Flow Steps (Advanced)

Last Updated: 07/15/2016 Introduced in Verision: 2.0

Summary

While creating simple steps using the Public Static method is easier, you may want to write a full Decisions step if you need to do complex things like have multiple outcome paths or validate input data at design time (e.g. ensure that the value of one input property is set if the value of another property = X).
 
– Why to create
   o Variable inputs or outputs
   o Need advanced configuration
   o Need for custom validation
   o Hiding and showing properties
   o Better user experience when editing
– ISyncStep and IAsyncStep defined
– Creating IAsyncStep
 
Example – Creating ISync Step
In this example we will create a step that evaluates if two numbers divide evenly. This step will result in one of three paths,  Yes, No and  Error .
 
Create a new  Class Library  project is Visual Studio.
 
Add a reference to the  DecisionsFramework dll .
 
Add the following using statements

 Decorate your class with the following attributes

 

Inherit from the following Classes:  BaseFlowAwareStep, ISyncStep, IDataConsumer, IDataProducer  

 
Implement  BaseFlowAwareStep, ISyncStep and IDataConsumer 
 
Your code should now look like this:
 

 

How to build out InputData property
This property defines the input data for the step. Our step need to have two pieces of input data: a divisor and a divisor and a dividend.
 
The InputData property needs to return a DataDescription[] in its get accessor. Each item in the DataDescription[] describes one piece of input data. Here is an example of how to build this array for our step:

 This code above describes two pieces of inputs data. Each are Integers. The words “Dividend” and “Divisor” will be shown in the designer when a user edits the properties of this step.

 
How to build out OutcomeScenarios property
This property defines the outcome data and paths for the step. Our step needs three outcome paths: Yes, No and Error. Only the error path will return data (the error message).
 
The OutcomeScenarios property needs to return a OutcomeScenarioData[] in its get accessor. Each item in the OutcomeScenarioData[] describes one outcome path and the data it returns. Here is an example of how to build this array for our step:

 

How to build out Run method
Since our step has input data, we first want to get that data exposed in the run method. The input data is contained within the StepStartData of the run method and can be accessed as shown in the example below.

Note: the values “Dividend” and “Divisor” must match the values that you entered when building the DataDescription[] within the OutcomeScenarios property.

 
Now that your input data is available within your method you can write whatever code is necessary to accomplish that you want your step to do. The key is that whenever your method ends, you must return a ResultData. Here are two examples, one showing how to build this result data on a path that doesn’t return data and one that does return data:

Note: in the above example the “Error Message” and “Error” must match exactly what was used when writing the OutcomeScenarios property.

 
Hiding Inputs Based on Value of Other Inputs
To hide optional inputs based on the value of a property requires that you inherit from another interface: INotifyPropertyChanged. Implement this interface. Below is a sample of how this interface could be implemented.

When you write a property that you want to use to control other inputs, you can call this method as shown below;

 
Getting your step into Decisions
After you have written your methods build your project, copy the compiled dll to C:\Program Files\Decisions\Decisions Services Manager\modules\Decisions.Local\ServicesDlls, and restart Service Host Manager service.
 
After Service Host Manager has finished restarting, log into the Decisions portal and create a new flow. You will now see the methods from your class in the Toolbox

Additional Resources