Looks like a homegrown networking framework: https://github.com/twitter/heron/tree/master/heron/common/src/cpp/network https://github.com/twitter/heron/tree/ma

Looks like a homegrown networking framework: https://github.com/twitter/heron/tree/master/heron/common/src/cpp/network https://github.com/twitter/heron/tree/master/heron/common/sr... Their default event loop implementation uses libevent, and they're using protobuf in some of their higher-level networking classes, but the networking code itself seems to pretty much be plain sockets (with a thin portability layer on top in a few places).