def main():    # 命令行参数解析，实际上命令行参数并没有使用    config.parse_args(sys.argv)    logging.setup("nova")    LOG = logging.getLogger(‘nova.all‘)    utils.monkey_patch()    objects.register_all()    launcher = service.process_launcher()    # 启动API以提供Rest服务，也就是nova-api（以WSGIService方式启动）    for api in CONF.enabled_apis:        try:            should_use_ssl = api in CONF.enabled_ssl_apis            server = service.WSGIService(api, use_ssl=should_use_ssl)            launcher.launch_service(server, workers=server.workers or 1)        except (Exception, SystemExit):            LOG.exception(_(‘Failed to load %s‘) % ‘%s-api‘ % api)    # 启动s3server（基于本地文件实现S3式的存储服务）    # 启动xvp_proxy(VNC代理，支持基于java的vnc客户端)    # 这两个服务都是以wsgi.Server方式启动    for mod in [s3server, xvp_proxy]:        try:            launcher.launch_service(mod.get_wsgi_server())        except (Exception, SystemExit):            LOG.exception(_(‘Failed to load %s‘) % mod.__name__)    # 其他的服务以Service方式启动    for binary in [‘nova-compute‘, ‘nova-network‘, ‘nova-scheduler‘,                   ‘nova-cert‘, ‘nova-conductor‘]:        # FIXME(sirp): Most service configs are defined in nova/service.py, but        # conductor has set a new precedent of storing these configs        # nova/<service>/api.py.        #        # We should update the existing services to use this new approach so we        # don‘t have to treat conductor differently here.        if binary == ‘nova-conductor‘:            topic = CONF.conductor.topic            manager = CONF.conductor.manager        else:            topic = None            manager = None        try:            launcher.launch_service(service.Service.create(binary=binary,                                                           topic=topic,                                                          manager=manager))        except (Exception, SystemExit):            LOG.exception(_(‘Failed to load %s‘), binary)    launcher.wait()