Some preliminary remarks on the implementation of this feature:

• there is already a mechanism which handles specific exceptions occurring during node I/O. For instance when a NotSerializableException is thrown when serializing/serializing a job on the node side. This feature is something different and requires a separate mechanism.
• the server will have to be able to keep track of multiple exceptions occurring on multiple task bundles dispatched to one or more nodes. This implies something similar to a data provider with read/write capability instead of read-only
• this raises the question of whether we should generalize this mechanism so that it can be used for more than just error reporting.
• this will also require a public API for JPPFJob to handle this.
• we should also think of the possibilities this may open up. For instance, we could consider some server plugins/extensions point that could use the returned data and alter the handling of the job on the server side.

As the 4.0 release is already late, I am pushing back this feature to 4.1 milestone.

In the meantime, a possible approach to accomplishing with user-defined code:

1. define an interface ErrorHolder:

public interface ErrorHolder {
  void setErrorInfo(Object object);
}

2. have the tasks implement this interface so they can hold a reference to the error information

3. In the NodeLifeCycle implementation, capture any error that occurs in the implemented methods

4. In the jobEnded() method iterate over the completed tasks until one is found which implements ErrorHolder. If one is found, call setErrorInfo() and then clear the error from the NodeLifeCycle.