gnodet opened a new pull request, #27956:
URL: https://github.com/apache/camel/pull/27956
## Summary
Fix OPC-UA write/call/readValues/browse service failures being silently
swallowed and reported as success when using the awaited
(`CamelMiloAwait=true`) mode.
## Root Cause
`SubscriptionManager.write()`, `call()`, `readValues()`, and `browse()` all
chained the underlying Milo client future with `handleAsync()`:
```java
return this.connected.write(nodeId, value).handleAsync((status, e) -> {
if (e != null) {
handleConnectionFailure(e);
}
return status; // returns null when e != null
}, this.executor);
```
When the OPC-UA operation fails (e.g. `Bad_Timeout` service fault),
`handleAsync` receives a non-null exception. It calls
`handleConnectionFailure(e)` for the reconnection side-effect, then **returns
the value (null)**, converting the exceptional completion into a normal null
completion.
`MiloClientProducer` awaits the returned future and only propagates errors
when the throwable is non-null:
```java
future.whenComplete((result, throwable) -> {
if (throwable != null) exchange.setException(throwable);
else msg.setBody(result); // sets null body → reports success
});
```
Since `handleAsync` had already discarded the exception, the producer saw a
null-completed future, set the body to `null`, and reported success. No error
was raised to the Camel route.
## Fix
Replace `handleAsync()` with `whenCompleteAsync()` in all four methods.
`whenCompleteAsync` runs the side-effect (reconnection) but propagates the
original completion unchanged — exceptions stay exceptional, successes stay
successful:
```java
return this.connected.write(nodeId, value).whenCompleteAsync((status, e) -> {
// handle outside the lock, running using
// whenCompleteAsync (preserves the original exceptional completion)
if (e != null) {
handleConnectionFailure(e);
}
}, this.executor);
```
## Tests
Two new test classes:
- **`MiloClientProducerWriteFailureTest`**: tests that `MiloClientProducer`
correctly propagates awaited write/call failures as exchange exceptions, and
that non-awaited (fire-and-forget) writes do not set exceptions. Uses a
`MiloClientConnection` stub returning pre-arranged futures.
- **`SubscriptionManagerExceptionPropagationTest`**: tests the
`whenCompleteAsync`-vs-`handleAsync` future completion contract directly (no
server needed), and verifies that disconnected managers return exceptional
futures from `write()`, `call()`, and `readValues()`.
Fixes https://issues.apache.org/jira/browse/CAMEL-25694
_Hermes Agent (Claude Sonnet 4.6) on behalf of Guillaume Nodet_
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