• Developing a distributed environment requires the use of middle tier software (servers), there are several available on the market today from the market leading WebLogic a Web Sphere Application Server to open source projects such as JBOSS.
  • EJB Servers all conform to a standard specification of EJB 1.1 or EJB 2.0, with this compliance the movement from one server to another requires no or very few changes, if any changes are required it will be in the deployment descriptor file.
  • To give the solution the required scalability that would cater for large organizations the use of EJB servers will be required. Keeping with a 2 tier model will severely limit the options in the future, if a move over to a n-tier architecture is required a re-write of the software would be required.
  • By allowing for n-tier architecture from the beginning flexibility of deployment becomes inherent in the application, an approach of lowest common denominator needs to be taken to allow for this, a 2-tier architecture provides to high an abstraction to prove either flexible or scalable in the deployment.
  • For the initial development a tool such as Web Sphere Application Server should be used, this is an industry leader in the EJB Application Server arena, providing all the required capabilities for medium to large-scale deployments.
  • In addition to Web Sphere application Server a second and parallel distribution on an open source EJB server should be kept, this will ensure that all contingencies are taken into account to cater for the deployment options. For this second option JBOSS would be the EJB Server of choice, it is currently the most feature rich deployment available from the open source community
  • Generally Servers that support the distributed environment will also function as WEB and JSP Servers, if not out of the box then with an available add in. Using an application server to control all three of the environments needs to be assessed on a case-by-case basis as this may seem a logical step but the more specialized servers may well have capabilities not available in a complete package solution.