RU Full Stream Ahead: Breaking the protocol barrier with http4k Ivan Sanchez, Kotlin Conf 2025

Recording brought to you by American Express. HTTP s requestresponse pattern has served us well, but modern web applications demand more. Realtime communication demands different protocols, yet maintaining testability and simplicity remains crucial to developer experience. In this talk, we ll explore how http4k extends HTTP s capabilities through WebSocket and ServerSent Events support and how these protocols can be modelled as simple functions, making them as testable as plain HTTP endpoints. We ll then show how these streaming capabilities open up new possibilities for serverside rendering, bringing us full circle from the days of JSP to modern reactive interfaces all while keeping the complexity on the server where it belongs. Join us to discover how http4k s streaming capabilities can enhance your web applications, enabling everything from chat applications to live dashboards and reactive serverrendered interfaces.