5. Data In, Data Out — JSON & MessagePack

Coming soon

This chapter is an outline. The full draft ships in a follow-up PR.

What this chapter will cover

Every service eats and produces data. This chapter covers how Uni turns bytes on the wire into Scala 3 case classes, and back, without per-type boilerplate.

Concepts introduced:

• JSON for parsing, mutation, and generation of JSON trees.
• Case-class codecs via Surface — no annotation or companion boilerplate required.
• When to reach for MessagePack instead of JSON (size, performance, binary-safe payloads).
• Streaming: parsing documents larger than memory, and producing them incrementally.
• Error handling: what happens when the bytes do not match the type.
• Interop with existing JSON libraries when you must speak someone else's schema.

Reference you can read now

• JSON Processing
• MessagePack
• Type Introspection (Surface)

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