Mechanical Modeler

What is an Extension Feature?

An Extension Feature is a specific feature which allows you to add behaviors or data (like parameters) on a "Base Feature" without modifying its structure. You can create the Startup using the OSM technology [5], or using the CATIOsmExtensionFactory interface in the code creating the feature's catalog.

Conversely to a traditional Startup, creating a Extension's StartUp is not enough, you should provide a CATNls file too. This additional resource's file determines its "extendibility" and its applicative container in which it will be instantiated. It is fully explained in the referenced article [1].

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Extension Features in Mechanical Modeler context - Restrictions

Globally, Extension Features, defined by Feature Modeler, could extend a multitude of features.

However, in Mechanical Modeler, we recommend you to restrict your extension to the features defined below:

• Mechanical Part
• Mechanical Tool
• GSMTool
• User Features
• GeometricalElement3D

Of course, all their subtypes and derivatives support also Extension Features.

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Adding data and behaviors

As said before, Extensions are specific features which allow you to add behaviors and parameters on base features. It means that once the new feature is created, you can provide him behaviors by implementing interfaces.

The Extension feature that you will define, will derive from a specific Feature Modeler's feature. So it means that your feature will take benefit from interfaces natively implemented on the derived DS feature (The CATINavigateObject interface is an example). But take care, the derived DS feature is not the base feature which is extended, it is the StartUp whose derives your feature)
 

Here are listed the main behavior to take into account, but for a complete application, this list can be extended.

• LifeCycleObject

There is an implementation of this interface on the DS feature whose derives your extension feature. But this implementation is not specific to a feature extension, so you can re-implement it to use RemoveExtension method of CATIOsmExtendable interface.

• Add Data - Parameters
  Extension Features are useful to add parameters or attributes to a base feature even if you don't have any rights on it.
  
  How does it work?
  Well, this addition is not really done on the base feature itself, but, the Extension Feature held the parameters and data you want to add to your base feature. Extending the base feature, you add indirectly those attributes!
   
• Useful interfaces to implement
  Just like traditional features, it might be useful to implement some interfaces on Extension Features to obtain specified behaviors.
  
   
  • Customize the f(x) - CATIParmPublisher interface
    To manage Extension's parameters, it will be useful to implement CATIParmPublisher. This Interface declares which parameters user can see and interact with in f(x).
    
     

    Implementation of CATIParmPublisher on CAADataExtension.

  • Customize Spec Tree: CATINavigateObject - CATINavigateFilter
    To show Feature Extension  and its aggregated parameters in the Graph, you can implement "CATINavigateObject" interface. However, it is not mandatory to implement it since the feature whose your extension's feature derives already implement it.

    In order to show or not your feature extension in the spec tree, you must implement the CATINavigateFilter interface on the Feature Extension. The extended feature will be visible just beneath the extended feature such as depicted by the above picture (blue node on left).
    
     

    User View with CATINavigateFilter::IsShown returning TRUE	User View with CATINavigateFilter::IsShown returning FALSE

    
    Please, note that if you do not implement the CATINavigateFilter interface, the behavior is not guarantee: the extended feature can be visible, like it can be hidden.
     

  • Customise Build - Compute Extension
    
    If extensions have to compute something, it will be necessary to implement CATIBuild on them, like it is done on traditional features.
    Please, note that if you do this, you will have to set a "Provider Mechanism" between the applicative container, containing the Extension, and the CATPrtCont because of default update mechanism.[6]

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Extension Feature integration in Mechanical Modeler - Provider Mechanisms on MechanicalPart

As Extensions are instantiated into applicative container, it may be useful to implement providers to extend behaviors normally restricted to CATPrtCont (like Update Mechanism) on this applicative container.

Please refer to article “Working with Providers in Mechanical Part” [6] for more information about this specified mechanism.

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In Short

Extensions are specific features dedicated to add behaviors and customize existing features. They must be defined in a catalog, declared in a resource file and they must implement interfaces to customize the behaviors wanted.

In some cases, it is useful to set up Providers between CATPrtCont and applicative container in order to extend behaviors like Update mechanism...Which is commented in another article [6] .

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References

History

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