.Connection(stream_)
        request = jsonrpc.Message.create_request('get_schema', [database])
        error, reply = rpc.transact_block(request)
        rpc.close()

        if error:
            vsctl_fatal(os.strerror(error))
        elif reply.error:
            vsctl_fatal('error %s' % reply.error)
        return reply.result

def run_command(self, args):
        _COMMANDS = {
            'list-dbs': self._list_dbs,
            'get-schema': self._get_schema,
            'get-schema-version': self._get_schema_version,
            'list-tables': self._list_tables,
            'list-columns': self._list_columns,
            'transact': self._transact,
            'monitor': self._monitor,
            'dump': self._dump,
        }

        command = args[0]
        args = args[1:]

        error, stream_ = stream.Stream.open_block(
            stream.Stream.open(self.remote))
        if error:
            raise RuntimeError('can not open socket to %s: %s' %
                               (self.remote, os.strerror(error)))
        rpc = jsonrpc.Connection(stream_)

        ret = _COMMANDS[command](rpc, *args)
        LOG.info('ret %s', ret)
        rpc.close()