[vbsteven]

Implementing simple middleware in Spring (boot) is pretty much the same. One class with one method that has access to req, res and the next filter. The @Component annotation is all it takes to enable the filter in your web stack.

  @Component
  public class MyMiddleware extends OncePerRequestFilter {
  
      @Override
      protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException {
          // your code
          filterChain.doFilter(request, response);
      }
  
  }

[hardwaresofton]

I think this is a good example of the difference in complexity grades of both langauges/frameworks. That spring boot example is indeed pretty simple (for java), but to understand it, here's what I'm pretty sure has to happen:

1. Set up your spring boot project properly

2. Set up all the XML that supports your beans properly

3. Know how and when to use @Component

4. Know that OncePerRequestFilter exists, and/or to extend it, which method to override

5. Know to call filterChain properly

Most of these are trivial with some IDE support and maybe a templating school, and probably not even an issue after your second week with Spring boot (or spring in general), and it's an improvement over what life used to be like but compare this with the general jist of how to do it in JS:

1. set up expressjs properly (usually a two-liner). It won't have things like @Cachable that spring boot provides to you out of the gate, but it generally has enough to get you up and serving requests.

2. Know what req/res are (the fact that calling res.send(...) sends stuff and .ends as well is arguably nontrivial) and how to use next

3. Know what a function is.

the code snippet I'm thinking of is:

    app.use(function(req, res, next) {
      // your code
      next();
    })

It is "pretty much" the same, but how much work it is really depends on who you ask -- you can get up to speed with a simply built expressjs app in tens of minutes (many express apps follow a very simple setup pattern), but I've never seen that happen in a spring boot app for an absolutely fresh developer, even worse if the codebase is transitioning from spring to spring boot or has some other hacks in it.

Spring Boot is marvelously simple one of it's best parts (it almost makes me want to use Java for a greenfield project), but there's so much noise in that code -- it should just be a function -- IMO all started with the decision in 1.1 (??) to choose Runnable over lambdas. Most of the complexity I'm ribbing Java over is just due to how you write the langage -- java on it's simplest day just can't be as simple as some of the stuff that came after it, since they had the benefit of hindsight.

[vbsteven]

1. setting up a Spring Boot project is just File/New Project/Next/Next/Next, or download a starter project from https://start.spring.io

2. It's 2018, we don't use XML anymore, a Main class annotated with @SpringBootApplication is all the configuration you need (and autogenerated by step 1)

3. All you need to know about @Component before you get started is if you annotate a class with it, it will get instantiated with all its dependencies and made available for use in the container

4./5. Yes, to know about Filter, the filterChain and how to use it might take some minutes looking into the documentation or stack overflow, but that is what you are going to have to do anyway if you are going to use a framework.

I put knowing how to use @Component and figuring out what you need from the docs on the same level as knowing about the (req, res, next) pattern and knowing about async/callbacks/promises.

I agree that Java is verbose and has much ceremony but modern IDE's take away a lot of that pain. For my filter example the only things I typed are:

* the class name

* extends OPRF<tab>

* <alt><enter> <enter> to generate the 1 method to implement

* the `// your code` comment and filterChain.doFilter()

I'm not sure what you mean about choosing Runnable over lambdas. Runnable `is` a functional interface so anywhere you can use a Runnable, you can pass a lambda (or method reference)

[jacques_chester]

I find setting up the toolchain for Javascript projects to be an exercise in torture, toil and tears, so it's not quite as simple as all that.

Meanwhile I can get to a running Spring Boot app in quite literally seconds.

The difference is that I know something about Spring Boot and much less about Node. That says nothing about either of them.