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Walkthrough: Testing the Policy

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This walkthrough provides step-by-step procedures for testing the policy you created in the Walkthrough: Creating a Simple Business Policy walkthrough.

Prerequisites

You must complete the Walkthrough: Creating a Simple Business Policy walkthrough before you perform this walkthrough.

Overview of This Walkthrough

This walkthrough contains two procedures, as described in the following table.

Procedure title Procedure description
To create the test files Provides step-by-step instructions for creating two sample XML files, one with the value of the Quantity field as 400 (<= 500) and the other one with the value of the Quantity field as 700 (> 500).
To test the ProcessPurchaseOrder policy Provides step-by-step instructions for testing the policy using Business Rule Composer.

To create the test files

  1. On the Start menu, open Notepad.

  2. Copy the following XML to Notepad:

    <ns0:PurchaseOrder xmlns:ns0="http://EAISolution.PurchaseOrder">  
  <Header>  
    <ReqID>ReqID_0</ReqID>  
    <Date>Date_0</Date>  
  </Header>  
  <Item>  
    <Description>Description_0</Description>  
    <Quantity>400</Quantity>  
    <UnitPrice>20</UnitPrice>  
  </Item>  
  <Status>XYZ</Status>  
</ns0:PurchaseOrder>

  3. On the File menu, click Save TextFile1.txt As.

  4. Change the value for Save As type from Text Documents(*.txt) to All Files.

  5. Change the directory to C:\BRE-Walkthroughs.

  6. Type SamplePO.xml for File name, and then click Save.

  7. On the File menu, click New.

  8. Copy the following XML to Notepad:

    <ns0:PurchaseOrder xmlns:ns0="http://EAISolution.PurchaseOrder">  
  <Header>  
    <ReqID>ReqID_0</ReqID>  
    <Date>Date_0</Date>  
  </Header>  
  <Item>  
    <Description>Description_0</Description>  
    <Quantity>700</Quantity>  
    <UnitPrice>20</UnitPrice>  
  </Item>  
  <Status>XYZ</Status>  
</ns0:PurchaseOrder>

  9. On the File menu, click Save TextFile1.txt As.

  10. Change the value for Save As type from Text Documents(*.txt) to All Files.

  11. Change the directory to C:\BRE-Walkthroughs.

  12. Type SamplePO2.xml for File name, and then click Save.

  13. Close Notepad.

To test the ProcessPurchaseOrder policy

  1. On the Start menu, open Business Rule Composer. If you have Business Rule Composer already open, press F5 to refresh it.

    Note

    On a system that supports User Account Control (UAC), you may need to run the tool with Administrative privileges. To do this, right-click the application, and then select Run as administrator.

  2. In the Policy Explorer window, expand Policies, expand ProcessPurchaseOrder, right-click Version 1.0, and then click Test Policy.

  3. In the XMLDocuments node, select RuleTest.PO, and then click Add Instance.

    Business Rule Composer-TestPolicySelectFacts

  4. Select the SamplePO.xml file that you created earlier, and then click Open.

  5. Click Test.

  6. Review the output in the Output window. See the "Analysis of the Output from the First Test (samplepo.xml)" section for an explanation of the output you see.

  7. Open SamplePO.xml in Notepad and notice that the value of the Status field is set to Approved.

  8. Right-click Version 1.0, and then click Test Policy.

  9. Select SamplePO.xml, click Remove instance, and then click Add Instance.

  10. Select the SamplePO2.xml file that you created earlier, and then click Open.

  11. Click Test. See the "Analysis of the Output from the Second Test (samplepo2.xml)" section for an explanation of the output you see.

  12. Open the SamplePO2.xml file in Notepad and notice that the value of the Status field is still XYZ.

Analysis of the Output from the First Test (samplepo.xml)

Note

The output text is bold and the explanation follows the output text.

RULE ENGINE TRACE for RULESET: ProcessPurchaseOrder 8/31/2006 1:33:10 PM

The rule engine trace for the execution of policy ProcessPurchaseOrder started at 8/31/2006 1:33:10 PM.

FACT ACTIVITY 8/31/2006 1:33:10 PM

Rule Engine Instance Identifier: bc4f1cf5-e9a2-49d0-9cdd-76a2ac057240

Ruleset Name: ProcessPurchaseOrder

Operation: Assert

Object Type: TypedXmlDocument:PurchaseOrder

Object Instance Identifier: 14626574

When you click Test, the following things happen:

  1. The Business Rule Composer creates a RuleEngine.Policy object, which in turn creates a new rule engine instance or acquires a rule engine instance from the rule engine cache.

  2. The Business Rule Composer creates a TypedXmlDocument object based on the SamplePO.xml file.

  3. The Business Rule Composer invokes the Policy.Execute method with the TypedXmlDocument object as a parameter.

  4. The Policy.Execute method asserts (adds) the TypedXmlDocument object as a fact into the working memory of the rule engine.

  5. The rule engine uses the TypedXmlDocument object as a fact and executes the ProcessPurchaseOrder policy.

    FACT ACTIVITY 8/31/2006 1:33:10 PM

    Rule Engine Instance Identifier: bc4f1cf5-e9a2-49d0-9cdd-76a2ac057240

    Ruleset Name: ProcessPurchaseOrder

    Operation: Assert

    Object Type: TypedXmlDocument:PurchaseOrder:/PurchaseOrder

    Object Instance Identifier: 64530307

    FACT ACTIVITY 8/31/2006 1:33:10 PM

    Rule Engine Instance Identifier: bc4f1cf5-e9a2-49d0-9cdd-76a2ac057240

    Ruleset Name: ProcessPurchaseOrder

    Operation: Assert

    Object Type: TypedXmlDocument:PurchaseOrder:/PurchaseOrder/Item

    Object Instance Identifier: 43901854

  6. The rule engine determines which child TypedXmlDocument objects to create based on the XPath selectors defined in the rules. When you build rules in the Business Rule Composer, the XPath selector value defaults to the node above the node selected in the XML Schemas tab in Facts Explorer. The XPath field value defaults to the selected node itself, relative to its parent node. However, if the node you selected has children, only an XPath selector binding is created to point to the node that you selected, and no XPath field binding is created.

  7. The following table shows the XPath Selector and XPath Field binding values for the fields used in the ProcessPurchaseOrder policy. (The policy has only one rule, ApprovalRule.)

Field name XPath Selector XPath Field XPath Selector (simplified form) XPath Field

(simplified form)
Quantity /*[local-name()='PurchaseOrder' and namespace-uri()='http://EAISolution.PurchaseOrder']/*[local-name()='Item' and namespace-uri()=''] *[local-name()='Quantity' and namespace-uri()=''] /PurchaseOrder/Item Quantity
Status /*[local-name()='PurchaseOrder' and namespace-uri()='http://EAISolution.PurchaseOrder'] *[local-name()='Status' and namespace-uri()=''] /PurchaseOrder Status

To view the Xpath Selector and Xpath Field bindings for the Quantity and Status fields

  1. In the Policy Explorer window, expand Policies, expand ProcessPurchaseOrder, and then expand Version 1.0.

  2. Click ApprovalRule.

  3. In the IF pane on the right, click PO:/PurchaseOrder/Item/Quantity.

  4. Verify that you see the value shown in the preceding table for the XPath Selector and XPath Field bindings in the Properties window.

  5. Repeat steps 3 and 4 for the PO:/PurchaseOrder/Status field.

    The rule engine creates a child TypedXmlDocument object from the original TypedXmlDocument you submitted for each XPath selector. Because there are two distinct XPath selectors used in the policy (/PurchaseOrder/Item for the Quantity field and /PurchaseOrder for the Status field), the rule engine creates two child TypedXmlDocument objects and asserts them into the working memory of the rule engine.

Note

To see the trace output again, click Version 1.0 in the Policy Explorer window.

CONDITION EVALUATION TEST (MATCH) 8/31/2006 1:33:10 PM

Rule Engine Instance Identifier: bc4f1cf5-e9a2-49d0-9cdd-76a2ac057240

Ruleset Name: ProcessPurchaseOrder

Test Expression: TypedXmlDocument:PurchaseOrder:/PurchaseOrder/Item.Quantity <= 500

Left Operand Value: 400

Right Operand Value: 500

Test Result: True

AGENDA UPDATE 8/31/2006 1:33:10 PM

Rule Engine Instance Identifier: bc4f1cf5-e9a2-49d0-9cdd-76a2ac057240

Ruleset Name: ProcessPurchaseOrder

Operation: Add

Rule Name: ApprovalRule

Conflict Resolution Criteria: 0

The rule engine uses the three-stage Condition Evaluation-Conflict Resolution-Action Execution algorithm to execute policies. In the Condition Evaluation stage, the rule engine evaluates the conditions in all the rules in the policy and adds the rules whose conditions evaluate to true to the agenda. In this simple example, the ProcessPurchaseOrder policy has only one rule, ApprovalRule. Therefore, the rule engine evaluates the condition, Quantity <= 500, in the ApprovalRule using the value of the Quantity field in the submitted XML document, which is 400. The output above shows you the values of the left operand, right operand, and test result.

In the second stage, the Conflict Resolution Criteria stage, the rules whose conditions evaluate to true are added to the agenda in order based on their priority. In this scenario, the rule engine adds the ApprovalRule to the agenda because the condition for the ApprovalRule evaluated to true. The Conflict Resolution Criteria shown in the output above is only the priority on the rule (ApprovalRule). If you click the ApprovalRule node in the Policy Explorer window, you can see the value of the Priority property on the rule in the Properties window as 0, which is the default value of a rule. If you have multiple rules in a policy, and you want to make sure that actions in one rule are executed after actions in another rule, you should set the priority appropriately. The larger the number, the higher the priority.

RULE FIRED 8/31/2006 1:33:10 PM

Rule Engine Instance Identifier: bc4f1cf5-e9a2-49d0-9cdd-76a2ac057240

Ruleset Name: ProcessPurchaseOrder

Rule Name: ApprovalRule

Conflict Resolution Criteria: 0

In the last stage, the Action Execution stage, the rule engine starts executing the actions in the rule. There is one action in the ApprovalRule, which sets the value of the Status field in the submitted XML document to Approved.

FACT ACTIVITY 8/31/2006 1:33:10 PM

Rule Engine Instance Identifier: bc4f1cf5-e9a2-49d0-9cdd-76a2ac057240

Ruleset Name: ProcessPurchaseOrder

Operation: Retract

Object Type: TypedXmlDocument:PurchaseOrder

Object Instance Identifier: 14626574

FACT ACTIVITY 8/31/2006 1:33:10 PM

Rule Engine Instance Identifier: bc4f1cf5-e9a2-49d0-9cdd-76a2ac057240

Ruleset Name: ProcessPurchaseOrder

Operation: Retract

Object Type: TypedXmlDocument:PurchaseOrder:/PurchaseOrder/Item

Object Instance Identifier: 43901854

FACT ACTIVITY 8/31/2006 1:33:10 PM

Rule Engine Instance Identifier: bc4f1cf5-e9a2-49d0-9cdd-76a2ac057240

Ruleset Name: ProcessPurchaseOrder

Operation: Retract

Object Type: TypedXmlDocument:PurchaseOrder:/PurchaseOrder

Object Instance Identifier: 64530307

All the facts submitted (PurchaseOrder) to the rule engine and the child facts created by the rule engine based on XPath selectors (\PurchaseOrder and \PurchaseOrder\Item) are retracted (removed) from the working memory of the rule engine.

Analysis of the Output from the Second Test (samplepo2.xml)

CONDITION EVALUATION TEST (MATCH) 9/5/2006 5:24:42 PM

Rule Engine Instance Identifier: b749d2fd-a883-4c2f-9974-5cf688010622

Ruleset Name: ProcessPurchaseOrder

Test Expression: TypedXmlDocument:PurchaseOrder:/PurchaseOrder/Item.Quantity <= 500

Left Operand Value: 700

Right Operand Value: 500

Test Result: False

The rule engine evaluates the condition (Quantity <= 500) in the ApprovalRule using the lone Item object. You can see that left operand value is the value of the Quantity element in the XML document, 700. The test result is false because 700 <= 500, so the rule is not added to the agenda of the rule engine. There is no rule in the agenda. Therefore, there are no actions to execute, and the value of the Status field remains XYZ.

Comments

  • We recommend that you test the policies before using them from client applications such as BizTalk applications.

  • When you test a policy that uses database facts with the DataConnection binding in the Business Rule Composer, a DataConnection object is automatically built for you. However, when you call the same policy from an orchestration by using the Call Rules shape, no DataConnection object is passed to the policy automatically. You should create a DataConnection object in the orchestration and pass it as a parameter or create a fact retriever component that asserts the DataConnection object, and configure the policy to use the fact retriever component.

  • To test a policy that uses a .NET fact, you should create a fact creator component and specify it in the Select Facts dialog box. For more information about creating fact creators, see How to Create a Fact Retriever. You can do the same thing when the policy uses database facts (TypedDataConnection or TypedDataTable or TypedDataRow) or XML facts (TypedXmlDocument).

Next Steps

Now that you have completed this walkthrough, perform the Walkthrough: Invoking the Policy from an Orchestration walkthrough, which gives you step-by-step instructions for invoking the ProcessPurchaseOrder policy from an orchestration.

See Also

Policy Test Trace Output
Condition Evaluation and Action Execution
Agenda and Priority