Running Applications

Running a SeedStack application is done by using the SeedMain class as entry point. This main class searches for a launcher on the classpath and delegates the startup and shutdown logic to it. A launcher is a class implementing SeedLauncher.

SeedStack provides two built-in launchers:

• In the seed-cli module, for command-line applications.
• In the seed-web-undertow, for Web applications embedding their own server.

Startup

Plain command-line

A standalone application is run from the command-line using the SeedMain class:

java [jvm-args] -cp ... org.seedstack.seed.core.SeedMain [app-args]

Capsule

One difficulty of running a Java application from the command line is to properly set its classpath. To simplify this task, SeedStack provides the ability to package any project in a Capsule, which is a sophisticated one-JAR packager and launcher. With a Capsule, launching the application becomes as simple as:

java [jvm-args] -jar app-capsule.jar [app-args]

Maven run goal

In development, you have the ability to run a standalone application directly from Maven with the run goal of the SeedStack Maven plugin:

mvn [-Dargs="app-args"] seedstack:run

This will automatically build the classpath from the project dependencies and create an isolated classloader to run the application.

Shutdown

To shutdown a standalone application, you simply have to gracefully stop the JVM. You can do this on any operating system this by hitting CTRL+C if the JVM is a foreground process. You can also do this on UNIX systems if the JVM is a background process by issuing a SIGINT signal to the JVM process:

kill -2 pid

Before the JVM stops, the shutdown logic of the SeedStack application will be invoked.

Tool mode

A SeedStack application can be run in tool mode. In this case a special launcher is invoked and will execute the specified tool. You can run any module in tool mode by specifying the seedstack.tool system property:

java [jvm-args] -Dseedstack.tool=toolName -cp ... org.seedstack.seed.core.SeedMain [tool-args]

or with a Capsule:

java [jvm-args] -Dseedstack.tool=toolName -jar app-capsule.jar [tool-args]

Lifecycle listener

You can implement the LifecycleListener interface to be notified about the application lifecycle events:

public class MyLifecycleListener implements LifecycleListener {
    @Logging
    private Logger logger;

    @Override
    public void started() {
        logger.info("Application has been started");
    }

    @Override
    public void stopping() {
        logger.info("Application is about to be stopped");
    }
}

Such classes are injectable and can be used to implement initialization and shutdown logic.