What is nexus? And where did it come from?

And while ownCloud has come a long way in the past seven years, the root problem has not gone away: we still keep metadata in sync in a request driven LAMP stack. On the server side, I needed a different language to allow ownCloud to use the pkcs11 stack to efficiently access an HSM. While I had a look at the different async php implementations, as well as, swoole I realized that the best bet would be a real systems language for the storage layer.

Source: central.owncloud.org