Additional Windchill Capabilities > Manufacturing Process Management > Transforming an eBOM into an mBOM > Overview of Generate Downstream Structure Action > Delegates Supporting Generate Downstream Structure Action Framework
  
Delegates Supporting Generate Downstream Structure Action Framework
The following delegate classes support the Generate Downstream Structure action framework:
• Preprocessor (BOMGenerationPreProcessDelegate): Out-of-the-box, verifies whether the selected upstream and downstream nodes are equivalent.
• Search (BOMGenerationSearchCriteriaDelegate): Out-of-the-box, matches the upstream and downstream structure using custom attributes.
• Resolver (BOMGenerationResolverDelegate): Out-of-the-box, adds the matching parts in the downstream structure. It restructures the transferred nodes in the downstream structure based on the defined custom attributes.
• Postprocessor (BOMGenerationPostProcessDelegate): Out-of-the-box, creates a log to store the results of the action.
* 
The Propagate Upstream Changes feature calls the search and resolver delegates to ensure that any customized logic is applied when upstream nodes are propagated downstream. So, any logic that is specific to the Generate Downstream Structure action should be added to the preprocessor or postprocessor delegates. For more information on the Propagate Upstream Changes feature, see Propagating Upstream Changes.
* 
When propagating the changes related to added parts, by default, the application considers the equivalent links and common equivalent context that exist between the structures. If you are using the Generate Downstream Structure feature, this default behavior can be changed through the property com.ptc.windchill.associativity.reconciliation.addUsageUsesBomGeneration. The newly added parts in the downstream structure will then follow the logic defined for generating the downstream structure.