asyncworker.html

---
layout: documentation 
title: EvaluationEngine 
teaser: Decouple business logic from control flow
navigation:
   - name: Overview
     link: asyncworker.html 
   - name: Execute asynchronous operation
     link: asyncworkerasyncoperation.html
   - name: Execute code on completion
     link: asyncworkercompletion.html
   - name: Exception Handling
     link: asyncworkerexceptionhandling.html
   - name: Cancel asynchronous operation
     link: asyncworkercancel.html
   - name: Use progress
     link: asyncworkerprogress.html
   - name: Testability
     link: asyncworkertestability.html
---
<h2>Async Worker</h2>
<p>
The Async Worker is used for execution of asynchronous operations. 
It is based on the <code>BackgroundWorker</code> of the .net library but simplifies usage from within code (<code>BackgroundWorker</code> is built to be used within the designer of views).
</p>
<p>
The AsyncWorker provides automatic switching back to the thread where the operation was started.
Please note that this works only if the thread from which the operation was started is associated with a thread synchronizer capable of thread switching. 
This is true for example in the user interface thread.
</p>
<p>
Therefore the AsyncWorker is best used to execute operations from the user interface without blocking it and with the possibility to update the user interface on completion of the operation or to report progress.
</p>
<p>
Finally, the AsyncWorker improves the <code>BackgroundWorker</code> so that when an operation throws an exception then it is not swallowed.
</p>