Rheinmetall open-sources its military hardware communication protocol

German defense giant Rheinmetall just published the communication protocol for its Battlesuite military platform on GitHub.

The company released documentation and code for onboardapi, a middleware library designed to connect sensor systems and software on tactical hardware. Built on the ddkit software development kit, it uses the Data Distribution Service (DDS) standard by the Object Management Group. The library relies on a publish-subscribe architecture for low-latency data exchange. The core interface is written in C++, with official wrappers for Python, Java, and C# / .NET.

Why it matters: Defense contractors almost never expose their hardware APIs to the public. Rheinmetall released the interface descriptions under the open-source Eclipse Public License (EPL v2.0), making it easier for external software to talk to their hardware. The runtime libraries themselves remain under a proprietary license.

Know this: The protocol uses DDS XTypes and XCDR2 encoding to preserve backward compatibility. That means different versions of software components can talk to each other even after the underlying data models update.

Writing code for military hardware just got a little more public.