In the adapter you define a query you want the adapter to execute, which is then executed after a predetermined time period.
i am having a problem that where monitor adapter executes events and how and from where a rule evaluate monitor adapter events
if you have seen the sql monitor adapter config, it contains the query to be executed for the data/records to be monitored and processed in AO along with the interval value at which the query command will get executed.
When you configure the SQL monitor adapter on grid and enable it on Peer, the monitor adapter starts using the config values.
it will execute the query command at regular interval which you configured. and whatever the results comes back will be passed to the rules in modules as events.