Chapter 4 Managing Profiles

Create custom checks on instance links

The robustness analysis implies some behavioral rules between objects. For example, an actor should always communicate with a boundary object (an interface), entity objects should always communicate with control objects, and so on. To represent these constraints, you are going to define custom checks on the instance links.

Custom checks do not prevent users from performing a syntactically erroneous action, but they allow you to define rules that will be verified by the Check Model function.

You define custom checks with VB scripting.

For more information on VBS syntax, see the Scripting User's Guide .

To create custom checks on instance links:

1. Double-click the arrow beside Robustness Extension in the List of Extended Model Definitions to display the resource editor.
2. Right-click the Profile category and select Add Metaclass.
   
   The Metaclass Selection dialog box is displayed.
3. Select InstanceLink in the list of metaclasses displayed in the PdOOM tab and click OK.
   
   The InstanceLink category is displayed under Profile.
4. Right-click the InstanceLink category and select New→Custom Check.
   
   A new check is created.
5. Type Incorrect Actor Collaboration in the Name box.
   
   This check verifies if actors are linked to boundary objects. Linking actors to control or entity objects is not allowed in the robustness analysis.
6. Type "This check ensures that actors only communicate with boundary objects." in the Help Message box.
   
   This text is displayed in the message box that is displayed when the user selects Help in the custom check context menu in the Check Model Parameters dialog box.
7. Type " The following instance links are incorrect:" in the Output Message box.
8. Select Error as default severity.
9. Select the Execute the Check by Default check box.
   
10. Click the Check Script tab.
    
    The Check Script tab is the tab where you type the script for the additional check.
11. Type the following script in the text zone.
    
    

    Function %Check%(link)
       ' Default return is True
       %Check% = True
       ' The object must be an instance link
       If link is Nothing or not link.IsKindOf(PdOOM.cls_InstanceLink) then
          Exit Function
       End If
       ' Retrieve the link extremities
       Dim src, dst
       Set src = link.ObjectA
       Set dst = link.ObjectB
       ' Source is an Actor
       ' Call CompareObjectKind() global function defined in Global Script pane
       If CompareObjectKind(src, PdOOM.Cls_Actor) Then 
          ' Check if destination is an UML Object with "Boundary" Stereotype
          If not CompareStereotype(dst, PdOOM.Cls_UMLObject, "Boundary") Then
             %Check% = False
          End If
    Elsif CompareObjectKind(dst, PdOOM.Cls_Actor) Then 
          ' Check if source is an UML Object with "Boundary" Stereotype
          If not CompareStereotype(src, PdOOM.Cls_UMLObject, "Boundary") Then
             %Check% = False
          End If
       End If
    End Function

12. Click the Global Script tab.
    
    The Global Script tab is the tab where you store functions and static attributes that may be reused among different functions.
13. Type the following script in the text zone.
    
    

    ' This global function check if an object is of given kind
    ' or is a shortcut of an object of given kind
    Function CompareObjectKind(Obj, Kind)
       ' Default return is false
       CompareObjectKind = False
    ' Check object
       If Obj is Nothing Then
          Exit Function
       End If
    ' Shortcut specific case, ask to its target object
       If Obj.IsShortcut() Then
          CompareObjectKind = CompareObjectKind(Obj.TargetObject)
          Exit Function
       End If
    If Obj.IsKindOf(Kind) Then
          ' Correct object kind
          CompareObjectKind = True
       End If
    End Function
    ' This global function check if an object is of given kind 
    ' and compare its stereotype value
    Function CompareStereotype(Obj, Kind, Value)
       ' Default return is false
       CompareStereotype = False
       ' Check object
       If Obj is Nothing or not Obj.HasAttribute("Stereotype") Then
          Exit Function
       End If
    ' Shortcut specific case, ask to its target object
       If Obj.IsShortcut() Then
          CompareStereotype = CompareStereotype(Obj.TargetObject)
          Exit Function
       End If
    If Obj.IsKindOf(Kind) Then
          ' Correct object kind
          If Obj.Stereotype = Value Then
             ' Correct Stereotype value
             CompareStereotype = True
          End If   
       End If
    End Function

14. Click Apply.
    
    You are going to repeat steps 4 to 14 and create one check to verify that an instance link is not defined between two boundary objects:

    Check definition	Content
    Name	Incorrect Boundary to Boundary Link
    Help Message	This check ensures that an instance link is not defined between two boundary objects
    Output Message	The following links between boundary objects are incorrect:
    Default Severity	Error
    Execute the check by default	Selected

15. Type the following check in the Check Script tab:
    
    

    Function %Check%(link)
    
       ' Default return is True
       %Check% = True
    
       ' The object must be an instance link
       If link is Nothing or not 
    link.IsKindOf(PdOOM.cls_InstanceLink) then
          Exit Function
       End If
       
       ' Retrieve the link extremities
       Dim src, dst
       Set src = link.ObjectA
       Set dst = link.ObjectB
       
       ' Error if both extremities are 'Boundary' objects
       If CompareStereotype(src, PdOOM.Cls_UMLObject, "Boundary") Then
          If CompareStereotype(dst, PdOOM.Cls_UMLObject, "Boundary") Then
             %Check% = False
          End If
       End If
       
    End Function

16. Repeat steps 4 to 14 and create one check to verify that entity objects are accessed only from control objects:

    Check definition	Content
    Name	Incorrect Entity Access
    Help Message	This check ensures that entity objects are accessed only from control objects
    Output Message	The following links are incorrect:
    Default Severity	Error
    Execute the check by default	Selected

17. Type the following check in the Check Script tab:
    
    

    Function %Check%(link)
       ' Default return is True
       %Check% = True
       ' The object must be an instance link
       If link is Nothing or not link.IsKindOf(PdOOM.cls_InstanceLink) then
          Exit Function
       End If
       ' Retrieve the link extremities
       Dim src, dst
       Set src = link.ObjectA
       Set dst = link.ObjectB
       ' Source is and UML Object with "Entity" stereotype?
       ' Call CompareStereotype() global function defined in Global Script pane
       If CompareStereotype(src, PdOOM.Cls_UMLObject, "Entity") Then 
          ' Check if destination is an UML Object with "Control" Stereotype
          If not CompareStereotype(dst, PdOOM.Cls_UMLObject, "Control") Then
             %Check% = False
          End If
       Elsif CompareStereotype(dst, PdOOM.Cls_UMLObject, "Entity") Then 
          ' Check if source is an UML Object with "Control" Stereotype
          If not CompareStereotype(src, PdOOM.Cls_UMLObject, "Control") Then
             %Check% = False
          End If
       End If
    End Function

18. Click Apply.
    
19. Click OK in the resource editor.
20. Select Tools→Check Model to display the Check Model Parameters dialog box.
    
    The custom checks appear in the Instance Link category.
    
    
    You can test the checks by creating instance links between Customer and Application server for example, and then press F4 to start the check model feature.
    
    For more information on the Check Model feature, see sections on checking a model in the different user's guides.

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