Quarkus Community Call - 2026-07-08

[cescoffier]

The recording of the July 7th Quarkus Community Call is now available.

Recording: https://www.youtube.com/watch?v=3AVgGGxc5YY
Discussion notes: https://docs.google.com/document/d/1TgFZsuOQo9qZ4CnQII5LHhQVgMC6YsVMs1UJIAJooyM/edit?tab=t.0#heading=h.vsr1oshl0610

What We Covered

This session focused on JSON RPC and its role in the Quarkus ecosystem, presented by Phillip Kruger.

Quarkus 4 Quick Update

Clement shared a brief status update on Quarkus 4 development. The first beta is still on track for September 2026, and a detailed "state of development" post is being published on GitHub Discussions.

JSON RPC in Quarkus — Three Layers Deep

Phillip walked through the JSON RPC specification (a stateless, transport-agnostic RPC protocol from 2010) and then showed where Quarkus uses it today:

1. Dev UI — Under the covers, the Quarkus Dev UI uses JSON RPC over WebSocket to communicate between the browser and backend CDI beans. This is internal infrastructure, not a public API.

2. The quarkus-json-rpc extension — Extracted from the Dev UI, this extension lets you turn any CDI bean into a JSON RPC endpoint with a single @JsonRpcApi annotation. It handles build-time discovery, blocking/non-blocking execution, streaming via Multi, broadcasting, Open RPC schema generation, and even JavaScript client generation — so your Lit (or any JS) frontend can call backend methods with a simple import.

3. MCP (Model Context Protocol) — MCP is built on JSON RPC. The quarkus-mcp-server extension lets you annotate Java methods to define AI tools, resources, and prompts. Dev MCP goes further: it gives coding agents the same access a developer has through the Dev UI, using the exact same backend services.

Live Demo

Phillip demonstrated the full workflow: enabling the Dev UI JSON RPC log, adding the extension, creating endpoints with records and streaming, browsing the generated Open RPC schema, and using the generated JavaScript client in a Lit web component.

Discussion Highlights

• JSON RPC vs. JSONL — Max Rydahl Andersen and Clement discussed how JSON RPC (message structure) and JSONL (transmission format) are complementary, not competing.
• Naming conventions — The @JsonRpcApi casing doesn't match the spec's "JSON-RPC". Phillip will adjust this with backward compatibility.
• Future transports — HTTP transport support (testable with curl), HTTP/3 for long-lived connections, and WebTransport were discussed as future directions.
• Open RPC vs. AsyncAPI — Clement questioned whether AsyncAPI could be an alternative schema format. Phillip will research this.
• Jackson 3 — Migration should be straightforward once core Quarkus support lands.

Next Calls

• July 21: Website migration to Roq (Holly & Hundi)
• August: Summer break — no meetings
• September: HTTP/3 and Bazel support sessions (dates TBD)