Comment by taftster
3 days ago
And then I realize I need to change that schedule. And would like to do it without recompiling my code. Oh, and I need to allow for environment specific scheduling, weekdays on one system, weekends on others. And I need other dependencies that are environment specific.
I much prefer Spring's XML configuration from the old days. Yeah, XML sucks and all that. But still, with XML, the configuration is completely external from the application and I can manage it from /etc style layouts. Hard coding and compiling in dependency injection via annotations or other such behaviors into the class directly has caused me grief over the long term pretty much every time.
I do realize you were intending to give examples of why you don't think annotations aren't very extensible, but it is an odd example as all those things can still be achieved via annotation, since the annotations can accept values loaded from env specific properties.
Exactly this, it’s great fun to have a surface level understanding of a topic and post derisively for internet points; rather then spend the time and effort to actually learn about the subject at hand!
I'm not digging for "internet points". Yes, superficial replacement values can be retrieved from the environment. But I guess we have to give you a more imagined or sophisticated example then to make the point to you?
How about varying implementations of a service interface. Let's say I have a Scheduler interface and I want to have multiple implementations; maybe one is CronScheduler, another is RandomScheduler, another is BlueMoonScheduler. Each of these schedulers have their own properties and configuration values. I might want to choose, per environment or deployment context, which service implementation to use.
Annotation configuration makes this (near?) impossible to dynamically wire and configure these scenarios and make them tailored to the environment or deployment scenario. Annotations are generally "static" and do not follow a configuration-as-code approach to application deployment.
An external configuration file, as offered by Spring's original (less "favored") XML style, allowed a more composable and sophisticated configuration-as-code approach. Maybe that's a negative, putting that much power into the hands of the service administrator. But as I stated originally, in my experience, having statically defined annotation driven configuration and/or dependency injection has caused more problems than it has solved.
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> env specific properties
And then if you want to change a value at runtime you have to restart the executable?
Most web application servers work this way. It also works really well in practice using modern CD tools - update your configuration and perform a gradual rollout of all your application servers to reflect the updated configuration.
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I have to deal with this at work for rolling db credentials, actuator refreshes are fine for this purpose.
Would be nicer if we could handle creds like it wasn't 1992, but this does the job too.
The only real-world usage I see for annotations are in GSON (the @Expose) and JUnit with @Test.
Never really came across with any other real cases where it solves a pressing issue as you mention. Most times is far more convenient to do things outside the compiled code.
Agreed. These are good examples where annotations seem like a good fit. Being able to tell a processor that a method or field is "special". Test methods, serializable hints, etc.
It's kind of like, when annotations were delivered to Java, lots of projects thought they were just the next greatest thing. I followed right along at the time, as well.
But over time, finding the value in the configuration-as-code approach to application deployment, I definitely feel that annotations have been abused for many use cases.
all trivial things you are listing, every single one…
So…pass that variable to your annotation.
I’m not seeing the point?
You do know about environmental variables?