core module consist of next components:
Since A1
    * a4j:ajax
    * a4j:commandButton
    * a4j:commandLink
    * a4j:jsFunction
    * a4j:push
    *  a4j:outputPanel
    * a4j:status
    * a4j:mediaOutput
    * a4j:log
Since A2
    * a4j:poll
    * a4j:param
    * a4j:queue
    * a4j:attachQueue
    * a4j:repeat  
    * a4j:region
