If a function takes a very long time to complete, Excel is locked and unusable in the meantime. It is sometimes useful to run the function asynchronously, in a separate thread, so that Excel remains available while the function completes. While the calculation is continuing, the target cell will display "#WAIT!", and when it is complete, the result will automatically be updated to display the result.
This chapter shows how to implement an asynchronous model, using the AvgOpt sample as a starting point, and converting it into an asynchronous calculation.
Before you begin using or building the sample code, make sure that your development platform and target environment will support the model: check the requirements in Real-time data requirements.