local database again for each resource its web socket clients are listening to in the above case just u201c widget u201d and determines if the content of that resource has changed since it was last sent to the client computer by comparing it with a hash of the previous content which it stored in its cache if it is changed the server computer transmits the new content to each client computer listening to the resource housing a slave database 150 on the server computer 125 or conversely placing the web server software on the database slave machine to leverage the replication capabilities of the database system provides a fully push based scalable web application solution the web application u201c listens u201d for triggers from the database master 155 to revalidate requests from clients that are connected persistently to the server computer 125 this configuration also offers a unifying model for discrete and persistent web services within this model activities on persistent connections e g websocket connections which begin with an http handshake map to certain conventional http operations a websocket connection to a uri in this case represents a persistent get request where the client receives updates to the state of the resource as they.