Oracle Application Server - Basics

This post is for those people who are new to Application Server domain and need simple answers to basic questions i.e., a couple of What is ? kind of questions. Read on...

What is?

1. What is Application Server?

An application server is a software platform that delivers content to the Web. In our case, it is a layer between the clients and the database called middle tier. Common Application logic, business rules, etc are coded in applications in middle tier

2. What is OC4J Instance?

Oracle Containers for Java EE (OC4J) is the core Java EE runtime component of Oracle Application Server.It is a program that serves the J2EE requests of the clients. An OC4J instance is the copy of 1 such program.

3. What is (Middle tier) Application?

The packaged code deployed on the middle tier which contains common application logic, business rules, etc is a Middle tier Application.

4. What is Data Source?

Object to connect to a database. A data source is a Java object and offers a portable, vendor-independent method for creating connections to databases. A data source object's properties are set so that it represents a particular database. An application can use a different database by changing the data source's properties; no change in the application code is required.
The data sources for the OC4J instance are referenced as Java Naming and Directory Interface (JNDI) locations.

5. What is Connection Pooling?

A Data Source (Managed) uses Connection pool to efficiently manage connections. OC4J provides the connection pool feature to increase efficiency by maintaining a cache of physical connections that can be reused. When a client closes a connection, the connection gets placed back into the pool so that another client can use it. A connection pool improves performance and scalability by allowing multiple clients to share a small number of physical connections.

6. What is Deployment?

In Simple terms, Deployment means installing the application. When you deploy application, the Application Server will unpack the deployment file (EAR/WAR/JAR/RAR) and create the directory structures with files, just like they were packed by the developer.

7. What is RMI Port?

Remote Method Invocation (RMI) is a technology that allows an object running in one Java virtual machine (JVM) to invoke methods on an object running in a different Java virtual machine (JVM).

The complete Application Server documentation is available here:

http://download.oracle.com/docs/cd/B31017_01/index.htm

Best Luck :)