It allows you to inject also OSGI services into your Sling Models.

the connection from AEM CS to your application takes a different route than the requests from your local machine to the backend. And that cause a variety of issues, starting from being blocked by a firewall (AEM probably acts from a different network than your local machine).

You posted 2 requirements:restrict PROD publish instance to internal traffic (from a certain IP range)not preventing the domain to load externally.I don't understand how these 2 requirements can be met at the same time, because they contradict each other (if you allow external access to the domain, ...

This is not a problem of AEM, but caused by custom code which tries to do a call to a different HTTP endpoint. If you just let the exception bubble up, the workflow step will eventually fail and retry (IIRC up to 3 times) before the workflow will eventually fail. (You might want to think about addin...

Hi, for ootb-provided JS-based Sling models it's of course not possible to enforce it; but thanks for the report, I will see that this one is replaced by a proper Java-based Sling Model. 

It really depends on the criteria: If you search a large subtree and you can formulate the criteria for the pages/assets you want to process in a query, go for the query.If on the other hand side you need to process (almost) every page/asset in a subtree, using the iteration can be faster. But you a...

What do you mean with "compress"? Does it relate to image (file) size or are you rather referring to dimensions (width/height)?

the exception trace will contain more information what exactly failed, and the error messages are normally quite helpful.

The most obvious reason for such an event handler to stop it got blocked because it took too much time. The OSGI implementation blocks event handlers which consume 5s of execution time per invocation. That means if you need to more complex operations or even external calls, you should delegate that ...