The Open Messaging Interface (O-MI), an Open Group Internet of Things (IoT) Standard, fulfills the same purpose in the IoT Standards as HTTP does for the Internet. Typical examples of exchanged data are sensor readings, alarm or lifecycle events, requests for historical data, notifications about availability of new data, changes to existing data, etc. Just as HTTP can be used for transporting payloads in other formats as well as HTML, O-MI can be used for transporting payloads in almost any format. XML might currently be the most common text-based payload format but others, such as JSON, CSV, etc. may also be used. A defining characteristic of O-MI is that O-MI nodes do not have predefined roles, as it follows a peer-to-peer communications model.