Status: IN
Observer's notification system requires three independent design decisions: information flow model (push vs. pull, trading observer reusability against protocol efficiency), communication scope (broadcast to unspecified receivers enabling open subscriber sets), and lifecycle safety (subjects must notify observers on deletion to prevent dangling references).
Three previously ungrouped Observer base beliefs form orthogonal notification design axes
Depends on (SL): gof-observer-push-vs-pull-models, gof-observer-supports-broadcast-communication, gof-observer-dangling-reference-on-subject-delete