Application servers are middleware software solutions available from different vendors. The J2EE platform has brought in standardization and compatibility across several competing products in the market. Currently, many companies are offering J2EE-certified application server products.
There are several featuressuch as scaling, load balancing, security, and administrationthat should be considered when selecting a particular product for the enterprise. More than the quality of a particular feature, it is the relevance and importance of it to the given enterprise computing environment that should dictate the choice.