How can I create (deploy) multiproject?

Question

I have three pools(apps) that transform data sequentially and communicate with each other by socket (or get, post - nevermind). And I have servlets, that accept data and transfer data to one of the starting pool. How can I run it all in one container (tomcat, wildfly)? Make 3 jar, 1 war artifact or something else? that should be written in the pom.xml?

Answer 1

Well, communication between the modules is important:

• If you are content with them communicating by direct, local API invocation, you must necessarily build one single war containing the three modules (typically one JAR for each module).

• But if you want a distributed application, the communication should be remote (either through TCP sockets, RMI, HTTP, ReST, etc). In this way, you may build one assembly for each module: It should be a WAR if the module contains servlets/JSPs, or a JAR if it does not.

In Maven, this translates to:

1. Create a parent project which contains all of the modules, with packaging=pom, and one <module> declaration for each module.
2. Then, create a module project (within the parent) for each module, with package=jar or war (depending on the above decission).
3. Set the proper dependencies between them in case you need to expose their public APIs as the way to inter-communicate.

It is also important to deploy and start each module depending on its type (as commented by @Carlitos Way):

• WARs are necessarily deployed to a servlet container (Tomcat, for example).
• JARs can be started from the command-line with a shell script.

Start an application which listens to a port

Each one of the non-web modules should have a main class which will be in charge of receiving the required arguments from the command line (at least the port number) and start the listening class - whatever it is.

package module.cmd;

public class MyMainClass
{
    public static void main(String[] arguments)
    {
        int port=Integer.parseInt(argument[0]);
        new MyListener(port).start();
    }
}

To run it, it would be enough to execute:

mvn exec:java -Dexec.mainClass="module.cmd.MyMainClass" -Dexec.args="8001"