public string StoreWorkflow(WorkflowObj wfObj)
{
try
{
var wf =
(from w in Workflows
where w.Name == wfObj.Name && w.Version == ConvertVersion(wfObj.Version)
select w).SingleOrDefault();
if (wf == null)
{
wf = new Workflow
{
Name = wfObj.Name,
Version = ConvertVersion(wfObj.Version),
// Description = acObj.Description,
Json = JsonConvert.SerializeObject(wfObj)
};
Workflows.InsertOnSubmit(wf);
}
wf.Json = JsonConvert.SerializeObject(wfObj);
SubmitChanges(ConflictMode.FailOnFirstConflict);
return("\"OK\"");
}
catch (Exception ex)
{
return("\"" + ex.Message + "\"");
}
}
private static void AttemptCleanup(Database db, Execution execution, WorkflowObj workflow, List <History> decisions)
{
if (ExState.Create(execution.ExecutionState.State) == ExState.Cleanup)
{
StopWorkflow(execution, decisions);
return;
}
try
{
var cleanupStartTask = workflow.Tasks.SingleOrDefault(t => t.ActivityName == "cleanup");
if (cleanupStartTask == null)
{
StopWorkflow(execution, decisions);
return;
}
var cleanupTaskId = cleanupStartTask.Outflows.Single(o => o.Name == "Out").Target;
var cleanupTask = workflow.Tasks.Single(t => t.TaskId == cleanupTaskId);
decisions.Add(new WorkflowCleanupStartedEvent());
CreateTaskScheduledEvent(db, execution, cleanupTask, decisions);
}
catch (Exception ex)
{
log.Error("Exception thrown from cleanup", ex);
StopWorkflow(execution, decisions);
}
}
/// <summary>
/// Two stage workflow execution start.
/// First create and initialise the workflow variables
/// Then schedule the first task
/// If this process is interrupted then the variables
/// </summary>
/// <param name="db"></param>
/// <param name="workflow"></param>
/// <param name="execution"></param>
/// <param name="history"></param>
/// <param name="decisions"></param>
private static void ProcessWorkflowExecutionStartedEvent(Database db, WorkflowObj workflow, Execution execution, History history, List <History> decisions)
{
var evt = WorkflowExecutionStartedEvent.Create(history);
CreateVariables(db, evt, execution, workflow);
// Ensure that the variables are set up for the first task
// This should never fail due to conflict
db.SubmitChanges();
// Scheduling the first task
var startTaskId = workflow.Tasks.Single(t => t.ActivityName == "start").Outflows.Single(o => o.Name == "Out").Target;
var startTask = workflow.Tasks.Single(t => t.TaskId == startTaskId);
CreateTaskScheduledEvent(db, execution, startTask, decisions);
}
/// <summary>
/// When a task fails, follow the error outflow if one exists else fail the workflow
/// </summary>
/// <param name="db"></param>
/// <param name="workflow"></param>
/// <param name="execution"></param>
/// <param name="history"></param>
/// <param name="decisions"></param>
private static void ProcessActivityTaskFailedEvent(Database db, WorkflowObj workflow, Execution execution, History history, List <History> decisions)
{
// There should(!) be no contention for the data modified in this process
var evt = ActivityTaskFailedEvent.Create(history);
var se = ActivityTaskScheduledEvent.Create(db.GetHistoryEvent(execution.ExecutionId, evt.SchedulingEventId));
var failedTask = workflow.Tasks.Single(t => t.TaskId == se.TaskId);
var nextTaskId = failedTask.FailOutflow?.Target;
if (!string.IsNullOrEmpty(nextTaskId))
{
var nextTask = workflow.Tasks.Single(t => t.TaskId == nextTaskId);
CreateTaskScheduledEvent(db, execution, nextTask, decisions);
}
decisions.Add(new WorkflowExecutionFailedEvent
{
Reason = $"Task {se.TaskId} failed with no recovery action defined"
});
AttemptCleanup(db, execution, workflow, decisions);
}
/// <summary>
/// Create all workflow variables and initialise them from the workflow input data
/// </summary>
/// <param name="db"></param>
/// <param name="evt"></param>
/// <param name="execution"></param>
/// <param name="workflow"></param>
private static void CreateVariables(Database db, WorkflowExecutionStartedEvent evt, Execution execution, WorkflowObj workflow)
{
foreach (var vdefn in workflow.Variables)
{
// Get the initial value of the variable
JToken value = null;
if (!string.IsNullOrWhiteSpace(vdefn.Value.Path))
{
value = evt.Input.SelectToken(vdefn.Value.Path);
if (value == null) // The path expression failed
{
if (vdefn.Value.Required)
{
throw new ApplicationException("Uninitialised required variable - " + vdefn.Key);
}
}
// Empty default is equivalent to an explicit null
if (IsNullOrUndefined(value) && !string.IsNullOrWhiteSpace(vdefn.Value.Default))
{
value = JToken.Parse(vdefn.Value.Default);
}
}
// Empty literal is equivalent to an explicit null
else if (!string.IsNullOrWhiteSpace(vdefn.Value.Lit))
{
value = JToken.Parse(vdefn.Value.Lit);
}
// TODO: Check datatypes for validity
db.Variables.InsertOnSubmit(new Variable
{
ExecutionId = execution.ExecutionId,
Name = vdefn.Key,
Json = JsonConvert.SerializeObject(value)
});
}
}
/// <summary>
/// Process task completion by scheduling the next task or completing the workflow
/// </summary>
/// <param name="db"></param>
/// <param name="workflow"></param>
/// <param name="execution"></param>
/// <param name="history"></param>
/// <param name="decisions"></param>
private static void ProcessActivityTaskCompletedEvent(Database db, WorkflowObj workflow, Execution execution, History history, List <History> decisions)
{
// There should(!) be no contention for the data modified in this process
var evt = ActivityTaskCompletedEvent.Create(history);
var se = ActivityTaskScheduledEvent.Create(db.GetHistoryEvent(execution.ExecutionId, evt.SchedulingEventId));
var completedTask = workflow.Tasks.Single(t => t.TaskId == se.TaskId);
// Default task outflow
var outflow = "Out";
// Update variables
if (evt.Result != null)
{
// Update the variables if there are any normal results (not prefixed with "$")
if (evt.Result.Properties().Any(p => !p.Name.StartsWith("$")))
{
var variables = db.Variables.Where(v => v.Execution == execution).ToArray();
foreach (var o in completedTask.Outputs.Where(o => o.Value.Var != null))
{
// If the activity has not returned a value for an output then we don't update the mapped variable
// In general it is probably best if activities return values for all outputs to avoid confusion
JToken value;
if (evt.Result.TryGetValue(o.Key, out value))
{
variables.Single(v => v.Name == o.Value.Var).Json = value.ToString(Formatting.None);
}
}
}
// Get the correct outflow
JToken outflowToken;
if (evt.Result.TryGetValue("$outflow", out outflowToken))
{
if (outflowToken.Type == JTokenType.String)
{
outflow = (string)outflowToken;
}
else
{
throw new ApplicationException("Task outflow identifier must be a string");
}
}
}
var nextTaskId = completedTask.Outflows.Single(o => o.Name == outflow).Target;
var nextTask = workflow.Tasks.Single(t => t.TaskId == nextTaskId);
// A task with no outflows is an end
if (nextTask.Outflows.Length == 0)
{
Console.WriteLine($"Execution state = {execution.ExecutionState.State}");
if (ExState.Create(execution.ExecutionState.State) != ExState.Cleanup)
{
CreateWorkflowCompletedEvent(execution, decisions);
}
AttemptCleanup(db, execution, workflow, decisions);
}
else
{
CreateTaskScheduledEvent(db, execution, nextTask, decisions);
}
}
