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Solon v4.0.5 Released: WebSocket Ping/Pong, HTTP Client User-Agent Defaults, and More

#solon #java #backend #release

Solon v4.0.5 landed on August 12, 2026 — a small but practical release that touches networking, HTTP client behavior, serialization, and a few internals. Here's what changed and why it matters if you're building with Solon.

1. WebSocket heartbeat: sendPing() / sendPong()

The WebSocket API in solon-net now ships dedicated sendPing() and sendPong() methods, with matching adapters across the underlying server implementations.

If you've ever kept a WebSocket connection alive against a load balancer or a proxy with an idle timeout (nginx's proxy_read_timeout, for instance), you know the drill: without periodic control frames, the connection silently dies. Before, you had to build the ping frames yourself. Now it's a first-class call:

ws.sendPing();          // send a ping control frame
ws.sendPong();          // send a pong control frame
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For chat apps, dashboards, or any long-lived push channel, adding a heartbeat loop just got a lot simpler.

2. solon-net-httputils: a default User-Agent

HTTP clients built with solon-net-httputils now send a default User-Agent header — solon-http/<version> — so servers can identify your client without extra configuration.

It's fully configurable through HttpConfiguration:

// global override
HttpConfiguration.setUserAgent("my-app/1.0 (monitoring)");

// or disable the default entirely
HttpConfiguration.setUserAgent(null);
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Set it once at startup and every request from your service carries the header you want.

3. Serialization: solon-serialization-fory replaces fury

A new plugin solon-serialization-fory joins the family, and the previous solon-serialization-fury is marked deprecated in favor of it.

If you're on the Fury-based serialization path, switch your dependency:

<dependency>
    <groupId>org.noear</groupId>
    <artifactId>solon-serialization-fory</artifactId>
</dependency>
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4. MultiMap.from() now speaks picocli

MultiMap.from() — the little helper for parsing command-line args into a multi-value map — was optimized in v4.0.5 to be compatible with picocli's parsing strategy. If you build CLI-style entry points (or tools that share arg conventions with picocli-based apps), the parsing behavior now aligns where it previously diverged.

5. Under the hood: smaller packages, cleaner logs

Several internal changes worth knowing about:

  • solon-server-feathttp is now imported from source instead of packaged separately — the release artifact gets smaller.
  • A StatusException fix in solon-handle: AbstractEntityReader.doReadArgument now propagates StatusException correctly (previously it could be swallowed during argument reading). This ties into how Solon maps client-side errors to HTTP status codes like 400/404/405/415 — something I covered in the exception article a few days ago.
  • feat upgraded to 2.3.1: the server header is no longer emitted by default, logging moved to slf4j, and the leftover System.out logging is gone.

6. Dependency refresh

As usual, the release bumps its underlying libraries:

Library Version
eggg 1.1.4
snack4 4.0.59
fastjson 1.2.84
fastjson2 2.0.64
smartsocket 2.1.3
smarthttp 2.5.20

Upgrading

Bump the version in your pom.xml (or build.gradle):

<dependency>
    <groupId>org.noear</groupId>
    <artifactId>solon-parent</artifactId>
    <version>4.0.5</version>
    <type>pom</type>
    <scope>import</scope>
</dependency>
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Full changelog is on GitHub Releases and the official site. If you're running the fury serialization plugin, plan the switch to fory — and if you run WebSocket services behind a proxy, the new ping/pong helpers are a welcome QoL upgrade.

Documentation for this release: https://solon.noear.org — Solon v4.0.5 (Apache 2.0).

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