Protocols

Zeebe clients connect to brokers via a stateless gateway.

For the communication between client and gateway, a mix of REST and gRPC is used. The gRPC protocol is defined using Protocol Buffers v3 (proto3), and you can find it in the Zeebe repository. There, you will also find the OpenAPI v3 spec for the REST portion of the gateway API.

Note that while gRPC requires HTTP/2, the REST API can work with either HTTP/1.1 or HTTP/2.

What is gRPC?

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, see What is gRPC on the project website for an introduction.

Why gRPC?

gRPC has many beneficial features that make it a good fit for Zeebe, including:

• 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 client generation in ten different programming languages.

Supported clients

Currently, Zeebe officially supports two gRPC clients: one in Java, and one in Golang.

note

As of 8.5.0, the Go client does not support the REST API of the gateway.

Community clients have been created in other languages, including C#, Ruby, and JavaScript.

If there is no client in your target language yet, you can build your own client in a range of different programming languages.

Intercepting calls

Zeebe supports loading arbitrary gRPC server interceptors to intercept incoming calls.

note

As of 8.5.0, there is no interceptor or middleware functionality for the REST part of the client.