View source for AMW/Model Handler

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The [[AMW]] Model Handler enables a better integration of [[ATL]] transformations and weaving models. It provides a set of primitives constantly needed when developing transformations that have weaving models as input or output.

In the [[ATL]] terminology, a model handler is a library providing primitives for handling models, such creating new models, or adding and deleting elements. 

This model handler is an extension to the ATL library of operations. It contributes to the extension point ''org.eclipse.m2m.atl.engine.emfvm.libextension''.

The class ''org.eclipse.gmt.weaver.transformation.operations.UtilOperation'' implements a set of helper methods that can be called when developing ATL transformations that have weaving models as input or as output. The methods can be used for weaving models and for woven models as well. The ''UtilOperation'' class is being improved with new primitives.

==Helper methods methods==

The AMW ''UtilOperation'' class provides methods that can be called on elements of a weaving model or on the elements of the woven models. They are explained below.

===Weaving models===

====getReferredElement====

This method takes as input a ''WLinkEnd'' of a weaving model and it returns the referred element of a woven model (e.g., a MOF!EClassifier). 

Example: 

   rule Example {
      from
          mmw : AMW!ElementEqual ( not '''mmw.left.getReferredElement()'''.oclIsUndefined() )
      to
   ...

===Woven models===

====generateModelRef====

This methods generates the value of the "ref" attribute for a woven model. In other words, it generates an identifier for woven models. The current implementation returns the models' URI.

Example:

   create OUT : AMW from '''left''' : MOF, right : MOF;	
   ...
   rule Example {	
     from 
       ...
     to
        lefta : AMW!ModelRefXMI (
             name <- 'leftModel',
             ref <- '''MOF!EPackage.generateModelRef('left')'''
        )
    }		

====getElementID====

This method returns the identifier (ID) of a woven element. It is necessary to pass as parameter the related weaving model. In that way it is possible to find which ''WElementRef'' is used, and which adapter class is called. The adapter class is the implementation of the identification mechanisms. Ex.: the [http://dev.eclipse.org/viewsvn/viewvc.cgi/plugins/trunk/org.eclipse.gmt.weaver/src/org/eclipse/gmt/weaver/providers/?diff_format=s&root=Modeling_AMW&pathrev=4 providers page] contains example of these adapters, such as the ''XMIIdentifierAdapter'' and the ''GenericIdentifierAdapter''].

Example:

   create OUT : AMW from '''IN''' : AMW, left : MOF, right : MOF;
   ...
   rule example {
      from
         element : MOF!EClass 
      to
         out : AMW!ElementRef (
             name <- element.name,
             ref <- '''element.getElementID('IN')'''
         )
   }

====getElementIDbyRefType====

This method returns the identifier (ID) of a woven element. In this method it is necessary to pass the type of element ref (that inherits from ''WElementRef'') as parameter. The type of ''WElementRef'' specifies which identification mechanism is used. The WElementRefs are associated with adapters of identification mechanisms (see below). For instance, the ''ElementRefXMI'' is associated with the ''XMIIdentifierAdapter'' class. It returns the XMI ID.

This method is used when the user wants to create a new weaving model and he does not have yet the information concerning its identification mechanism.

   rule NewElementRef {
      from
         element : MOF!EClassifier 		
      to
         out : AMW!ElementRefXMI (
            name <- element.name,
            ref <- '''element.getElementIDbyRefType('ElementRefXMI')''',
            modelRef <- element.setModelRef			
         )
   }

====setElementIDbyRefType====

This method sets up the identifier (ID) of a model element. In this method it is necessary to pass the type of element ref (that inherits from ''WElementRef'') as parameter. The type of ''WElementRef'' specifies which identification mechanism is used. The WElementRefs are associated with adapters of identification mechanisms (see below). For instance, the ''ElementRefXMI'' is associated with the ''XMIIdentifierAdapter'' class. It sets up the XMI ID.

The value of the new ID is passed as second parameter. It must be a string object, because it is the same value that should be saved in the ''ref'' attribute of the ''WElementRefs''. If the second parameters is null (OclIsUndefined), the ID will be set up based on the value of the object.

This method is used when the user wants to set up the ID of an element and he does not have yet the information concerning its identification mechanism.

   rule NewElement {
      from
         element : MOF!EClassifier 		
      to
         out : MOF!EClassifier (
         )
      do
        {
         '''out.setElementIDbyRefType('ElementRefXMI', 'newIDValue')''',
      }
   }

==Creating an ATL launch configuration==

The screenshot below shows how to set up an ATL launch configuration with the AMW model handler. The AMW handler will be available in the list of model handlers .

First the user sets up the input and output models . Then the user must select the weaving metamodel (e.g., ''mmw_weaving.core'') or the woven metamodels (e.g., ''MOF''), or both as shown below. Then select 'AMW', and click on the ''Select Model Handler'' button. '''AMW''' is shown in the third column of the ''Path Editor''.

The transformation is ready to run.

[[Image:sample_model_handler.png|center]]


==Download and install==

The UtilOperation class is implemented in the ''org.eclipse.gmt.weaver.transformation'' plug-in. So, this plug-in must be installed. To add user-defined methods, it is necessary to contribute to the ''org.eclipse.m2m.atl.engine.emfvm.libextension'' extension point. Below there is an example of how to declare it.

    <extension
          point="org.eclipse.m2m.atl.engine.emfvm.libextension">
       <libextension
             class="org.eclipse.gmt.weaver.transformation.operations.UtilOperation"
             name="UtilOperation">
       </libextension>
    </extension>

Check the class 
[http://dev.eclipse.org/viewsvn/viewvc.cgi/plugins/trunk/org.eclipse.gmt.weaver.transformation/src/org/eclipse/gmt/weaver/transformation/operations/UtilOperation.java?view=markup&revision=22&root=Modeling_AMW&pathrev=22 org.eclipse.gmt.weaver.transformation.operations.UtilOperation] to understand how to create new helper methods.

[[Category:Modeling]]
[[Category:MDD]]
[[Category:GMT]]
[[Category:AMMA]]
[[Category:AMW]]