使用浏览器更新消息从服务器中提取消息

I am tasked with creating a web page (think twitter) that updates when new messages are added to the database. When a message is removed from the database, it also must be removed from the client. It is possible that multiple clients can be accessing the same messages at the same time. Other actions can occur, such as a stop command issued on the server. Once this happens all the messages on the server will stop showing. I am tasked with creating a web page (think twi