PDX public blockchain, based on PDX BaaP, introduces the concept of multi-chain “engine” at the architecture level. An “engine” can be as small as a distributed consensus algorithm, or as big as a full blockchain stack. For painless evolution, PDX blockchain simultaneously supports 4 categories of engines: “inactive” engine (0 to many), “transient” engine (0 or 1), “active” engine (1 or more) and “NexGen” engine (0 or 1). As PDX blockchain evolves, a new engine starts from “NexGen” status, then transitions to “active” engine after thorough in-field testing, then becomes “transient” waiting to be finally transited into “inactive”. The lifecycle of a blockchain engine, including its provisioning and de-provisioning, is managed by the “engine service” module in PDX blockchain