Details
Major Description
It's clearly important for members of a cluster to communicate with one another.
Currently all communications between controller, participant, and spectator happens via zookeeper. This is important for systems where fault tolerance cannot be compromised and consensus is necessary. But this also increases the latency of communication quite a bit.
For some applications, it is important that communication between different components is fast, it's ok to lose messages in some cases or if controller fails after the message is sent. we can either use tcp or any other pub/sub mechanism to make this as faster.
Furthermore, members of the cluster may want to transfer larger amounts of data while still routing based on current Helix assignments. One way to do this is to wrap the current messaging API, but use a different underlying framework. Netty provides an efficient framework for intra-cluster communication and may be a good fit here.
The big thing is that we don't want ZooKeeper to turn into a data store, nor do we want it to be a place where there is high write traffic of any size. On top of that, not all applications need consensus for every piece of communication. This is why we need an alternative channel.
Programming language: Java
Experience required: Object-oriented programming, concurrency, possibly basic networking
Helpful knowledge: Helix API, ZooKeeper, frameworks like Netty