Comment by dhosek 3 days ago
I used to joke that the direction spring was heading was that you’d have an application be a boilerplate main method with a dozen lines of annotations. Then I actually encountered this in the wild: we had an app that sent updates from db2 to rabbitmq, and the application literally was just configuration via annotations and no actual Java code other than the usual spring main method.
I think the general adversity against this specialized configurations is that they often tend to be fairly limited/rigid in what they can do, and if you want to customize anything you have to rewrite the whole thing. They effectively lock you into one black box of doing things, and getting out of it can be very painful.
Spring boot just provides what they think are reasonable defaults and you provide some specifics.
You can always inject your own implementation if needed right?
Spring is written by a committee of junior developers trying to implement the ideas from a committee of slightly less junior developers. Which is to say it's a huge unintelligible mess. As the other commenter attest, it works really well if you need the one thing it does - unfortunately the moment you need something slightly different you are forced to dig deep into the insane internals and it is a disaster. This moment comes very quickly too in every project because it was written by people with no experience in real projects.
Oh, I think it’s quite wonderful really. There are cases where the limited nature of some configuration-based things ends up being a mess (one that comes to mind is a feature in Spring Data where you can extend a DAO bean into a rest service through annotations, but it turns out that this feature (at least when I last tried working with it), is so rigid as to be nearly useless in actual practice. But our codeless application was a bit of brilliance, I think.
this is exactly why spring succeeded. I need to run a scheduled job, @EnableScheduling then @Scheduled(cron = “xxxxxx”) - done. I need XYZ, @EnableXYZ the @XYZ… sh*t just works…
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.
> env specific properties
And then if you want to change a value at runtime you have to restart the executable?
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.
So…pass that variable to your annotation.
I’m not seeing the point?
Yeah, it works until it isn't. And they good luck debugging it. I'd prefer simple obvious linear code calling some functions over this declarative magic any day.
cronService.schedule("xxx", this::refresh);
never had any issues debugging as I am never debugging the scheduler (that works :) ) but my own code.
and what exactly is “cronService”? you write in each service or copy/paste each time you need it?
You can write your own libraries?
My goodness. What a question!
Then you need to deploy it on multiple nodes and neex to make sure it only runs once for each run of the cron, etc.
I believe Quartz is the go-to solution for this. It's not part of Spring but it offers a similar annotation-driven interface, but with distributed locking via a database
Is that strictly bad, though? Being able to run an enterprise service by setting configuration values declaratively, and get all the guarantees of a well-tested framework, seems like a pretty good thing.
Yes, it’s weird how that’s still Java, but using standard components and only using code as glue where it’s absolutely necessary seems very similar to other engineering disciplines to me.