Evolution Hosting J2EE FAQ
J2EE FAQ Overview
This FAQ answers common questions related to working with J2EE applications
hosted by Evolution Hosting.Please feel free to contact support with any questions or suggestions.
J2EE FAQ Contents
- J2EE FAQ Overview
- J2EE FAQ Contents
- What is a J2EE module?
- Which J2EE modules does Evolution Hosting support?
- What is an EAR?
- What are WARs, or web applications?
- What is a default web application, or 'default-web-app'?
- What are Enterprise JavaBeans (EJBs)?
- Why EJB?
- What types of EJBs does Evolution Hosting support?
- Does Evolution Hosting support the Java Messaging Service (JMS)?
- How do I deploy EARs, EJBs, and WARS in Evolution Hosting?
- When deploying an EAR, do I also have to deploy its EJBs and WARs separately?
- What EJB containers can I choose from?
What is a J2EE module?
J2EE modules are components that may be individually or collectively (by way of an EAR)
deployed into a J2EE Server. They include: EARs (.ear), EJBs (ejb-jar), RARs (.rar), and
WARs (.war).
Which J2EE modules does Evolution Hosting support?
Evolution Hosting supports all J2EE modules except RARs (.rar, or Resource Adaptor Archive). For more information on how
to deploy Evolution Hosting supported J2EE modules, see How do I deploy EARs, EJBs, and WARS in Evolution Hosting?
What is an EAR?
EAR stands for "Enterprise Application Archive". EARs are a J2EE module that represents a
standalone application containing other J2EE modules such as EJBs, and web applications
(.war files). EARs were introduced in the J2EE specification as a way to package all
required files for an application into a single archive.
What are WARs, or web applications?
A WAR is a J2EE module that is a standalone web application that can be deployed to a Web
Container that supports the JSP 1.1/Servlet 2.2 specifications. WARs contain JSPs,
Servlets, supporting class files, and static content such as html. A web.xml descriptor is
used to define how the Web Container should deploy the web application. It may include
server-specific information, which is configured declaratively, eliminating the need to
hard-code information in your application.
What is a default web application, or 'default-web-app'?
Web Containers and full J2EE Servers generally provide a 'default-web-app', which allows you
to deploy individual JSPs, servlets, and static content without pre-packaging it into your
own web application. You may modify the default-web-app's existing web.xml file to include
registrations of your own components as needed.
What are Enterprise JavaBeans (EJBs)?
Enterprise JavaBeans (EJB) is a powerful component model for server-based applications as defined
by Sun's reference. This framework provides the basis for component based, multi-tier applications
that benefit from the "Write Once, Run Anywhere"tm capability inherent in all Java-based
programs. EJBs provide server-side functionality while separating the presentation layer from the
business layer, simplifying application development, and speeding deployment.
Why EJB?
EJBs are transactional and scalable. They are perfect for applications that need transactional
access to persistent information stored in databases such as customer and order data.
The transactional quality of EJBs prevents the loss of important data such as ecommerce orders, and the
highly scalable nature of EJB allows your web application to support high volume conditions.
What types of EJBs does Evolution Hosting support?
Evolution Hosting's support for EJBs is an extension of its supported J2EE servers such as Orion
Server and WebLogic Server 5.1. For instance, Orion Server currently supports
container-managed and bean-managed entity beans, stateless and stateful session beans, and
the new EJB 2.0 message-driven bean. WebLogic Server 5.1 currently supports only
container-managed entity beans, bean-managed entity beans, and stateless and stateful
session beans. Message-driven beans are only available in WebLogic Server 6.0 (not
supported by Evolution Hosting).
Does Evolution Hosting support the Java Messaging Service (JMS)?
Yes, if you have chosen to host your application with a J2EE server, you will have JMS
support. However, if you host just JSPs and servlets in a Web Container such as Apache
Tomcat, you will not have this feature available.
How do I deploy EARs, EJBs, and WARS in Evolution Hosting?
Evolution Hosting provides the ability to deploy and undeploy WAR files, and for those accounts that have
an EJB server, EJB-Jar files. This ability is build Evolution Hosting via the browser-based Evolution Hosting Console.
Once a Jar file has been uploaded, Evolution Hosting does the rest! We dynamically figure-out where to deploy
the Jar and register it for you in your server. If your account's EJB server supports "hot" deploy,
you do not even have to shut your EJB server down to deploy new Jars
When deploying an EAR, do I also have to deploy its EJBs and WARs separately?
No. Evolution Hosting's Smart Deployment technology figures out how to deploy each J2EE module
contained within the .ear file for you. We recommend deploying EARs over individual EJBs
and WARs since the deployment process for all contained components is taken care of for you
by Evolution Hosting. A single step to deploy multiple modules is much easier than deploying each
module individually!
What EJB containers can I choose from?
The Evolution Hosting Console supports the Orion Server,
the BEA WebLogic Server, and the
Oracle 9iAS Server EJB Containers.
Evolution Hosting can also host application servers not currently
integrated in the Console; inquire here.
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