I'm using JakartaEE and making a "hello world" kind of restfulAPI, can't get a return string by visiting URL

Question

Providing every step I took with this short video: https://youtu.be/hbSr8sRYuOk

Project code here: https://github.com/LJonn/restapiHelloWorld

Running everything on a local server on tomcat.

I'm having this issue for quite some time and ran out of ideas where the problem might be... I tried URL's such as these: "http://localhost:8080/api/hello" and "http://localhost:8080/helloworld/api/hello" and expected one of these to work.

Running http://localhost:8080/manager/text/list shows that helloworld.war is deployed fine and working:
OK - Listed applications for virtual host [localhost]
/:running:0:ROOT
/helloworld:running:0:helloworld
/examples:running:0:examples
/host-manager:running:0:host-manager
/manager:running:0:manager
/docs:running:0:docs

So why I still get a HTTP Status 404 page? What could I try to do to find the issue?

These are my project's Maven dependencies:

  <dependencies>
    <dependency>
        <groupId>jakarta.platform</groupId>
        <artifactId>jakarta.jakartaee-web-api</artifactId>
        <version>9.1.0</version>
        <scope>provided</scope>
    </dependency>
  </dependencies>

Thanks to Nikos Paraskevopoulos comment it looks like changing from Tomcat to TomEE might fix the issue, but now I'm running into a problem where the .war file can't be deployed/started, probably some sort of versions compatibility issue, tomcat manager GUI gives this error when trying to start the .war file:

FAIL - Application at context path [/helloworld] could not be started
FAIL - Encountered exception [org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/helloworld]]]

Looking to manager logs It looks like it has something to do with annotations and Java 16 maybe?:

...
Caused by: java.lang.IllegalArgumentException: Unsupported class file major version 60
        at org.apache.xbean.asm7.ClassReader.<init>(ClassReader.java:195)
        at org.apache.xbean.asm7.ClassReader.<init>(ClassReader.java:176)
        at org.apache.xbean.asm7.ClassReader.<init>(ClassReader.java:162)
        at org.apache.xbean.asm7.ClassReader.<init>(ClassReader.java:283)
        at org.apache.xbean.finder.AnnotationFinder.readClassDef(AnnotationFinder.java:1176)
        ... 52 more
01-Sep-2021 15:25:02.185 INFO [http-nio-8080-exec-3] org.apache.catalina.core.ApplicationContext.log HTMLManager: list: Listing contexts for virtual host 'localhost'

I've tried to check JRE version on Eclipse and it's 16.0.2 and it looks to me that the same version is running on tomcat.

Just a guess… Try using `127.0.0.1` instead of `localhost` to avoid name resolution. Ex: `http://127.0.0.1:8080/helloworld` etc. — Basil Bourque, Aug 31 '21 at 15:38
both 127.0.0.1 and localhost works the same for me. Seems like tomcat is working properly and I can access its GUI if I run it via startup.bin, but ".../api/hello" URL doesn't return a string which I expect it to do.. — LuckyTriple Smile, Aug 31 '21 at 16:55
There are two issues I can think of: (1) you are using the `jakarta` APIs, are you sure you are using a version of Tomcat that supports it over `javax`? Please double check!!! (2) Is Tomcat supposed to pick up the JAX-RS application without an entry to the `web.xml`? Can you try again with an appropriate `` and `` for JAX-RS in the `web.xml`? — Nikos Paraskevopoulos, Sep 01 '21 at 07:44

score 2 · Accepted Answer · edited Oct 10 '21 at 20:43

Tomcat 10.0 and 10.1 are not full Jakarta EE 9.1 application servers: you shouldn't use the jakarta.jakartaee-web-api artifact, which would imply that the runtime supports all Jakarta EE 9.1 Web Profile technologies.

Tomcat does not implement all the specs required in Web Profile. At least four other products do. See this list for Jakarta Web Profile 9.1:

Apache TomEE
Eclipse Glassfish
IBM Open Liberty
Red Hat WildFly

You can find the list of supported technologies on Tomcat's web site and for Tomcat 10 they translate to this list shown as a Maven POM snippet.

    <dependency>
      <groupId>jakarta.servlet</groupId>
      <artifactId>jakarta.servlet-api</artifactId>
      <version>5.0.0</version>
      <scope>provided</scope>
    </dependency>
    <dependency>
      <groupId>jakarta.servlet.jsp</groupId>
      <artifactId>jakarta.servlet.jsp-api</artifactId>
      <version>3.0.0</version>
      <scope>provided</scope>
    </dependency>
    <dependency>
      <groupId>jakarta.el</groupId>
      <artifactId>jakarta.el-api</artifactId>
      <version>4.0.0</version>
      <scope>provided</scope>
    </dependency>
    <dependency>
      <groupId>jakarta.websocket</groupId>
      <artifactId>jakarta.websocket-api</artifactId>
      <version>2.0.0</version>
      <scope>provided</scope>
    </dependency>
    <dependency>
      <groupId>jakarta.security.auth.message</groupId>
      <artifactId>jakarta.security.auth.message-api</artifactId>
      <version>2.0.0-RC1</version>
      <scope>provided</scope>
    </dependency>

Since Servlet 3.0, additional Jakarta EE specifications can be added using the servlet pluggability mechanism. To use JAX-RS you need to add:

<dependency>
    <groupId>org.glassfish.jersey.containers</groupId>
    <artifactId>jersey-container-servlet</artifactId>
    <version>3.0.2</version>
</dependency>
<dependency>
    <groupId>org.glassfish.jersey.inject</groupId>
    <artifactId>jersey-hk2</artifactId>
    <version>3.0.2</version>
</dependency>

or an equivalent configuration using other JAX-RS implementations.

@LuckyTripleSmile For more details and a visual diagram, see [my Answer](https://stackoverflow.com/a/44132306/642706) on [*Java EE Web Profile vs Java EE Full Platform*](https://stackoverflow.com/q/24239978/642706). Tomcat & Jetty are focused on simply being a runtime environment for servlets and JSPs. So they support only a few of the dozens of specifications defined in Jakarta EE. Mainly: HTTP web server, Servlet, JavaServer Pages (JSP), Expression Language (EL), WebSocket, JNDI, Std tag lib. Jakarta EE really should define a “profile” for what Tomcat & Jetty implement, but never have. — Basil Bourque, Sep 01 '21 at 20:47

I'm using JakartaEE and making a "hello world" kind of restfulAPI, can't get a return string by visiting URL

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