Application Servers | Deployment

What are Application Servers?

Application servers are software frameworks that provide an environment in which applications can run, regardless of what they are or what functions they perform. They serve as a middle layer between the database and the client, enabling the execution of business logic and data processing, as well as integrating various services and applications.

An application server supports the development and deployment of applications by providing various services such as transaction management, messaging, security, and resource pooling.

Key Features of Application Servers

Scalability: Application servers can handle increasing loads by distributing them across multiple server instances.
Transaction Management: They manage transactions to ensure data integrity, especially in enterprise applications.
Security: Provide authentication and authorization mechanisms to protect applications from unauthorized access.
Load Balancing: Distribute client requests across multiple servers to enhance performance and availability.
Integration: Facilitate integration with various data sources and services, such as databases and messaging systems.

Examples of Popular Application Servers

Some of the widely used application servers include:

Apache Tomcat: A popular open-source Java Servlet container that allows for running Java applications.
JBoss EAP: A subscription-based open-source application server from Red Hat that supports Java EE.
GlassFish: An open-source application server project for the Java EE platform.
WebLogic: An enterprise-level Java EE application server developed by Oracle Corporation.

Deploying Applications on an Application Server

Deploying applications on an application server generally involves packaging the application into a deployable format (e.g., WAR or EAR file) and then uploading it to the server's deployment directory. Below is a simple example of deploying a Java web application on Apache Tomcat.

Example: Deploying a WAR File on Apache Tomcat

1. Package your Java web application into a WAR file.

2. Copy the WAR file to the Tomcat deployment directory (e.g., /path/to/tomcat/webapps/).

3. Start the Tomcat server.

4. Access your application at http://localhost:8080/yourapp.

Hibernate and Application Servers

Hibernate is an object-relational mapping (ORM) framework that simplifies database interactions in Java applications. When integrated with an application server, Hibernate can leverage the server's transaction management and connection pooling features, which enhances performance and reliability.

To configure Hibernate in an application server, you typically need to:

Set up a DataSource in the server configuration.
Configure Hibernate settings to use the DataSource.
Deploy your application, ensuring it has access to Hibernate libraries and configurations.

Example: Hibernate Configuration in a Java EE Application

In your persistence.xml file, you might include:

<persistence xmlns="http://xmlns.jcp.org/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence
             http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd"
             version="2.1">
    <persistence-unit name="myPersistenceUnit">
        <jta-data-source>jdbc/myDataSource</jta-data-source>
        <properties>
            <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect"/>
        </properties>
    </persistence-unit>
</persistence>

Conclusion

Application servers play a vital role in the deployment and management of applications, providing essential services that facilitate development and enhance performance. Integrating frameworks like Hibernate with application servers leverages their capabilities, leading to robust and scalable applications.

Application Servers Tutorial