SPI-17: Push an alert or information to resource users via a web interface

Executive Summary: 
A service provider pushes an alert or other information to a resource’s users via a web interface.
User Importance Summary: 
Service providers often need to notify resource users of time-critical information, such as impending system shutdown or status changes. These notifications need to be possible when resource users are interacting with the resource via web browsers.
Target Communities and Sizes: 
XSEDE service providers - 1 < N < 10 Independent resource providers - 10 < N < 100