---
title: "Overview"
url: https://docs.catalyst.zoho.com/en/serverless/help/appsail/help-guides/java/overview/
description: "Catalyst AppSail is a fully-managed PaaS component of Catalyst Serverless that enables you to develop and deploy services in Java, Node.js, and Python in the cloud with ease, and manage your platform instances."
last_updated: 2023-09-04T11:41:45Z
service: Serverless
type: general
---

# Java

### Overview

The Java programming environment includes a variety of frameworks that contain pre-written classes, templates, packages, and structure upon which you can build your own code. As mentioned earlier, Catalyst enables you to [initialize](https://docs.catalyst.zoho.com/en/cli/v1/initialize-resources/initialize-appsail/) or [add](https://docs.catalyst.zoho.com/en/cli/v1/add-appsail/) an AppSail service in one of these two formats:

* [Java- WAR](https://docs.oracle.com/cd/E19199-01/816-6774-10/a_war.html)
* [Java- SE](https://www.oracle.com/cis/java/technologies/java-se-glance.html)
 
After you select the Java stack while initializing an app service, you can select one of these options.  However, you can still build your Java application with any frameworks; incorporate any libraries, modules, or dependencies; generate it as any standard package; and follow any editions you require.

> **Note:** When you use the Java WAR template for deploying your Java application exported as a WAR file, you need not embed a Java web server in your application, as AppSail will bundle your application with a server by default. If you choose Java SE as your template for all other Java application formats, such as a JAR file, you will need to include an embedded server in your application.

The Java help guide contains step-by-step instructions on building basic sample apps with some of the most popular frameworks, using popular Java web servers in them, and deploying these apps as AppSail services, and configuring [startup commands](https://docs.catalyst.zoho.com/en/serverless/help/appsail/key-concepts/appsail-execution/#startup-commands) as required.

### Prerequisites

Depending on the framework, server, and edition you use in these examples, you will need to ensure that you have all the prerequisites installed in your local machine.