Writing specific interfaces to communicate between the HMI and each low-level service is a costly—and likely unsustainable—proposal. A better approach is to use an HMI-agnostic, asynchronous messaging model such as Persistent Publish/Subscribe (PPS). A service for pushing out changes and receiving notifications, PPS provides a simple and effective way for the HMI to communicate with low-level componentst and the vehicle hardware.
Drawing on our experience building in-vehicle systems, we will describe how a PPS messaging model facilitates communication between an HTML5 HMI and low-level components.
With HTML5 becoming the HMI technology of choice, the problem facing system architects, then, is finding or devising a light-weight messaging model that bridges the gap between the HTML5 layer and disparate low-level components. Further, since a) many systems must be able to expand to include new devices and technologies, and b) many HMIs must accommodate applications using different HMI technologies, such as Elektrobit GUIDE and Qt, this messaging model must be open. That is, it must be able to integrate these new components and technologies, easily and efficiently.
To understand how PPS can simplify the design of embedded applications that