To debug a piece of .NET code called by the BRE you must first attach the Visual Studio debugger to the BRE process.   To accomplish this, open the debug menu and select “attach to process…” and select the Microsoft.RuleComposer process.  Now you can put breakpoints on the desired lines of .NET code and when the rule executes from the BRE, the execution will catch at the first breakpoint.

Facts can be asserted to the BRE from .NET code simply by passing them as an argument to the policy’s execute method which takes a variable number of parameters.  For example,

Microsoft.RuleEngine.Policy policy = new Microsoft.RuleEngine.Policy(“PolicyName”);
Policy.Execute(Object1, Object2,…);

There are three types of facts used by the BRE:  An xml document, a Database table, and a .NET class.  The latter two have a couple peculiarities about them which require further explanation. 

Asserting a Database Table

When using a database table, the BRE expects an object of type Microsoft.RuleEngine.DataConnection to be asserted, which tells the BRE where to find the table.  This is achieved with the below code.

//Create the DataConnection
System.Data.SqlClient.SqlConnection connection = new System.Data.SqlClient.SqlConnection(“connectionstring”);
Microsoft.RuleEngine.DataConnection dconn = new Microsoft.RuleEngine.DataConnection(connection);

//Create the policy and assert the DataConnection
Microsoft.RuleEngine.Policy policy = new Microsoft.RuleEngine.Policy(“PolicyName”);
Policy.Execute(dconn);

Static .NET Methods

Calling a static .NET method from the BRE can be achieved without asserting an instance of the class by setting the the StaticSupport (DWORD value) registry key located under HKEY_LOCAL_MACHINE\Software\Microsoft\BusinessRules\3.0 to a value of 1.  Without this registry entry, static method calls within the BRE will require asserting instances of the class that contain the method.

Even though the Business Rules Engine (BRE) is included with BizTalk 2006, it does not need to be exclusively called by the BizTalk host.  The BRE has a .NET API library that enables any host to communicate with the engine programmatically.
You must first reference the Microsoft.BizTalk.RuleEngineExtensions.dll from the BizTalk installation directory (the default installation is C:\Program Files\Microsoft BizTalk Server 2006).

You can then call BRE policies with the following code

Microsoft.RuleEngine.Policy policy = new Microsoft.RuleEngine.Policy(“PolicyName”);
Policy.Execute();

The execute method can take any number of objects as a parameter that need to be asserted as facts to the BRE for execution.