Java EE PaaS and Application Server Interoperability
Source: Srinivasan Sundara Rajan
Java EE PaaS Growth & Interoperability Concerns
As observed in my earlier articles, the Java EE PaaS portfolio is gaining in strength each day, with support from major players such as IBM, Oracle, VMWare, Redhat , Google and Amazon.
However unlike the Microsoft > .NET Framework > Azure PaaS equation where there is just one version of the framework from one vendor, the openness of Java EE led to several implementations of application server-specific implementations.
As Java EE standards define a core set of API, frame works and features as part of its implementation, an application server is the container that executes these instructions and provides a development and runtime platform for Java EE applications.
While application servers are expected to implement the Java EE specifications & technologies like (SERVLETS, JAVA SERVER FACES, ENTERPRISE JAVA BEANS, PERSISTENCE and others like WEB SERVICES) in exactly the same way , they do have implemented lot of extensions specific to the application servers to improve the scalability , usability and other
Quality of Service of the Applications
For example if you are developing your applications on WebLogic platform, Optionally, a weblogic.xml deployment descriptor, an XML document containing WebLogic Server-specific elements for Web applications can be used. Additional deployment descriptors provide WebLogic-specific deployment information. A weblogic-cmp-rdbms-jar.xml deployment descriptor unique to container-managed entity beans maps a bean to tables in a database. The weblogic-ejb-jar.xml deployment descriptor supplies additional information specific to the WebLogic Server environment, such as JNDI bind names, clustering, and cache configuration.
Similarly IBM WebSphere has many extensions beyond the base Java EE specifications, for example, WebSphere Application Server version 7.0 supports configuration of stateful session bean timeout, per bean, using the ibm-ejb-jar-ext.xmi file (for EJB 2.x modules), and the ibm-ejb-jar-ext.xml file (for EJB 3.x modules).
Over the last several years while Java EE has been the accepted as an enterprise standard in many a enterprises, however due to vendor preferences and marketing strategies most enterprises are yet tied to specific application server implementations like WebSphere, WebLogic and there is a huge penetration of open source application servers like JBOSS, Tomcat also prevalent added to this they are relatively smaller players like Pramati, SYBASE Application Server in the picture.
In spite of all the cross application server interoperability the Java EE platform brings in, yet enterprises do find significant effort in porting an application from one application server to another and especially they spent efforts on the non-functional characteristics like performance, scalability, availability and security.
With all the Application Server Specific interoperability concerns in the Java EE applications in mind, let us analyze the current Java EE PaaS market from that perspective.
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