Using Nuts Application Framework (NAF)

Using nuts is transparent as we have seen so far. It is transparent both at build time and runtime. However, nuts can provide our application a set of unique helpful features, such as install and uninstall hooks, comprehensive command line support and so on.

To create your first NAF application, you will need to add nuts as a dependency and change your pom.xml as follows:

<?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.mycompany.app</groupId>
    <artifactId>my-app</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>jar</packaging>
    <dependencies>
        <dependency>
            <groupId>net.thevpc.nuts</groupId>
            <artifactId>nuts</artifactId>
            <version>0.8.4</version>
        </dependency>
        <dependency>
            <groupId>jexcelapi</groupId>
            <artifactId>jxl</artifactId>
            <version>2.4.2</version>
        </dependency>
    </dependencies>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
        <nuts.application>true</nuts.application>
    </properties>
</project> 

Please take note that we have added a property nuts.application=true. Actually this is not mandatory, but this will help nuts package manager detect that this application uses NAF before downloading its jar (the information will be available in the pom.xml descriptor on the remote repository).

Then we will add some cool features to our application. We write a dummy message whenever the application is installed, uninstalled or updated. We will also add support to "--file=[path]" argument to specify the workbook path.

package com.mycompany.app;

import java.io.File;

import jxl.Workbook;
import jxl.write.WritableWorkbook;

public class App implements NApplication {

    public static void main(String[] args) {
        // just create an instance and call runAndExit in the main method
        // this method ensures that exist code is well propagted
        // from exceptions to caller processes
        new App().runAndExit(args);
    }

    @Override
    public void run(NSession session) {
        NCmdLine cmd = session.getAppCmdLine();
        File file = new File("file.xls");
        while (cmd.hasNext()) {
            switch (cmd.getKey().getString()) {
                case "--file": {
                    NArg a = cmd.nextEntry().get();
                    file = new File(a.getStringValue());
                    break;
                }
                case "--fill": {
                    // process other options here ...
                    break;
                }
                default: {
                    s.configureLast(cmd);
                }
            }
        }
        try {
            WritableWorkbook w = Workbook.createWorkbook(file);
            s.out().printf("Workbook just created at %s%n", file);
        } catch (Exception ex) {
            ex.printStackTrace(s.err());
        }
    }

    @Override // this method is not required, implement when needed
    public void onInstallApplication(NSession s) {
        s.out().printf("we are installing My Application : %s%n", s.getAppId());
    }

    @Override // this method is not required, implement when needed
    public void onUninstallApplication(NSession s) {
        s.out().printf("we are uninstalling My Application : %s%n", s.getAppId());
    }

    @Override // this method is not required, implement when needed
    public void onUpdateApplication(NSession s) {
        s.out().printf("we are updating My Application : %s%n", s.getAppId());
    }
}

Now we can install or uninstall the application and see the expected messages.

nuts -y install com.mycompany.app:my-app
nuts -y uninstall com.mycompany.app:my-app