Java EE PaaS and Application Servers
The Java Enterprise Edition Platform As A Service is a correct and first direction in enabling enterprises to truly concentrate on the business agility provided by Java EE platform and not get bogged down by the version, compatibility and other issues typical of the platform. However the current Java EE PaaS eco system tied very much to the specific application server implementations, while they are trying their best to bring in the much needed open platform characteristics.

Innovation In Java EE PaaS and Waratek Platform
Waratek (Waratek.com) has recently come up with Java EE PaaS platform and the product is termed as Cloud VM For Java. The Waratek Cloud VM for Java provides the platform for cloud computing that lets you migrate existing applications effortlessly and seamlessly.

As explained in the above sections of Java PaaS implementations from various vendors, while all of them are good for new development due to the application server centric capabilities there will be challenges for enterprises in moving the existing applications. Rather than re-write or significantly re-engineer Java applications to reap the benefits of the Cloud, use Waratek Cloud VM for Java to painlessly port them over. This enables existing Java investments and subsequent Java solutions to thrive on a more flexible platform with key cloud characteristics, such as multi tenancy, granular elasticity, instant scalability, prioritization and real time metering.

Architecture Of Waratek Platform:

• Waratek, the Cloud VM for Java, uses Java Virtual Containers (JVCs)
• A single JVM can host tens or hundreds of JVCs: from 1MB up to many GBs
• Every .war/.ear app gets its own JVC
• Any standard Java application can run on the Waratek VM with no alteration required
• This interoperability is mainly achieved through a layer called, ‘Waratek Platform Extender'
• The Platform Extender layer operates as an extension to the JVM to facilitate tailored multitenancy for different application frameworks
• The default Tomcat Platform Extender for the Apache Tomcat Servlet Container.
• Multiple Platform Extenders are available for optimised multitenancy with leading application server suites such as JBoss, WebLogic, etc. The Platform Extenders complement existing application server suites, by decoupling a virtualized tentant application from the hosting application server suite on which it runs.
• Each Java VC presents a virtualized abstraction to the hosted application of the underlying JVM and application server platform (if any), and appears invisible to the hosted application software within
• The below diagram from the courtesy of Vendor , explains the basic architecture of the Waratek Platform

Summary
The primary aim of PaaS is to relieve the enterprises from the complexities of the platform and provide them path to concentrate on business needs, in that context huge investment on porting existing applications to a PaaS platform may not be acceptable from budget and cost allocation perspective. Innovations like Waratek platform are trying to solve this problem. After all Java comes with a concept of "Write Once and Run Any Where" and it is only appropriate for the Java PaaS platform in support of the concept. We will see more products and further offerings in this space to the betterment of enterprises.

• Sun Introduces the Next Major Version of the Open Source Java EE 5 (GlassFish V2) Application Server
• PaaS: .NET vs Java EE
• Sun Announces Two Million Solaris 10 Licenses Distributed; Includes Open Source Application Server with Solaris to Further Accelerate Adoption