My latest Internet Computing column, Server-Sent Events with Yaws (PDF), is now available. It discusses the fact that developers are increasingly building Web applications that rely on notifications from the server, such as updates from social networks, alerts from application monitors, or information from sensor networks. But given that HTTP is a request-response protocol, such notifications can be challenging, giving rise to techniques such as long polling and to entirely new protocols such as WebSocket. These challenges can be especially significant for mobile applications due to intermittent client connectivity and device battery-life issues. This column explores how the Yaws Web server, written in the Erlang programming language, supports the W3C Server-Sent Events notification approach.