  Matrix is a new message-oriented data synchronization middleware, used as a
federated platform for near real-time decentralized applications. It features a
novel approach for inter-server communication based on synchronizing message
history by using a replicated data structure. We measured the structure of
public parts in the Matrix federation as a basis to analyze the middleware's
scalability. We confirm that users are currently cumulated on a single large
server, but find more small servers than expected. We then analyze network load
distribution in the measured structure and identify scalability issues of
Matrix' group communication mechanism in structurally diverse federations.
