The is a code sample on how to create a content strategy that sends an email notification when either a content item has been published or has had changes made to it for testing purposes. *Note - This strategy was tested in 9.1 SP1.
PublishSendAlert.cs
This is the class file implementation for the Content Strategy
objectFactory.config
This is the configuration file that has an entry that points to the implementation.
Add the line from from the objectFactory.config to the target site objectfactory.config. This will wire the CMS system with the extensibility code deployment.