使用浏览器从服务器提取消息来更新消息

Question

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.

What I am looking for is an architecture for solving this problem.

Technologies that I am using are .Net 4.5, ASP.Net MVC and KnockoutJs. Nodejs could be used, but I'd need to know the benefit of using nodejs over using SignalR.

My currently implementation is using a javascript timer which is polling the server every 30 seconds for new messages. It works, but the polling feels dirty.

Answer 1

Can't comment on ASP.NET - but have used Node.js together with Knockout for this. I have used both WebSockets (via socket.io library) and also Server Sent Events (SSE) to push updates to the client model.

Sounds like SSE would be a good fit in this case. The key is whatever your database technology is should support emitting changes events to your node middle-ware so that you can send this to the browser.

Answer 2

After more research, the polling method is the optimal solution for the technologies in involved.

The crux of the problem is there is no notification of a new message, which would prompt a change in the system. Currently, a new message is received when it is committed to the database. SQL Server does not have a notification mechanism (this is not 100 percent true, but it not a dependency I wish to take on). In long the run, the optimal system would be to implement a publisher/subscribe motel using SignalR or nodejs which would deliver real-time messages to the client. For this to happen it would require a complete re-architecture of the application.