Getting Started, Part 2

This document is part 2 of a tutorial. Part 1 is here.

We will increase the capability and internal quality of our application, incorporating templates, a database, better organization, and tests. We will try to make these adjustments gradually, to avoid losing our way.

Step 1 - Extract to Separate Class

Let us start with extracting our code out to its own file.

In the Main class, there is a section of code with the comment // Register some endpoints. We will cut that code, and paste it into a new spot. Create a new file at src/main/java/org/example/myproject/Endpoints.java, with the following content:

package org.example.myproject;

import com.renomad.minum.web.FullSystem;
import com.renomad.minum.web.RequestLine;
import com.renomad.minum.web.Response;

public class Endpoints {

    private final FullSystem fullSystem;

    public Endpoints(FullSystem fullSystem) {
        this.fullSystem = fullSystem;
    }
    
    public void registerEndpoints() {
        fullSystem.getWebFramework().registerPath(
                RequestLine.Method.GET,
                "",
                request -> Response.htmlOk("<p>Hi there world!</p>"));
    }
}

With that done, revise the Main class at src/main/java/org/example/myproject/Main.java to look like this:

package org.example.myproject;

import com.renomad.minum.web.*;
                                                                                                                       
public class Main {

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

        new Endpoints(fs).registerEndpoints();

        fs.block();
    }
}

Go ahead and run the application:

mvn compile exec:java

It should compile and run successfully, and you should be able to see it in the browser at http://localhost:8080/

When you are done running the application, stop it: control + c

Step 2 - Commit Our Work

We should make use of a source control tool, like Git, to keep track of our work.

Create a file in the root directory of playground, called .gitignore, to specify which files should not be recorded:

# ignore Intellij's configurations, if you need to
.idea/
# ignore Maven's build directory, as it gets rebuilt during compilation
target/

# the database directory
db/

# a file that is created when the system is running, and deleted
# when the system has stopped
SYSTEM_RUNNING

Now we can initialize a repo and commit our work.

git init
git status
git add .
git commit -m "initial commit"
git status

Here is what it looks like on my terminal:

$ git init
Initialized empty Git repository

$ git status
On branch master

No commits yet

Untracked files:
  (use "git add <file>..." to include in what will be committed)
        .gitignore
        pom.xml
        src/

nothing added to commit but untracked files present (use "git add" to track)

$ git add .

$ git commit -m "initial commit"
[master (root-commit) bd7a6e0] initial commit
 4 files changed, 76 insertions(+)
 create mode 100755 .gitignore
 create mode 100644 pom.xml
 create mode 100755 src/main/java/org/example/myproject/Endpoints.java
 create mode 100644 src/main/java/org/example/myproject/Main.java

$ git status
On branch master
nothing to commit, working tree clean

Next steps

The upcoming step is a doozy. We are going to write an integration test that will give us confidence in system behavior. This one test will assert correctness from end-to-end, which gives it the name, "end-to-end test". We will use some of the more advanced functions of the framework, but do not worry, the advanced parts are few, and I will explain as we go through. I will explain all that in part three of getting started