I have no knowledge on Oracle EBS and Oracle Alert mechanism. My understanding is that Oracle Alert works just like database trigger.
Will Oracle Alert fire when database updates/inserts happen from the back-end? We have observed alert is only firing for transactions front end and not running for back-end updates?
Is it guaranteed that just like a Trigger, EBS Alert will fire on every update to the record?
Yes, it is somewhat like a database trigger created from the Front-End Application. To explain further, there are two types of Oracle Alerts, Periodic and Event Alerts.
Take note that for Event Alerts, the triggering table must be setup in Oracle EBS' Application Object Library (called an Application Table).
No. Taking this line from Krishna Reddy:
To add more context, Oracle Alert is a simple and efficient way to give you an immediate view of the critical activities in your Oracle Application. It helps Business Users / Administrators be on top of important or unusual business events you need to know about via E-Mail. It can also automate a process depending on the user’s response.
Some weaknesses and limitations though, is that Oracle Alert cannot process rows up to more than around 50, and its Report Layout has a text-based design and does not support HTML. Also, the text width is also limited.
Check out the Oracle documentation and this good article about Oracle Alerts.