Unable to integrate vertx-when with Vert.x application

[msmolyak]

I was not able to find a version of vertx-when available in a public Maven repository. Thus, I cloned the project and built it locally. To build it I had to switch from Java 7 to Java 8, which I did. The project is installed locally as "com.englishtown.vertx:vertx-when:4.0.0-SNAPSHOT".

I added this statement to my build.gradle:
compile "com.englishtown.vertx:vertx-when:4.0.0-SNAPSHOT"

I am able to run 'gradle install' or 'gradle fatjar' for my Vert.x applicationwritten in Groovy without any problems.

Here is the code, which gives me trouble:

package test
import org.vertx.groovy.core.eventbus.Message
import org.vertx.groovy.platform.Verticle
import org.vertx.java.core.Future
import com.englishtown.promises.WhenFactory
import com.englishtown.vertx.promises.WhenVertx
import com.englishtown.promises.When
import com.englishtown.vertx.promises.impl.DefaultWhenVertx

class ApplicationVerticle extends Verticle {

    def start(Future startedResult) {
        def config = container.config

        When when = WhenFactory.createSync();
        WhenVertx whenContainer = new DefaultWhenVertx(vertx, when);
        ...

I get a runtime error when trying to run either the ApplicationVerticle or the entire module.
On line When when = WhenFactory.createSync(); I get this error:

java.lang.NoClassDefFoundError: javax/inject/Provider

I found your post suggesting adding this line to Vert.x langs.properties

groovy=com.englishtown~vertx-mod-hk2~1.7.0:com.englishtown.vertx.hk2.HK2VerticleFactory

Adding this line causes another error when I try to run the Verticle (it has no effect on the module):

java.lang.NoClassDefFoundError: org/vertx/groovy/platform/Verticle

What is the proper way of integrating vertx-when with a Vert.x application?

[adrianluisgonzalez]

Apologies, the documentation is severely lacking. I'll take a pass on adding some getting started details. The main issue, is I always use when.java and vertx-when with DI (vertx-hk2 or vertx-guice) which provide the javax.inject jar

<dependency>
    <groupId>javax.inject</groupId>
    <artifactId>javax.inject</artifactId>
    <version>1</version>
</dependency>

Try adding this dependency.

vertx-when 4.0.0-SNAPSHOT is intended for use with vert.x 3. The vertx-mod-hk2 module is intended to be used with vertx-mod-when and vert.x 2 which is why you get java.lang.NoClassDefFoundError: org/vertx/groovy/platform/Verticle

[msmolyak]

What version of vertx-when do I need to use with Vert.x 2.1.5?
Do I still need javax.inject with it?
Do I need to change langs.properties file?

[adrianluisgonzalez]

For vert.x 2.x you should use:

<dependency>
    <groupId>com.englishtown</groupId>
    <artifactId>vertx-mod-when</artifactId>
    <version>3.0.1</version>
</dependency>

You still need the javax.inject jar.

Also, you should not use WhenFactory.createSync() if running in Vert.x. Instead you should use com.englishtown.vertx.promises.impl.VertxExecutor with WhenFactory.createFor(() -> executor)

[adrianluisgonzalez]

You only need to modify langs.properties if you want to use DI with vertx-mod-hk2 or vertx-mod-guice.

[msmolyak]

This is the version of README file for 3.0.1: https://github.com/englishtown/vertx-when/blob/57ff099eb08d41420b33c2fad531004976ddb1d9/README.md. There is nothing about VertxExecutors there. It mentions whenContainer, but provides no instructions on how to create it.

According to the current README page, VertxExecutor is for vertx-when 4.0.0, in which case I am confused sine you are advising me to use VertxExecutor with Vert.x 2.1.5, which uses vertx-when 3.0.1.

Anyway, I am trying the following code with vertx-when-3.0.1:

        When when = WhenFactory.createSync();
        DefaultWhenContainer whenContainer = new DefaultWhenContainer(container, when);

The code compiles, but I get a runtime exception:

groovy.lang.GroovyRuntimeException: Could not find matching constructor for:
 com.englishtown.vertx.promises.impl.DefaultWhenContainer(
org.vertx.groovy.platform.Container, com.englishtown.promises.impl.DefaultWhen)

DefaultWhenContainer expects org.vertx.java.platform.Container. Does it mean it cannot be used with Groovy? Is there a way to make vertx-when work with Groovy?

[adrianluisgonzalez]

It requires the Java instances. However, you should be able to do something like the following:

package com.englishtown.vertx.examples

import com.englishtown.promises.When
import com.englishtown.promises.WhenFactory
import com.englishtown.vertx.promises.impl.DefaultWhenContainer
import com.englishtown.vertx.promises.impl.VertxExecutor
import org.vertx.groovy.platform.Verticle

class WhenExampleVerticle extends Verticle {

    def start() {

        org.vertx.java.platform.Container container = getContainer().jContainer;
        org.vertx.java.core.Vertx vertx = getVertx().toJavaVertx();

        VertxExecutor executor = new VertxExecutor(vertx);
        When when = WhenFactory.createFor({
            return executor
        });

        DefaultWhenContainer whenContainer = new DefaultWhenContainer(container, when)

    }

}

I'm not sure if there is a better way to get the org.vertx.java.platform.Container instance, this is peeking at the private jContainer field.

[adrianluisgonzalez]

I thought I'd put together an example project: https://github.com/adrianluisgonzalez/vertx-when-groovy-example

I am not a groovy dev so I have no idea what I'm doing here.... Please feel free to comment if you have any suggestions.

[msmolyak]

Thanks, Adrian, the example was very useful.