Zeebe clients connect to brokers via a stateless gateway. For the communication between client and gateway gRPC is used. The communication protocol is defined using Protocol Buffers v3 (proto3), and you can find it in the Zeebe repository.
gRPC was first developed by Google and is now an open-source project and part of the Cloud Native Computing Foundation. If you’re new to gRPC, the “What is gRPC” page on the project website provides a good introduction to it.
gRPC has many nice features that make it a good fit for Zeebe:
- supports bi-directional streaming for opening a persistent connection and sending or receiving a stream of messages between client and server
- uses the common HTTP/2 protocol by default
- uses Protocol Buffers as an interface definition and data serialization mechanism–specifically, Zeebe uses proto3, which supports easy client generation in ten different programming languages
If there is no client in your target language yet, you can build your own client in a range of different programming languages.