gos_web_socket:
    server:
        port: 1337        #The port the socket server will listen on
        host: 127.0.0.1   #The host ip to bind to
        router:
           resources:
               - '%kernel.project_dir%/config/pubsub.yaml'
    topics:
        - "@app.topic.chat"

app_topic_chat:
    channel: 'app/chat/{first_user}/{second_user}'
    handler:
        callback: 'chat.topic' #related to the getName() of your topic
    requirements:
        first_user:
            pattern: 'd+' #accept all valid regex, don't put delimiters !
        second_user:
            pattern: 'd+'

!!  In DelegatingLoader.php line 37:
!!
!!    Cannot load resource "/var/www/html/cms/config/pubsub.yaml".