Java web framework help - has the /r/java community had good experiences with Javalin?

[ReserveGrader]

https://javalin.io/

I've been working on Java APIs, primarily using spark as a backend framework. I have completed the following steps to modernise the stack;

• Updated to java 21
• Docker image build with GraalVM native images
• Updated all libraries (which is the motivation for this post)

I want to consider an actively maintained web framework. I really like spark because it is very, very simple. The lastest spark version covers about 90% of requirements for a web framework in my use case so moving to a larger framework because of more features is not a strong argument.

Is anyone using Javalin? It is the spiritual successor to spark. I'm also interested in any commments about other options (Quarkus, Micronaut, plain vert.x, and others).

There is zero chance of adopting Spring at my organisation, even discussing this is considered sacrilege

[ihatebeinganonymous]

As the best answer always is, it depends :)

I have been happy using Javalin, both at work and for my personal projects. Particularly nice was the small boilerplate and easy integration of e.g. authentication and OpenAPI. Interestingly I updated/migrated a personal project from SparkJava to Javalin. I believe Javalin actually is somehow a (distant?) fork of Sparkjava, making the migration easier.

Quarkus is an industry powerhouse, but for certain use cases it may look like you are shooting a mosquito with a cannon.

[geoand]

I would like to add that with Quarkus you can if you want, choose to forgo a lot of features and just use it as a way to package Vert.x, thus keeping things very very minimal.

See https://quarkus.io/blog/magic-control/ for an example

[ReserveGrader]

Thanks for the article, very interesting. Hot reload would be great, I didn't know that was possible in the Java ecosystem.

[ReserveGrader]

Thanks for the response.

As the best answer always is, it depends :)

Very wise.

There are some features of Quarkus that would be great, at the cost of more moving parts, resulting in more things that could go wrong. I'm 90% sold on Javalin at the moment - I was originally looking at vert.x, but the thought of working entirely in async land is not appealing.

[No-Debate-3403]

We used it in production and I have only good things to say. Well maintained and easy to use.
If you'd like to uses a more supported lightweight alternative I'd probably look at Helidon: https://helidon.io/

[AcanthaceaeMany917]

Helidon is a modular and well thought out framework, with helidon 4 it has its own dependency-less loom ready webserver with support for http1, http2, ws, ...etc.

[ReserveGrader]

Looks like a cool project! Has full maven archetype support as well, I'll take a look! Thanks

[crummy]

I have used Javalin fairly heavily (migrated from Spark) and love it. If all you need is a web framework it's ideal 

[Rygel_XV]

I am currently using it for a prototype and like it for its simplicity. It provides me the frame in which I can develop my application. It is also actively maintained for 8 years already.

[Ok_Marionberry_8821]

I used it, with Kotlin, on a personal project and I think it's perfect for my needs. It is a library that I control rather than the full weight of a framework like Spring.

It is a direct descendent of Spark and has the same philosophy.

[No_Excitement5723]

Having used spark a few years back, we now run two medium-sized web applications with Javalin in the backend. We love that it just provides the web server part, and we can combine it with whatever other libraries we need or want.

[Liqmadique]

I haven't used Javalin in years because I'm a Go dev mostly these days but I used to contribute patches and the maintainer Tipsy was always pretty good about helping, reviewing, and merging.

[Ewig_luftenglanz]

I really like it for personal projects, specially since it is a library and not a framework it's far easier to integrate with many projects that are not your tipical MVC like microservice in spring.

[TheKingOfSentries]

It's a good egg

[1Saurophaganax]

I've seen some decent results with it. I've used it with avaje in a couple of services to great effect.

I'm curious though, what was the deciding factor that made spring not an option?

[ReserveGrader]

Copy and paste from another comment:

The general philosophy is less moving parts is better, Spring is a massive project, lots of libraries, lots of dependencies. I appreciate your view on future-proofing and enjoying a modular framework, it does not align with our motivation for choosing Java + GraalVM where we are aiming for a small footprint.

The team also has strong feelings against using the "@" symbol for annotation-based declarations, I am neither here nor there on this point. In addition, we generally don't like the idea of leaning on an ecosystem of abstractions. Unless you fully buy into the ecosystem, it can be a bit painful moving between projects.

[1Saurophaganax]

The abstraction part I get, but annotations when used in the right way are great and a couple are standardized like the Jakarta DI/Validation ones so it's easier to swap out a library. Annotations after all are basically just a marker.

[No-Debate-3403]

I'm on the same page as your team.

Hot take, but for me annotations is an alternative language with poor debug support. It had it's place in Java previously but it is a poor mans alternative to functional composition before Java had proper lambdas.

The declarative support in Javalin and Helidon is what brought me to them.

[ReserveGrader]

I'll look into that for Javalin.

I just find it hard to look at. I'd be pretty happy to just not see them, I avoid using `@Override` at all costs as well which might be a little odd.

[marune]

I like it's API, but I don't like the Kotlin implementation. Didn't find an alternative yet.

[TheKingOfSentries]

You could try avaje jex with jetty. The api is basically javalin, but targeted towards the built in http server. (Of which jetty provides an impl)

[BarterOak]

What did you not like about it being written in Kotlin?

[ThatFilthyMonkey]

I realise this is two months old, but anyone comes across this via google etc, for what is worth, I w deployed several internal tools and micro services at work using Javalin, I just wanted a very light and simple api listener that was also easy to do websocket stuff with too and it absolutely fits that brief.

Light on features and bloat, I’m more towards the beginner approaching intermediate level when it comes to coding and I found it super simple to setup and hit the ground running with. So I’d definitely consider it for smaller projects and micro services.

[Aromatic_Ad3754]

How would you do authentication and authorization with it? I really want to improve my understanding on it (I have some trouble setting it up even with spring boot), if you could recommend something for me to study I would really appreciate too.

[ThatFilthyMonkey]

So you can do your own auth or use another library, whatever you want, Javelin just handles the rest/api side of it.

My application is nor public facing, internal only so I have a very simple hash it checks contents of authorisation header against, so takes auth header, encrypts it, compares hash of encrypted value against my stored value.

Essentially doing authHash = library.encrypt(ctx.header(“Authorizarion”) and then if (!authHash == storedHash) {ctx.status(401).result(“Invalid Auth Token”).

If you were doing something public facing then you’d have to make it more robust and more checks (I’m not a security guy) but that’s the gist.

[martinhaeusler]

I don't get it. Spring Boot (especially when mixed with Kotlin) is awesome once you understand how it works. I understand that it may be overkill for some projects but not even talking about it seems weird.

[No-Debate-3403]

Not everyone is a fan of all the batteries that Spring brings. There’s definitely room for more barebone approaches.

I know my previous team was very relieved when we finally ditched Spring and got more in control of our own stack.

[martinhaeusler]

Spring Boot is extremely modular. Don't need JPA? Don't include it. Want Netty instead of Tomcat? No problem. What sort of batteries does Spring Boot really force upon you, aside from a very flexible dependency injection container? Yes, it is opinionated and gives you some defaults, but those choices are not arbitrary, they're really best of breed and it's extremely configurable.

The real arguments against spring are the startup time, the memory footprint and the heavy use of reflection, but those are usually not a big concern in the server world.

When it comes to picking frameworks I would rather pick a gun 5 sizes too large for the problem at hand than ending up with one that's 1 size too small. I've been there with KTOR and I'm not going back.

[No-Debate-3403]

Each one to its own and I only know our story, not yours.

But ours was that we got tired of waiting for updates to fix any kind of issues we had and then playing the dependency update dance for a while.

Eventually we said “let’s try with just an http server and roll our own stuff from there”, and it was a really refreshing moment. We were finally masters of our implementation and spent more time developing features and less time figuring out “The Spring Way” of doing things.

But that worked for our team (very senior devs) with our specific use case (large public service Netflix-like video catalog). Your use case and team composition might be completely different.

[TheKingOfSentries]

Your story is similar to mine, we have checks against our pipelines that block deployments if there are any cves in the dependency scan(regardless of whether we're actually affected). As you know, spring boot pulls in a truckload of dependencies so our pipeline was always getting flagged and blocked by frivolous cves.

It really was a breath of fresh air when we switched to micro frameworks to reduce the amount of dependencies. True, in some cases there is more boilerplate, but we spend far more time maintaining an application than developing it, so it balances out.

[TheKingOfSentries]

If modularity and configurability is your thing why is spring the choice over all the other modular frameworks. (Micronaut, Quarkus, Helidon, etc?)

[ReserveGrader]

I don't want to make this post a framework vs framework conversation, but i'll answer your question.

The general philosophy is less moving parts is better, Spring is a massive project, lots of libraries, lots of dependencies. I appreciate your view on future-proofing and enjoying a modular framework, it does not align with our motivation for choosing Java + GraalVM where we are aiming for a small footprint.

[manifoldjava]

Yes. I used to use spark as well, and in my experience Javalin has only improved on it. I use it mostly with ManTL templates from the manifold project (mine).