Service Component missing in AEM - eclipse

Question

I am trying to create a project in Eclipse using the AEM Developer Tools plugin. The project is published in AEM server and can be seen in: Websites and CRXDE Lite.
The project was created using Maven Archetype-10 in Eclipse and the default project has two pages in English and French. When I open the page in the Site URL, I get the end page, where the message from the HelloWorldModel class should be displayed, along with the other text. But I don't get the message from the respective class. Instead, I am getting the following error message:
org.apache.sling.api.scripting.ScriptEvaluationException: org.apache.sling.scripting.sightly.SightlyException: Cannot find a a file corresponding to class com.pen.mypen.core.models.HelloWorldModel in the repository.
It looks like the Java files in the CORE project are not published or are not visible to the web page. But the 3 packages: Core, Apps, and Content are all published and synchronized in Eclipse. Is there any way to check if the Java package is deployed to AEM server? Please guide me to what I am missing here. Please find the error stack trace below:
Caused by: org.apache.sling.scripting.sightly.SightlyException: Cannot find a a file corresponding to class com.pen.mypen.core.models.HelloWorldModel in the repository.
at org.apache.sling.scripting.sightly.impl.compiler.SightlyJavaCompilerService.compileRepositoryJavaClass(SightlyJavaCompilerService.java:212)
at org.apache.sling.scripting.sightly.impl.compiler.SightlyJavaCompilerService.getInstance(SightlyJavaCompilerService.java:113)
at org.apache.sling.scripting.sightly.impl.engine.extension.use.JavaUseProvider.provide(JavaUseProvider.java:127)
at org.apache.sling.scripting.sightly.impl.engine.extension.use.UseRuntimeExtension.call(UseRuntimeExtension.java:84)
at org.apache.sling.scripting.sightly.impl.engine.runtime.RenderContextImpl.call(RenderContextImpl.java:66)
at org.apache.sling.scripting.sightly.apps.pen.components.content.helloworld.SightlyJava_helloworld.render(SightlyJava_helloworld.java:53)
at org.apache.sling.scripting.sightly.impl.engine.runtime.RenderUnit.render(RenderUnit.java:54)
at org.apache.sling.scripting.sightly.impl.engine.SightlyScriptEngine.evaluateScript(SightlyScriptEngine.java:92)
at org.apache.sling.scripting.sightly.impl.engine.SightlyScriptEngine.eval(SightlyScriptEngine.java:78)
at org.apache.sling.scripting.core.impl.DefaultSlingScript.call(DefaultSlingScript.java:388)
UPDATE
AEM - 6.2
Eclipse - Luna
Java - 1.8

Answer 1

You can check the following things:
http://SERVER:PORT/system/console/bundles shows all the java bundles that are installed on your AEM machine. Check if your bundle is listed there. If not then it could not be installed => check the error log
If your bundle is listed there, check if it is status is active, if not there might be missing dependencies or stuff like that. => click the bundle name to see more details what went wron, also check the error log.
If the status is active, click on the bundle and see if the package that contains your java class is listed in the Exported Packages section.
If the package is listed, you might need to check the error log (again).
UPDATE (because of AEM 6.2):
The problem with your project is, that with AEM versions prior to 6.2, there was a dependency to javax.inject version 0 whereas now they need version 1 and that's not reflected in the pom.xml.
Just add this to your pom.xml of the core project - that's the only change you'll have to do:
<dependency>
<groupId>javax.inject</groupId>
<artifactId>javax.inject</artifactId>
<version>1</version>
</dependency>
and everything will work. Sorry for the confusion...

Answer 2

In case you are using SlingModels the javax.inject is exposed by the org.apache.sling.models.api
Can you check your pom for the SlingModel dependencies
<dependency>
<groupId>org.apache.sling</groupId>
<artifactId>org.apache.sling.models.api</artifactId>
<version>VERSION_NUMBER</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.apache.sling</groupId>
<artifactId>org.apache.sling.models.impl</artifactId>
<version>VERSION_NUMBER</version>
<scope>provided</scope>
</dependency>
Check the VERSION_NUMBER you are using and then in /system/console/bundles verify that the same version bundle is present and Active.
With AEM 6.x the Sling Model bundles are available by default. The 6.0 will have a lower version 1.0.x. Fixing the version either by updating the pom or installing the SlingModel bundles with version VERSION_NUMBER fix your issue.
Update for 6.2
For 6.2 with models with version 1.2.2 use following in dependencies -
<dependency>
<groupId>org.apache.sling</groupId>
<artifactId>org.apache.sling.models.api</artifactId>
<version>1.2.2</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.apache.sling</groupId>
<artifactId>org.apache.sling.models.impl</artifactId>
<version>1.2.2</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.apache.geronimo.specs</groupId>
<artifactId>geronimo-atinject_1.0_spec</artifactId>
<version>1.0</version>
<scope>provided</scope>
</dependency>
geronimo-atinject_1.0_spec is the one that is exposing javax.inject in sling models 1.2.2

Answer 3

Sharing my solution which will be helpful.
Tested on AEM 6.2 working perfect.
In core pom.xml file add Import-Package tag with "javax.inject;version=0.0.0,*" inside "org.apache.felix" plugin tag.
Following is the sample :
<plugin>
<groupId>org.apache.felix</groupId>
<artifactId>maven-bundle-plugin</artifactId>
<extensions>true</extensions>
<configuration>
<instructions>
<!--
<Embed-Dependency>
artifactId1,artifactId2;inline=true
</Embed-Dependency>
-->
<!-- Import any version of javax.inject, to allow running on multiple versions of AEM -->
<Import-Package>javax.inject;version=0.0.0,*</Import-Package>
<Sling-Model-Packages>
com.next.sample_test_impl.core
</Sling-Model-Packages>
</instructions>
</configuration>
</plugin>