Step Snap 1: [Metabase- Understanding JAR Execution Principles 🚀]

Here, just a optional route here, but it’s still fun to know! You see the installation methods for Metabase are two ways. First way is the docker which is considered most common in our use case and we have deat with a lot earlier. However, what is this JAR? So, let’s dive into it.

1. The Nature of JAR Files

• JAR (Java Archive) is a compressed package format that contains all necessary class files (.class), resource files, and library dependencies
• It acts as a self-contained application package with a complete runtime environment
• Includes a MANIFEST.MF file that specifies the entry class (main class) and other configuration settings

1. Runtime Mechanism

• When you execute java -jar metabase.jar:
  • JVM reads MANIFEST.MF to locate the entry class
  • Loads all internally packaged dependencies
  • Launches the built-in web server (like Jetty)
  • Initializes the application

1. Comparison with Python + Flask

Python + Flask Package  |        Java JAR
------------------------|-------------------------
app.py                  |    Main.class
requirements.txt        |    Built-in dependencies
virtualenv              |    JVM runtime environment
Flask dev server        |    Built-in web server

Indeed, it's somewhat similar to packaging a Python Flask application, but there are several key differences:

1. Dependency Management

• Python: Requires pip to install dependencies
• JAR: All dependencies are pre-packaged internally

1. Runtime Environment

• Python: Requires Python interpreter + virtual environment
• Java: Only needs JVM, more independent

1. Deployment Convenience

• JAR files are completely self-contained, requiring only Java environment to run