The action currently being carried out. Most operations consist of multiple actions.
A list of errors that occurred in the most recent action of the child process.
An exception that occured in the most recent action of the child process. This is usually null, since most errors are expected and handled, and will show up in the errors array.
When this is not null, it usually means an unexpected error occurred which prevented the operation from completing.
A message describing what is happening in the child process.
The name of the operation that the child process is currently carrying out. See Constants.OP_STATUSES for a list of valid values.
Percent completion of the task. This should be a number between 0 and 100. If it's less than zero, it should be ignored.
The status of the child process. See Constants.OP_STATUSES.