Currently trying to learn Java EE 8 (Workplace demand)

Made a separate maven project named “Shared”, that contains one @Statefull EJB to preserve, Messages.

MessageRepository.java

@Stateful
public class MessageRepository {

    public List<Message> messages = new ArrayList<>();

    public String saveMessage(Message message){
        messages.add(message);
        return "Message Sent!";
    }

    public List<Message> fetchMessages() {
        return messages;
    }
}

Message.java

public class Message implements Serializable {
    private String sender;
    private String content;
    private LocalDateTime timeStamp;
   
    // getters & setters
}

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.example</groupId>
    <artifactId>shared</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>ejb</packaging>

    <properties>
        <maven.compiler.source>22</maven.compiler.source>
        <maven.compiler.target>22</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>
        <!-- https://mvnrepository.com/artifact/jakarta.platform/jakarta.jakartaee-api -->
        <dependency>
            <groupId>jakarta.platform</groupId>
            <artifactId>jakarta.jakartaee-api</artifactId>
            <version>10.0.0</version>
            <scope>provided</scope>
        </dependency>

    </dependencies>

</project>

After this, I created a jar file of “Shared”, and inserted the <group>, <artifact> & <version> as dependency inside two other maven project’s pom.xml, named App-A & App-B. I’ve also deployed this shared.jar in Wildfly 33.

Now, the intention is:

1. App-A & App-B will send message to shared. Shared will save that message

2. App-A can see it's sent messages as well as App-B's messages.

3. App-B can see it's sent messages as well as App-A's messages.

Here is App-A’s classes:

@Path("/messages")
@Produces(MediaType.APPLICATION_JSON)
@Consumes(MediaType.APPLICATION_JSON)
@ApplicationScoped
public class App_AControllers {

    @Inject
    App_AService appAService;

    @GET
    @Path("/receive")
    public Response getMessages() {
        List<Message> messages = appAService.getMessages();
        return Response.status(Response.Status.OK).entity(messages).build();
    }

    @POST
    @Path("/send")
    public Response sendMessage(SendMessageDto sendMessageDto) {
        String response = appAService.sendMessage(sendMessageDto);
        return Response.status(Response.Status.OK).entity(response).build();
    }
}

public class SendMessageDto {
    private String sender;
    private String content;

    public SendMessageDto() {}

    public String getSender() {
        return sender;
    }

    public void setSender(String sender) {
        this.sender = sender;
    }

    public String getContent() {
        return content;
    }

    public void setContent(String content) {
        this.content = content;
    }
}

@ApplicationScoped
public class App_AService {

    @Inject
    MessageRepository messageRepository;

    public String sendMessage(SendMessageDto sendMessageDto) {
        Message message = new Message();
        message.setSender(sendMessageDto.getSender());
        message.setContent(sendMessageDto.getContent());
        message.setTimeStamp(LocalDateTime.now());

        messageRepository.saveMessage(message);

        return "Message Sent!";
    }

    public List<Message> getMessages() {
        return messageRepository.fetchMessages();
    }
}

App-B’s classes are similar, just name changes.

Issue:

1. App-A & App-B can send & receive their own messages.

2. App-A's messages aren't appearing in App-B's /receive, neither the vice-versa.

I tried implementing a Webclient approach, like inside App-A a client to call App-B’s /receive, but that failed to deploy.

I’m not very sure, how to keep messages of both apps, in “Shared”.

If in case a detailed look on the code is required here is the github repo – https://github.com/sandeepRoy/Learning-Java-EE/tree/main/Inter%20App

Please consider me a beginner in Java EE, as I’m from a Spring boot background.