Create elements and relationships in UML models


The new home for Visual Studio documentation is Visual Studio 2017 Documentation on

The latest version of this topic can be found at Create elements and relationships in UML models.

In the program code for an extension to Visual Studio, you can create and delete elements and relationships.

Namespace Imports

You must include the following using statements.

The creation methods are defined as extension methods in this namespace:

using Microsoft.VisualStudio.ArchitectureTools.Extensibility.Uml;

Obtain the owner of the element you want to create

A model forms a single tree, so that every item has one owner, except for the model root. The model root is of type IModel, which is a type of IPackage.

If you are creating an element that will be displayed in a particular diagram, for example, the user's current diagram, you should usually create it in the package that is linked to that diagram. For example:

IPackage linkedPackage = Context.CurrentDiagram.Element as IPackage;  

This table summarizes the ownership of common model elements:

Element to be CreatedOwner
IActor, IUseCase, IComponent, IClass, IInterface, IEnumeration

 IActivity, IInteraction
IPackage, IModel
IAttribute, IOperationIClass, IInterface
IPart, IPortIComponent
IAction, IObjectNodeIActivity
ILifeline, IMessage, ICombinedFragmentIInteraction

Invoke the Create method on the owner

The method name is of the form: CreateOwnedType(). For example:

IUseCase usecase1 = linkedPackage.CreateUseCase();  

Some types have more complex creation methods, particularly in Sequence Diagrams. See Edit UML sequence diagrams by using the UML API.

For some types of element, you can change the owner of an element during its lifetime, using SetOwner(newOwner).

Set the name and other properties

usecase1.Name = "user logs in";  


using Microsoft.VisualStudio.Uml.Classes;  
using Microsoft.VisualStudio.Uml.Extensions;  
 void InstantiateObserverPattern (IPackage package, string namePrefix)  
 {    IInterface observer = package.CreateInterface();  
      observer.Name = namePrefix + "Observer";  
      IOperation operation = observer.CreateOperation();  
      operation.Name = "Update";  
      IClass subject = package.CreateClass();  
      subject.Name = namePrefix + "Subject"; ...  

To create an association

  1. Obtain the owner of the association, which is usually the package or model containing the source end of the relationship.

  2. Invoke the required Create method on the owner.

  3. Set the relationship's properties such as its name.

    For example:

    IAssociation association = subject.Package.CreateAssociation(subject, observer);  
    association .Name = "Observes";  
  4. Set the properties of each end of the relationship. There are always two MemberEnds. For example:

    association .MemberEnds[0].Name = "subject";   // role name  
    association .MemberEnds[1].Name = "observers"; // role name  
    association .MemberEnds[1].SetBounds("0..*");           
                // multiplicity defaults to "1"  
    association.MemberEnds[0].Aggregation = AggregationKind.Composite;  
IGeneralization generalization =   


When you delete an element from a model:

  • Every relationship that links to it is also deleted.

  • Every shape that represented it on a diagram is also deleted.

Extend UML models and diagrams
Display a UML model on diagrams