Overview

Temporal applications communicate with the orchestrator — the Temporal Cluster. The worker process (running workflows) and the client process (invoking workflows) may be different processes running on different machines. While invoking workflows & activities may look like simple method invocation, it is a remote procedure call over the network. Therefore zio-temporal (and, under the hood, the Java SDK) serializes workflow & activity method parameters before sending them across the network.

ZIO-Temporal provides two ways to serialize data:

• As JSON objects using the zio-json library (default).
• In Protobuf binary format using the ScalaPB library (opt-in, via the zio-temporal-protobuf module).

The zio-json integration enforces serialization at compile time: a workflow or activity that returns or accepts a type without a ZTemporalCodec[T] in scope will not compile, with a precise error message pointing to the type that needs a codec. This eliminates a whole class of runtime bugs that the previous Jackson-based converter was prone to — most notably, types that silently serialized as empty JSON because a Scala module was not registered.

See zio-json serialization for the typical setup and ZTemporalCodec derivation.

See Protobuf serialization for the protobuf-flavoured setup.