Java Community | Help. Code. Learn.•10mo ago

Please explain what is this project is about (Multi Module Java Project)?

I have no idea what's going on here with the ejb, cor, web and stuff and the purpose of this project.

70 Replies

JavaBot•10mo ago

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Rag...JN 🌌 🦡 👽 💰 🐊OP•10mo ago

webmulti3.zip

dan1st•10mo ago

ok so you have multiple modules You can imagine each of these modules as its own Maven project But - When building the top module, it builds all of the modules - Modules can be dependencies of each other

Rag...JN 🌌 🦡 👽 💰 🐊OP•10mo ago

ok alright

dan1st•10mo ago

e.g. the web module uses the core module

Rag...JN 🌌 🦡 👽 💰 🐊OP•10mo ago

I want to run the app Is it same like running with adding a the server ?

dan1st•10mo ago

Rag...JN 🌌 🦡 👽 💰 🐊OP•10mo ago

like this

Rag...JN 🌌 🦡 👽 💰 🐊OP•10mo ago

it has 4 artifacts

dan1st•10mo ago

you probably need one of the web ones actually I think you need one of the ear ones

Rag...JN 🌌 🦡 👽 💰 🐊OP•10mo ago

ok let me try no it can't only the war alright I managed to run it I needed to use GlassFish instead of Payara @dan1st | Daniel forgive me for the ping But what subject is this, so I can learn about it

dan1st•10mo ago

Jakarta EE deployments essentially WAR and EAR are special JAR files that can be deployed to Jakarta EE servers

Rag...JN 🌌 🦡 👽 💰 🐊OP•10mo ago

How about these annotations and stuff

dan1st•10mo ago

WAR = web application archive EAR = enterprise application archive (I think) which annotations specifically?

Rag...JN 🌌 🦡 👽 💰 🐊OP•10mo ago

The stateless in package jakarta.ejb

dan1st•10mo ago

it's a Jakarta EE annotation: https://jakarta.ee/specifications/platform/11/apidocs/jakarta/ejb/stateless

Stateless (Jakarta EE Platform API)

declaration: package: jakarta.ejb, annotation type: Stateless

Rag...JN 🌌 🦡 👽 💰 🐊OP•10mo ago

I have no clear idea where to start still. So I will try with Jakarta EE deployments ?

dan1st•10mo ago

I mean, I guess you generally want to get an idea about Jakarta EE I think information on stateless itself can be found in the spec here: https://jakarta.ee/specifications/enterprise-beans/4.0/jakarta-enterprise-beans-spec-core-4.0#stateless-session-beans

Rag...JN 🌌 🦡 👽 💰 🐊OP•10mo ago

alright sir

JavaBot•10mo ago

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Rag...JN 🌌 🦡 👽 💰 🐊OP•10mo ago

why this can't be in just the main project's src or just inside the web project packages? you create a package called core for interfaces and ejb for interface implementation and use them inside the controllers

dan1st•10mo ago

could be maintainability it's easier to maintain multiple smaller modules than one big module in many cases

Rag...JN 🌌 🦡 👽 💰 🐊OP•10mo ago

alright alright that make sense

dan1st•10mo ago

or you could have a client and a server and they share some code so you create 3 modules - one for the common code, one for the server and one for the client - then the client doesn't contain the server code and vice-versa or you could have different teams working on different modules

Rag...JN 🌌 🦡 👽 💰 🐊OP•10mo ago

Inside the web moduel's pom.xml

Rag...JN 🌌 🦡 👽 💰 🐊OP•10mo ago

So this plugin does this

The WAR Plugin is responsible for collecting all artifact dependencies, classes and resources of the web application and packaging them into a web application archive.

So only what's inside the web module gets packaged?

dan1st•10mo ago

the war plugin essentially creates the WAR file

Rag...JN 🌌 🦡 👽 💰 🐊OP•10mo ago

but here the core module also used as a dependency it will be packaged as well?

Rag...JN 🌌 🦡 👽 💰 🐊OP•10mo ago

dan1st•10mo ago

and for that, it uses the dependencies of the same module and the code in that module ofc

Rag...JN 🌌 🦡 👽 💰 🐊OP•10mo ago

So what if I used the web module as a dependency inside the core module as well? will there be an exception occur

dan1st•10mo ago

then you have circular dependencies so yes because web requires core which requires web

Rag...JN 🌌 🦡 👽 💰 🐊OP•10mo ago

core ----pom.xml ================= dependency -> has web module web ---pom.xml ================ dependency -> has core module alright ok got it

dan1st•10mo ago

However, it might be possible as a test dependency but I didn't test that (pun intended)

Rag...JN 🌌 🦡 👽 💰 🐊OP•10mo ago

what is this section (the right bar) I only declared one plugin but the bar has multiple plugins?

Rag...JN 🌌 🦡 👽 💰 🐊OP•10mo ago

the core plugins

dan1st•10mo ago

These are plugins Maven adds by default

Rag...JN 🌌 🦡 👽 💰 🐊OP•10mo ago

dan1st•10mo ago

For example the compiler plugin compiles your application Also you have a <parent> element, right?

Rag...JN 🌌 🦡 👽 💰 🐊OP•10mo ago

yah

dan1st•10mo ago

almost all configuration from the <parent> is copied to the child and there's kinda a default parent which isn't really shown and you can also add stuff to the POM via profiles

Rag...JN 🌌 🦡 👽 💰 🐊OP•10mo ago

oh shit I removed the maven-war-plugin and now the war core plugin is gone So the remaining are the default core plugins

dan1st•10mo ago

You can execute the command mvn help:effective-pom and it should show you the POM after these things have been applied Do you have a <packaging> tag?

Rag...JN 🌌 🦡 👽 💰 🐊OP•10mo ago

yep

dan1st•10mo ago

ok I thought that should add the maven-war-plugin by default but maybe it's just IntelliJ not showing it

Rag...JN 🌌 🦡 👽 💰 🐊OP•10mo ago

no no I added it default (followed the sample project)

dan1st•10mo ago

I meant that Maven should implicitely add it if you don't

Rag...JN 🌌 🦡 👽 💰 🐊OP•10mo ago

alright module ejb's pom.xml

    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>com.jiat</groupId>
        <artifactId>webmulti</artifactId>
        <version>1.0</version>
    </parent>

    <artifactId>ejb</artifactId>
    <packaging>ejb</packaging>

    <properties>
        <maven.compiler.source>11</maven.compiler.source>
        <maven.compiler.target>11</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>
        <dependency>
            <groupId>jakarta.platform</groupId>
            <artifactId>jakarta.jakartaee-web-api</artifactId>
            <version>10.0.0</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>jakarta.ejb</groupId>
            <artifactId>jakarta.ejb-api</artifactId>
            <version>4.0.1</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>com.jiat</groupId>
            <artifactId>core</artifactId>
            <version>1.1</version>
            <type>jar</type>
        </dependency>

    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-ejb-plugin</artifactId>
                <version>3.2.1</version>
            </plugin>
        </plugins>
    </build>

    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>com.jiat</groupId>
        <artifactId>webmulti</artifactId>
        <version>1.0</version>
    </parent>

    <artifactId>ejb</artifactId>
    <packaging>ejb</packaging>

    <properties>
        <maven.compiler.source>11</maven.compiler.source>
        <maven.compiler.target>11</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>
        <dependency>
            <groupId>jakarta.platform</groupId>
            <artifactId>jakarta.jakartaee-web-api</artifactId>
            <version>10.0.0</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>jakarta.ejb</groupId>
            <artifactId>jakarta.ejb-api</artifactId>
            <version>4.0.1</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>com.jiat</groupId>
            <artifactId>core</artifactId>
            <version>1.1</version>
            <type>jar</type>
        </dependency>

    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-ejb-plugin</artifactId>
                <version>3.2.1</version>
            </plugin>
        </plugins>
    </build>

questions 1. why ejb uses web api 2. why core module is used as a jar type dependency 3. what's up with the ejb plugin

dan1st•10mo ago

why ejb uses web api

tbh I don't know - but I guess it's so that when you deploy the EAR, everything from the web package should be included as well

why core module is used as a jar type dependency

jar is the default - if you just want to use something as a library/used by other things OR if you want to execute it with java -jar, you'd normally use jar

what's up with the ejb plugin

I think that's responsible for the EAR file but I have never worked with EJB/EAR stuff

Rag...JN 🌌 🦡 👽 💰 🐊OP•10mo ago

hope me neither 😆

Rag...JN 🌌 🦡 👽 💰 🐊OP•10mo ago

probably this

dan1st•10mo ago

and I think this creates an EAR file in the package phase

Rag...JN 🌌 🦡 👽 💰 🐊OP•10mo ago

I will first study about EJB and then EAR ^

dan1st•10mo ago

idk how helpful the spec is for that

Rag...JN 🌌 🦡 👽 💰 🐊OP•10mo ago

I will see i am going to eat now

dan1st•10mo ago

You might be more successful with tutorials or blog posts about it the spec is probably more useful for reference or if you want to implement a server

Rag...JN 🌌 🦡 👽 💰 🐊OP•10mo ago

What does it mean by local and remote It's something with RMI?

dan1st•10mo ago

where does it say that? local typically means on the same device and remote typically means on a different one

Rag...JN 🌌 🦡 👽 💰 🐊OP•10mo ago

Starting from line 8

dan1st•10mo ago

ah there I looked over that yeah local network access means things on the same computer (or maybe things in the same network) and remote means communicating with other servers or similar

Rag...JN 🌌 🦡 👽 💰 🐊OP•10mo ago

yah but why it matters when you run a server? oh wait no stupid question

dan1st•10mo ago

I mean, idk much about EJB As I said, maybe check introductory articles orr similar maybe there are some freely available books as well if you are into books

Rag...JN 🌌 🦡 👽 💰 🐊OP•10mo ago

ah ok btw any idea if I can do this tutorial in a plain ant project? https://www.javatpoint.com/RMI

www.javatpoint.com

Remote Method Invocation (RMI) - javatpoint

Remote Method Invocation (rmi) is an API that provides a mechanism to create distributed application in java.

Rag...JN 🌌 🦡 👽 💰 🐊OP•10mo ago

ok I downloaded the project

JavaBot•10mo ago

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Please explain what is this project is about (Multi Module Java Project)?