Any object that wants to exhibit associative behavior, i.e. be automatically evaluated by the associative mechanism when objects it depends on change, needs to be derived from an AssocActionBody class (see comments at the AssocActionBody class) and owned by a parent AssocAction object. The action body is fully owned by its parent action, such as when the parent action is erased, it also erases the owned action body. 

The AssocAction class itself does not have virtual methods that could be overridden, therefore it is not possible for external developers to derive directly from the AssocAction class and override its methods. Internal AutoCAD developers can derive from the AssocAction class and override its virtual methods, but it should only be done when there is no possibility that objects of the derived action classes could become proxies. 

Each action is owned by an AssocNetwork that itself is an action, therefore hirearchical associative structures can be represented. 

The main protocol of the AssocAction class is the evaluate() method that calls the evaluateOverride() method of the owned AssocActionBody object. 

Actions own AssocDependency objects that allow the actions to depend on arbitrary Objects. This is how the connectivity in the network is represented. When objects the dependencies depend on change, the dependencies are notified, actions owning the dependencies are notified and also the hierarchy of the networks owning the actions is notified. This notification just changes AssocStatus of the dependencies and of the actions/networks to "dirty", it does not trigger any action evaluation. 

The actual action evaluation happens when the client code calls the evalaute() method on the top-level network. This automatically evaluates all the actions the network owns that need to be evaluated because they depend, either directly or transitively, on objects that changed. If an action modifies an object (has a write-dependency on it) and there is another action that uses the modified object (has read-dependency on it), then, if the first action is evaluated, the second action also needs to be transitively evaluated. 

The flow of information is as follows: 

Object1 --ReadDep--> Action1 --WriteDep1--> Object2 --ReadDep--> Action2 ... 

Notice that an action may depend on multiple objects and may modify multiple other objects. The network forms a directed acyclic graph. The evalution algoritm makes sure that all actions that need to be evaluated are evaluated and that the evaluation happens in the correct order so that every action is evaluated only after all other actions that modify objects this action depends on have already been evaluated (the situation is actually litle bit more complex, there are other aspects controlling the evaluation order). 

The AssocManager::evaluateTopLevelNetwork() static method should be used to evaluate the top-level network of the database. It will collect and evaluate all the actions that need to be evaluated. Explicit evaluation of the individual sub-networks is not recommended.

Autodesk.AutoCAD.DatabaseServices.DBObject
    Autodesk.AutoCAD.DatabaseServices.AssocAction
        Autodesk.AutoCAD.DatabaseServices.Assoc2dConstraintGroup
        Autodesk.AutoCAD.DatabaseServices.AssocNetwork
        Autodesk.AutoCAD.DatabaseServices.AssocVariable

Public Class AssocAction
Inherits DBObject

public class AssocAction : DBObject;