Location information interoperability of CAP and PIDF-LO for early warning systems

The Common Alerting Protocol (CAP) is an open standard, which is universally used for early warning systems and other emergency information systems. Future early warning systems will also disseminate CAP warning messages to location aware Internet devices, such as notebooks, Internet phones or Internet-enabled television sets. These Internet devices have the option to acquire their current location as a Presence Information Data Format – Location Object (PIDF-LO) document by the protocols and means developed by the Internet Engineering Task Force (IETF). When an Internet device receives a CAP message, determination of whether this alert is relevant to the user at the current location is crucial. However, the civic address format of PIDF-LO is not interoperable with CAP. This paper describes these interoperability issues, which were collected during a prototype implementation and proposes a mapping of PIDF-LO location elements to CAP to achieve interoperability.