Transaction Support

The rule engine does not support transactions in general. However, you can update a database in a transactional manner by using the DataConnection object as shown in the following steps:

1. Create a SqlConnection object by using a connection string, and open the connection.

   SqlConnection connection = new SqlConnection("Initial Catalog=Northwind;Data Source=(local);Integrated Security=SSPI;");  
   connection.Open();  
   

2. Create a SqlTransaction object by calling the BeginTransaction method on the connection object you created in step 1.

   SqlTransaction transaction = connection.BeginTransaction();  
   

3. Create a DataConnection object by using the connection and transaction objects you created in steps 1 and 2.

   DataConnection dc = new DataConnection(datasetName, tableName, connection, transaction);  
   

4. Pass the DataConnection object as a fact along with any other facts you want to pass to the policy, and execute the policy.

   //Passing a .NET object as a fact along with the data connection  
   MyClass obj = new MyClass();  
   object[] facts = new object[2];  
   facts[0] = dc;  
   facts[1] = obj;  
   Policy pol = new Policy(policyName);  
   policy.Execute(facts);    
   

5. Invoke the Update method on the data connection object. All the updates done while executing the policy are done only in memory. You must call the Update method on the data connection object to update the database.

   dc.Update();  
   

6. Now, invoke Commit or Rollback on the data connection object based on your own logic.

   //Checking the value of PropertyA in .net object   
   //to decide whether to commit or rollback  
   if (obj.PropertyA == true)  
   transaction.Commit();  
   else  
   transaction.Rollback();  
   
   

7. Close the connection, and dispose the policy object.

   sqlCon.Close();  
   policy.Dispose();  
   

   The following code is the complete code with all the steps:

SqlConnection connection = new SqlConnection("Initial Catalog=Northwind;Data Source=(local);Integrated Security=SSPI;");  
connection.Open();  
SqlTransaction transaction = connection.BeginTransaction();  
DataConnection dc = new DataConnection(datasetName, tableName, connection, transaction);  
MyClass obj = new MyClass();  
object[] facts = new object[2];  
facts[0] = dc;  
facts[1] = obj;  
Policy pol = new Policy(policyName);  
policy.Execute(facts);    
dc.Update();  
if (obj.PropertyA == true)  
transaction.Commit();  
else  
transaction.Rollback();  
sqlCon.Close();  
policy.Dispose();  

Comments

• You can also use the OleDbConnection and OleDbTransaction objects instead of using the SqlConnection and SqlTransaction objects to perform database updates in a transactional manner.

• All the modifications done from the policy are done in memory. You must invoke the Update method on the DataConnection object to update the database.

• You can either commit or roll back the transaction by invoking the Commit or Rollback method of the DataConnection objects respectively.