  This paper presents a new framework, namely \emph{\onlay}, for scalable
asynchronous distributed systems. In this framework, we propose a consensus
protocol $L_{\phi}$, which is based on the Lachesis protocol~\cite{lachesis01}.
At the core of $L_{\phi}$ protocol, it introduces to use layering algorithm to
achieve practical Byzantine fault tolerance (pBFT) in leaderless asynchronous
Directed Acyclic Graph (DAG). Further, we present new online layering
algorithms for the evolutionary DAGs across the nodes. Our new protocol
achieves determistic scalable consensus in asynchronous pBFT by using assigned
layers and asynchronous partially ordered sets with logical time ordering
instead of blockchains. The partial ordering produced by $L_{\phi}$ is flexible
but consistent across the distributed system of nodes. We then present the
formal model of our layering-based consensus. The model is generalized that can
be applied to abstract asynchronous DAG-based distributed systems.
