Note that since Java 6, the scripting API is in the standard Java library - see the documentation of the package
javax.script. The API in
See Java Scripting Programmer's Guide
The front page there mentions some reasons you might want to use scripting:
- Application extension/customization: You can "externalize" parts of your application - like configuration scripts, business logic/rules and math expressions for financial applications.
- "Command line" shells for applications -for debugging, runtime/deploy time configuration etc. Most applications have a web-based GUI configuaration tool these days. But sysadmins/deployers frequently prefer command line tools. Instead of inventing ad-hoc scripting language for that purpose, a "standard" scripting language can be used.
An example: You can script Oracle Weblogic using Python scripts, for example to configure your application server domain, to start or stop the server and to do other administration tasks.