quick_start.md

Quick Start

This software will enable you to create web applications in Java. It provides the bare minimum of what is necessary for that task, plainly and simply.

Step 1 - Java

Try this in your shell:

javac -version

The result should be javac 21 or higher. If it not, check out Step-by-step guide to installing Java on Windows or Java on Mac

After changing environment variables, you must close and reopen your terminal to see the change

Make sure to have the JAVA_HOME environment variable set. Test like this:

echo $JAVA_HOME

The output should be the directory where Java is installed, but not the bin directory where java and javac live. Try this (this command changes directory to JAVA_HOME and then lists the files there):

cd $JAVA_HOME
ls

You should see results like: bin conf include jmods legal lib release

This is why your PATH environment variable should include something like this:

$JAVA_HOME/bin

Step 2 - download the "small" example

Next, we will download a project that includes the simplest-possible web application. Grab this project.

https://github.com/byronka/minum_usage_example_smaller

Step 3 - run the example

Run this command in its directory:

./mvnw compile exec:java

It will compile and you will be able to view it at http://localhost:8080

Step 4 - modify the example

Hit Main.java and take a moment to review. Try some of the following recommended changes. To see your changes, cancel the running program by pressing ctrl+c and run ./mvnw compile exec:java to start it again.

For ease of reference, here is the code you will see:

public class Main {

    public static void main(String[] args) {
        // Start the system
        FullSystem fs = FullSystem.initialize();

        // Register some endpoints
        fs.getWebFramework().registerPath(
                StartLine.Method.GET,
                "",
                request -> Response.htmlOk("<p>Hi there world!</p>"));

        fs.block();
    }
}

• Add a new path - have it serve content from /hello
• (After making this change, stop the running server with ctrl+c and rerun ./mvnw compile exec:java)

public class Main {

    public static void main(String[] args) {
        // Start the system
        FullSystem fs = FullSystem.initialize();

        // Register some endpoints
        fs.getWebFramework().registerPath(
                StartLine.Method.GET,
                "",
                request -> Response.htmlOk("<p>Hi there world!</p>"));
        fs.getWebFramework().registerPath(
                StartLine.Method.GET,
                "hello",
                request -> Response.htmlOk("<p>Hi there world!</p>"));

        fs.block();
    }
}

• Adjust to say hello to a query string parameter. (After making this change, stop the running server with ctrl+c and rerun ./mvnw compile exec:java)

public class Main {

    public static void main(String[] args) {
        // Start the system
        FullSystem fs = FullSystem.initialize();

        // Register some endpoints
        fs.getWebFramework().registerPath(
                StartLine.Method.GET,
                "",
                request -> Response.htmlOk("<p>Hi there world!</p>"));
        fs.getWebFramework().registerPath(
                StartLine.Method.GET,
                "hello",
                request -> {
                    String name = request.requestLine().queryString().get("name");
                    return Response.htmlOk(String.format("<p>Hi there %s!</p>", name));
                });

        fs.block();
    }
}

Press ctrl+c to stop the running server.

Next steps

Now you are ready to go further. If you want a step-by-step tutorial on building a project with Minum from the ground up, check out the getting started tutorial.

Or, you may want to pore through a larger example

Have fun!