Extracting Constraint from Requirement

The Extracting Constraint from Requirement functionality gives an ability to verify Requirements easier when trying to prove the assertion is true (or false). A glossary mechanism extracts constraint directly from Requirement text. If you want to create constraints and associate them with requirements automatically, you can use the extract Constraint from Requirement text functionality. For this, firstly you need the following conditions would be implemented in your model:

• The Use Requirement Term Glossary option is enabled.
• Requirement texts contain such format: condition term+number, e.g. at least 70.
• Custom condition terms are defined in the <<requirementTerms>> Glossary table.
• The satisfy relationship is created between design element and requirement.
  

To extract Constraint value from Requirement text

1. Make sure the Use Requirement Term Glossary option is enabled.
2. Define Requirement text with condition term and number.
3. Create the satisfy relationship between the specific value of design element and requirement.
   
4. Extract Constraint from Requirement text.
   

Enabling/disabling Requirement term glossary usage option

If your project is created using an older modeling tool version than 18.4, the Use Requirement Term Glossary option is disabled by default.

To enable/disable Requirement term glossary usage

1. From the main menu, click Options > Environment.
2. In the Environment Option dialog, find the Use Requirement Term Glossary option.
3. Set its value to true to enable the Requirement term glossary usage in the model, or false - to disable it.

Defining Requirement with condition terms

Extract Constraint from Requirement functionality requires the specific definition of Requirement texts. The statement in the text property of the Requirement, typed in the string format, must contain condition term+number (e.g. at least 70). Note, that the Unit symbol is not supported. You have two options when trying to use condition terms:

• Use from predefined requirement terms glossary table.
• Define your own condition phrases by creating a new glossary table stereotyped by <<requirementTerms>>.

To open glossary table with frequently used condition terms

   a. In the Model Browser, click  and select Show Auxiliary Resources button.
   b. Expand MD Customization for Requirements Package > requirement terms Package.
   c. Double-click the Glossary to open the table (see figure below).

The glossary table opens where are stored frequently used condition terms (see the following figure).

To create a new glossary table with the stereotype <<requirementTerms>>

1. From the main toolbar, click the Create Diagram button.
2. Double-click the glossary table icon.
3. Open the Specification window of newly created Glossary table.
4. Change the Applied Stereotype property value to <<requirementTerms>>.
5. Click Close.
   The new glossary table with the stereotype <<requirementTerms>> is created. You are able to define your own condition terms by adding them in the Glossary Table.

Creating the satisfy relationship

The specific value of the design element need to satisfy the Requirement. As displayed in this example below, the distanceOnQuickCharge value of the Hight-voltage Battery Block satisfies the Quick change mode distance Requirement.

Extracting Constraint from Requirement

To extract Constraint from Requirement

1. Right-click a value property in the compartment area of the design element shape.
2. Select Tools > Extract Constraint From Requirement.
   The constraint is created automatically with a value and condition term which were defined in the Requirement.

Look at the example below, the text "at least 1500" of the Quick change mode distance Requirement is automatically parsed to "distanceOnQuickCharge >= 70" and solved as constraint.

After selecting the Extract Constraint From Requirement command, the constraint {distanceOnQuickCharge >=70.0} is automatically created and it satisfies the requirement text "at least 70".