Getting 'This operation is forbidden on unbound objects' when trying to monitor an Azure Batch task

Question

I want to execute a simple task in Azure Batch, to wait until it completes and to get the result:

using (var client = _CreateBatchClient())
{
    var monitor = client.Utilities.CreateTaskStateMonitor();

    var task = new CloudTask(Guid.NewGuid().ToString(), "echo hello world");
    await client.JobOperations.AddTaskAsync("Test", task);
    await monitor.WhenAll(new List<CloudTask> { task }, TaskState.Completed, _timeout);

    var result = task.ExecutionInformation.Result;
}

And the WhenAsync line throws System.InvalidOperationException: 'This operation is forbidden on unbound objects.'

The message is quite obscure whereas I am not far from the tutorial. What is wrong?

score 4 · Accepted Answer · answered Jun 11 '19 at 12:58

It is not obvious from this code yet actually Azure Batch does not know here how to identify the task. The job contains tasks but a task has no reference to a job it runs on. And the task Id does not globally identify the task as well, it only needs to be unique within a job.

This is probably the meaning of "unbound objects" here. The monitor just does not understand what to watch. Actually, if the WhenAsync line is commented, the next one throws a similar InvalidOperationException: 'The property ExecutionInformation cannot be read while the object is in the Unbound state.'

So the right way is to reference the task via the job:

using (var client = _CreateBatchClient())
{
    var monitor = client.Utilities.CreateTaskStateMonitor();

    var id = Guid.NewGuid().ToString();
    var taskToAdd = new CloudTask(id, "echo hello world");
    await client.JobOperations.AddTaskAsync("Test", taskToAdd);

    var taskToTrack = await client.JobOperations.GetTaskAsync("Test", id);
    await monitor.WhenAll(new List<CloudTask> { taskToTrack }, TaskState.Completed, _timeout);
}

Compare:

And to get the result information, one needs to "find" the task in the job again, or it will be null.

Getting 'This operation is forbidden on unbound objects' when trying to monitor an Azure Batch task

1 Answers1