Walkthrough: Creating a Ruleflow

This walkthrough presents the following fundamental procedures for creating a ruleflow with ILOG Rule Studio for .NET:

In this walkthrough you create a console application that uses a ruleflow to execute two business rules. The ruleflow also uses a ruleset parameter to keep a count of the number of new account promotions have been made.

Setting up the Business Rule Application

Setting up the application involves creating a solution and defining the classes that model the items of interest in the business domain. You import these classes into the business object model so that you can use them to write rules.

To set up the business rule application

The Message class:

using System;
namespace ClassLibrary1{  
  // Class to print a message
  public class Message
  {
    // Prints a message to the console
    public void PrintMessage(string msg)
    {
      Console.WriteLine(msg);
    }
  }
}
Imports System
' Class to print a message
Public Class Message
    ' Prints a message to the console
    Public Sub PrintMessage(ByVal msg As String)
        Console.WriteLine(msg)
    End Sub
End Class

The Customer class:

using System;
namespace ClassLibrary1{
  //A class for holding customer information
  public class Customer
  {
      //Constructor
    public Customer(int age, bool hasAccount)
    {
      this.age = age;
      this.hasAccount = hasAccount;
    }
 
    // The age of the customer
    private int age;
    public int Age 
    {
      get { return age; }
    }
 
    // Test if the customer has an account.
    private bool hasAccount;
    public bool HasAccount
    {
      get { return hasAccount; }
    }
  }
}
Imports System
' A class for holding customer information
Public Class Customer
    Private m_age As Integer
    Private m_hasAccount As Boolean
 
    'Constructor
    Public Sub New(ByVal age As Integer, ByVal hasAccount As Boolean)
        Me.m_age = age
        Me.m_hasAccount = hasAccount
    End Sub
    'The age of the customer
    Public Readonly Property Age() As Integer
        Get
            Return m_age
        End Get
    End Property
    'Test if the customer has an account
    Public Readonly Property HasAccount() As Boolean
        Get
            Return m_hasAccount
        End Get
    End Property
End Class

Writing the Business Rules

To write the business rules you:

To define the rule project

In this walkthrough the business rules define promotional messages based on the age of a customer. To use a ruleflow you use ruleset parameters to pass the objects of interest to the rule engine. In this case you need two ruleset parameters: one for the customer object, and another for the message. In this walkthrough, there is also a ruleset parameter that keeps a running count of the number of a particular type of promotion that are made as the rules fire.

To define the ruleset parameters

There are two business rules for this walkthrough. The first defines promotional messages for customers older than 16, and the second defines promotional messages for customers younger than 16.

To write the business rules

Creating the Ruleflow

To create the ruleflow you:

To create the ruleflow file

To add a rule task to the ruleflow

To add an action task to the ruleflow

To create a transition from the rule task to the action task

To add the start and end points and the else transition to the ruleflow

The final ruleflow should look something like this:

Defining the Application Logic

To define the application logic you:

To define the application project

To implement the application logic

using System;
using System.IO;
using ILOG.Rules;
using ClassLibrary1;
namespace ConsoleApplication1 
{
  public class RuleExecuter 
  {
    public static void Main() 
    {
      // Create a rule engine in which to execute the ruleset.
      RuleEngine engine = new RuleEngine();
 
      // The promotional message.
      Message promotion = new Message();
 
      // The number of promotions made for new accounts.
      int promo_count = 0;
 
      // The customers to be considered.
      Customer[] customers = new Customer[4];
      customers[0] = new Customer(72, true); //Jack
      customers[1] = new Customer(16, false); //Nandira
      customers[2] = new Customer(45, true); //Laurel
      customers[3] = new Customer(23, false); //Felix
 
      // Load the ruleset into the rule engine.
      engine.RuleSet = new BusinessRules1();
 
      for( int i = 0; i < customers.Length; i++ )
      {
        // set the ruleset parameters
        engine.SetParameterValue("number of promotions", promo_count);
        engine.SetParameterValue("message", promotion);
        engine.SetParameterValue("customer", customers[i]);
 
        // Set the ruleflow to use for executing the ruleset
        engine.Ruleflow = engine.RuleSet.Ruleflows["BusinessRules1", "Ruleflow1"];
 
        // Execute the ruleset.
        engine.Execute();
 
        // Reset the ruleflow before starting again with new ruleset parameters.
        engine.ResetRuleflow();
 
        // Get the value of the running count
        promo_count = (int)engine.GetParameterValues()["number of promotions"];
      }
 
      Console.WriteLine("There were " + promo_count.ToString() + " promotional messages for new accounts.");
 
      //Get the user's input to quit the application.
      Console.WriteLine();
      Console.WriteLine("To exit, press ENTER.");
      Console.In.ReadLine();
    }
  }
}
Imports System
Imports System.IO
Imports ClassLibrary1
Imports ILOG.Rules
Module Module1
 
    Sub Main()
        ' Create a rule engine in which to execute the ruleset.
        Dim engine As New RuleEngine
 
        ' The promotional message
        Dim promotion As New Message
 
        ' The number of promotions made for new accounts
        Dim promo_count As Integer = 0
 
        ' The customers to be considered
        Dim customers As New ArrayList
        customers.Add(New Customer(72, True)) 'Jack
        customers.Add(New Customer(16, False)) 'Nandira
        customers.Add(New Customer(45, True)) 'Laurel
        customers.Add(New Customer(23, False)) 'Felix
 
        ' Load the ruleset into the rule engine.
        engine.RuleSet = New BusinessRules1
 
        ' container for getting the running count
        Dim parameterValues As System.Collections.IDictionary
 
        ' Loop counter
        Dim i As Integer = 0
 
        For i = 0 To customers.Count - 1
            ' Set the ruleset parameters
            engine.SetParameterValue("number of promotions", promo_count)
            engine.SetParameterValue("message", promotion)
            engine.SetParameterValue("customer", customers.Item(i))
 
            ' Set the ruleflow to use for executing the ruleset
            engine.Ruleflow = engine.RuleSet.Ruleflows("BusinessRules1", "Ruleflow1")
 
            ' Execute the ruleset.
            engine.Execute()
            'Reset the ruleflow before starting again with new ruleset parameters.
            engine.ResetRuleflow()
 
            ' Get the value of the running count
            parameterValues = engine.GetParameterValues()
            promo_count = CType(parameterValues("number of promotions"), Integer) Next i
 
        ' Print the number of promotional messages
        Console.WriteLine("There were " + promo_count.ToString() + " promotional messages for new accounts.")
 
        ' Get the user's input to quit the application.
        Console.WriteLine()
        Console.WriteLine("Press ENTER to exit.")
        Console.In.ReadLine()
    End Sub
 
End Module

Running the Business Rule Application

You can test the business rule application within Visual Studio.

To run the business rule application