JEE Core Concepts: Difference between revisions
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=Changing Application Behavior without Changing Code= | =Changing Application Behavior without Changing Code= | ||
The possibility to change an application's behavior without changing code is a core concern in JEE. The entire Chapter 5 in the JEE specifications is dedicated to it. The essential mechanism than makes this possible is the ''application component environment'', also known as ''enterprise naming context (ENC)'', and the fact that the application code ''uses named entries'' in ENC to refer to configuration values and external resources. The names of those elements do not change in the code, but during the deployment, those configuration values and external resource references are ''mapped'' to deployment environment specific actual values and actual resources. | The possibility to change an application's behavior without changing code is a core concern in JEE. The entire Chapter 5 in the [[JEE#jsr_316|JEE specifications]] is dedicated to it. The essential mechanism than makes this possible is the ''application component environment'', also known as ''enterprise naming context (ENC)'', and the fact that the application code ''uses named entries'' in ENC to refer to configuration values and external resources. The names of those elements do not change in the code, but during the deployment, those configuration values and external resource references are ''mapped'' to deployment environment specific actual values and actual resources. | ||
The key element here is the use of ''deployment descriptors'', that provide this mapping. | The key element here is the use of ''deployment descriptors'', that provide this mapping. | ||
Revision as of 02:05, 7 April 2017
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Changing Application Behavior without Changing Code
The possibility to change an application's behavior without changing code is a core concern in JEE. The entire Chapter 5 in the JEE specifications is dedicated to it. The essential mechanism than makes this possible is the application component environment, also known as enterprise naming context (ENC), and the fact that the application code uses named entries in ENC to refer to configuration values and external resources. The names of those elements do not change in the code, but during the deployment, those configuration values and external resource references are mapped to deployment environment specific actual values and actual resources.
The key element here is the use of deployment descriptors, that provide this mapping.