How is protobuf used in heron?

[dttlgotv]

In current code java protobuf 3.6.1 version is used.
And when I submit topo to yarn it seems that python use protobuf too which version is 3.6.1.

Anyone can tell me when a topo is submitted, how does protobuf is used?

[huijunwu]

protobuf mainly for the communication between tmaster <-> stmgr and stmgr<->instance. but it is also used in some other situations such as proto over http for tracker.