DISTRIBUTED ENVIRONMENT
- 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.
http://www.bea.com/products/weblogic/server/index.shtml
http://jakarta.apache.org/tomcat/index.html
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