Common Alerting Protocol

The Common Alerting Protocol (CAP) is an XML-based data format for exchanging public warnings and emergencies between alerting technologies. CAP allows a warning message to be consistently disseminated simultaneously over many warning systems to many applications. CAP increases warning effectiveness and simplifies the task of activating a warning for responsible officials.

Individuals can receive standardized alerts from many sources and configure their applications to process and respond to the alerts as desired. Alerts from the United States Geological Survey, the Department of Homeland Security, NOAA and the California Office of Emergency Services can all be received in the same format, by the same application. That application can, for example, sound different alarms based on the information received.

By normalizing alert data across threats, jurisdictions and warning systems, CAP also can be used to detect trends and patterns in warning activity, such as trends that might indicate an undetected hazard or hostile act. From a procedural perspective, CAP reinforces a research-based template for effective warning message content and structure.

The CAP data structure is backward-compatible with existing alert formats including the Specific Area Message Encoding (SAME) used in Weatheradio and the broadcast Emergency Alert System, while adding capabilities including:
 * Flexible geographic targeting using latitude/longitude “boxes” and other geospatial representations in three dimensions;
 * Multilingual and multi-audience messaging;
 * Phased and delayed effective times and expirations;
 * Enhanced message update and cancellation features;
 * Template support for framing complete and effective warning messages;
 * Digital encryption and signature capability; and,
 * Facility for digital images, audio and video.

Background
The National Science and Technology Council (NSTC) report on “Effective Disaster Warnings” PDF (November, 2000) recommended that “a standard method should be developed to collect and relay instantaneously and automatically all types of hazard warnings and reports locally, regionally and nationally for input into a wide variety of dissemination systems.”

In 2001 an international, independent group of over 120 emergency managers began specifying and prototyping the Common Alerting Protocol data structure based on the recommendations of the NSTC report. The project was embraced by the non-profit Partnership for Public Warning and a number of international warning system vendors. A series of field trials and long-term demonstration projects during 2002-03 led to the submission of a draft CAP specification to the OASIS standards process for formalization.

The CAP 1.0 specification was approved by OASIS in April, 2004. Based on experience with CAP 1.0, the OASIS Emergency Management Technical Committee adopted an updated CAP 1.1 specification in October 2005. At a meeting in Geneva in October, 2006 the CAP 1.1 specification was taken under consideration by the International Telecommunications Union for adoption as an ITU recommendation.

Current Implementations
According to a CAP 1.0 Fact Sheet, CAP implementations have been demonstrated by agencies and companies including: United States Department of Homeland Security; National Weather Service; United States Geological Survey; California Office of Emergency Services; Virginia Department of Transportation; GeoDecisions, Inc.; NC4/E Team; Blue292; Warning Systems, Inc.; Comlabs, Inc.; mobileFoundations; Ship Analytics; MyStateUSA; IEM, Inc.; Hormann America, Inc.; SpectraRep, Inc; Oregon RAINS; Swan Island Networks, Inc.

It is also mentioned by the Internet Society in its 2005 "Public Warning Network Challenge".

During early 2005 the U.S. Department of Homeland Security (DHS), in partnership with the Association of Public Television Stations, demonstrated CAP-based "digital EAS" broadcasts over public television digital TV transmitters and satellite links in the Washington, D.C. area and nationwide.

CAP is the foundation technology for the proposed "Integrated Public Alert and Warning System," an all-hazard, all-media national warning architecture being developed by DHS, the National Weather Service and the Federal Communications Commission.

The Canadian government has adopted CAP for its CANALERT initiative and stakeholder groups are now working together to define a national profile for its implementation. CAP is also being implemented for a small-scale, grassroots hazard information system in Sri Lanka. This implementation is part of the "HazInfo Project" funded by Canada's International Development Research Centre.

In 2007, the International Telecommunications Union (ITU) adopted the Common Alerting Protocol as its recommendation X.1303.

Additional information
The CAP Cookbook is a wiki for developing and sharing implementation notes and other supplemental documentation for CAP.