/// <summary>
/// Execute the workflow from the beginning.
/// </summary>
public WorkflowState Execute(T data)
{
WorkflowContinuation <T> continuation = new WorkflowContinuation <T>(this);
WorkflowState state = InternalContinue(continuation, data);
return(state);
}
/// <summary>
/// Internally, we execute workflow steps until:
/// 1. we reach the end of the workflow chain
/// 2. we are instructed to abort the workflow
/// 3. we are instructed to defer execution until later.
/// </summary>
protected WorkflowState InternalContinue(WorkflowContinuation <T> wc, T data)
{
WorkflowState state = WorkflowState.Done;
while ((wc.WorkflowStep < items.Count) && !wc.Abort && !wc.Defer && !wc.Done)
{
try
{
state = items[wc.WorkflowStep++].Execute(wc, data);
switch (state)
{
case WorkflowState.Abort:
wc.Abort = true;
wc.Workflow.AbortHandler(data);
break;
case WorkflowState.Defer:
wc.Defer = true;
break;
case WorkflowState.Done:
wc.Done = true;
break;
}
}
catch (Exception ex)
{
// Yes, the user's exception handler could itself through an exception
// from which we need to protect ourselves.
try
{
wc.Workflow.ExceptionHandler(data, ex);
}
catch { /* Now what? */ }
// TODO: Should we use a different flag, like "Exception"? Can't be Abort, as this invokes an app-specific handler.
state = WorkflowState.Exception;
wc.Done = true;
}
}
if (wc.Defer)
{
// Synchronization, we're done with this loop and the workflow can now continue on another thread.
wc.Deferred = true;
}
// If the loop exits and the last workflow state was continue, then we're actually now done.
if (state == WorkflowState.Continue)
{
state = WorkflowState.Done;
}
return(state);
}
/// <summary>
/// Continue a deferred workflow, unless it is aborted.
/// </summary>
public WorkflowState Continue(WorkflowContinuation <T> wc, T data)
{
WorkflowState state = WorkflowState.Undefined;
// TODO: Throw exception instead?
if ((!wc.Abort) && (!wc.Done))
{
wc.Defer = false;
wc.Deferred = false;
state = InternalContinue(wc, data);
}
return(state);
}
/// <summary>
/// Execute the workflow item method.
/// </summary>
public WorkflowState Execute(WorkflowContinuation <T> workflowContinuation, T data)
{
return(doWork(workflowContinuation, data));
}
