Background Task Manager Template

Overview

The Cloud Application Studio does not allow asynchronous task execution. Webservice calls, Business Object updates.. everything is running in a synchronous way within an application. There is one entity, which runs in background task: Mass Data Run Objects (MDRO). My colleague Stefan Kiefer found a way to leverage MDRO functionality in a normal (non MDRO) application and kick off background tasks via ABSL script. He has built a template, which enables you to quickly leverage this functionality. The template contains an MDRO and the necessary library to schedule and execute background tasks. We call this: The Background Task Manager template.

Technical Implementation

The Background Task Manager is essentially a prebuild set of a fully developed MDRO on top of a custom business object plus libraries that can be used to schedule, execute and check the status of a scheduled task. A normal MDRO can be scheduled on an MDRO screen, which is a manual activity. This template provides libraries that allow you to do this scheduling from an ABSL script. This allows to create background tasks, set parameters and execute code right on any event when ABSL code is run.

The template contains the following entities:

Template Content

• Codelist/BackgroundTaskType.codelist
  The BackgroundTaskType.codelist contains a list of background tasks that can be triggered later on. If you want to use the background task manager to execute 2 independent background tasks, you can add more values here. The key is used to differenciate the tasks in Action-BackgroundTask.absl.
• CustomBOs/BackgroundTaskManager.bo
  This custom business object is used by the MDRO. It hosts all metadata needed to execute the background task.
• CustomBOs/BackgroundTaskManager.bo → MDROQuery.qry
  This the generated MDRO query.
• CustomBOs/BackgroundTaskManager.bo → Root.node → ActionBackgroundTask.absl
  This script contains the code that runs in background.
• CustomBOs/BackgroundTaskManager.bo → Root.node → Event-BeforeSave.absl
  This script handles the transient Parameter3. Only this paramenter can take unlimited text, like a binary string. Per default, this parameter saves the string supplied in an AttachmentFolder.
• CustomBOs/BackgroundTaskManager_*.uicomponent
  These screens can be used in case you want to build a debug environement. Otherwise, these screens can be ignored.
• MDRun/MDR_ExecuteTask.run
  This is the MDRun object. It is configured to operate on the BackgroundTaskManager.bo and takes two arguments: 1) TaskType, which is a value defined in BackgroudTaskType.codelist and 2) TaskUUID, which is a UUID that will identify the created task.
• MDRun/MDR_ExecuteTask_*.uicomponent
  These screens can be used in case you want to build a debug environement. Otherwise, these screens can be ignored.
• ReuseLibrary/MDRO_Lib.library → ExecuteTaskInBackground.absl
  This script can be used to execute a task, which has been scheduled before. It takes a task UUID as argument.
• ReuseLibrary/MDRO_Lib.library → GetTaskStatus.absl
  This script can be used to retrieve the current execution status of a given task. It takes a task UUID as argument.
• ReuseLibrary/MDRO_Lib.library → ScheduleTaskInBackground.absl
  This script can be used to setup and schedule a task in background. It takes a UUID (which you can generate), a task type (from BackgroundTaskType.codelist) and 4 further random parameters. This 4 parameters can be used by you to pass information from the application logic to the background task.

The only entities you need to change when implementing the Background Task Manager are:

• BackgroundTaskType.codelist
• ActionBackgroundTask.absl

Everything else should work out of the box. The template kicks off a task 3 seconds after the “ExecuteTaskInBackground” function is called. In case you want a higher delay, change “PT3S” to a higher value (example PT15S for 15 seconds) in ExecuteTaskInBackground.absl.

Step 1: Import the template into your solution

Open the solution you would like to import the Background Task Manager. Then open the Implementation Manger (View → Implementation Manager). Click Import Template:

Select the template file, which you can download at the end of this blog.

Once the import is finished, you will find the “BackgroundTaskManager” folder in your solution.

Activate all imported entities top down: (Codelist, BO, MDRRun, Libraries)

var TaskUUID : UUID;
TaskUUID.content = Library::UUID.Generate();
MDRO_Lib.ScheduleTaskInBackground(TaskUUID, "001",toRoot.UUID,Context.GetCurrentGlobalDateTime(),toRoot.ID.content.RemoveLeadingZeros(),"");
MDRO_Lib.ExecuteTaskInBackground(TaskUUID);

foreach (var RootInst in this)
{
  var Parameter3String = this.AttachmentFolder.DocumentList.FileContent.GetFirst().BinaryObject.content.ToString();

        switch (RootInst.TaskType)
        {
                case "001"
                {
                        // long running webserive
                }
                case "002"
                {
                        // send a couple of emails
                }
        }
}