An Extensible Markup Language (XML)-based protocol is utilized for communications between a Cellular Broadcast Entity (CBE) and a Cellular Broadcast Center (CBC) in a Commercial Mobile Alert System (CMAS) architecture. The CMAS architecture supports commercial mobile alerts, and the protocol provides a mechanism for Emergency Alert System (EAS) messages and related information to be communicated between the CBE and the CBC. In an example configuration, the protocol accommodates request messages from the CBE to the CBC and response messages from the CBC to the CBE. The request messages can provide an indication to initiate a message broadcast, update a previous message broadcast, or cancel a previous message broadcast. The response messages can provide an indication that the request message is valid, or an error message indicating that the request message is invalid.