Spring-Integration AggregatingMessageHandler.setGroupTimeoutExpression visibility

My business logic needs to be able to change configured group timeout on a aggregator.

The code looks like this:

@Autowired
AggregatingMessageHandler messageAggregator;

public void setTimeout(Integer timeoutValue) {
    Expression timeoutExpression = new SpelExpressionParser().parseExpression(timeoutValue.toString());
    messageAggregator.setGroupTimeoutExpression(timeoutExpression);
}

The problem is:

• I want to show the current value to the user, but...
• The getter is protected.

Possible solution scenarios:

• Should I inject an expression on this bean and then change its value,
  • meaning, it will the reevaluate the expression with a new result the next time it builds a message group?
• Should I extend the AggregatingMessageHandler with my own handler that has a public setter?
• Or this is a bug and should be fixed on a next release?

Not sure why you call it as a bug, but your requirement isn't standard.

Let's try to come up with some solution together!

Since you are going to change group-timeout at runtime and you really don't need an expression, bacause your value is just Integer, you can use org.springframework.integration.expression.ValueExpression as a value of the AtomicReference bean.

In this case you can simply show the current value to the user:

@Autowired
private AtomicReference<ValueExpression> groupTimeoutExpression;

....
   this.groupTimeoutExpression.get().getValue();

And use that AtomicReference with a new ValueExpression for the current value and set the last one to the AggregatingMessageHandler.

On the application startup you should do the same for initial group-timeout. Or just copy/paste your value to the group-timeout attribute of the <aggregator> and for the AtomicReference bean.

HTH