Actions in Struts are POJO , is also considered as a Model. The role of Action are to execute business logic or delegate call to business logic by the means of action methods which is mapped to request and contains business data to be used by the view layer by means of setters and getters inside the Action class and finally helps the framework decide which result to render
Most of the trivial work are made easier to achieve for example automatic form population. Intelligent configuration and defaults for example you can have struts.xml or annotation based configuration and out of box interceptors can provide facilities that a common web application needs Now Struts2 can be used anywhere in desktop applications also, with minimal or no change of existing web application,since actions are now POJO.POJO actions are even easier to unit test.Thanks to interceptors Easier UI and validation in form of themes and well known DOJO framework. Highly plugable,Integrate other technologies like Spring,Hibernateetc at ease. Ready for next generation RESTFUL services
A ValueStack is a place where all the data related to action and the action itself is stored. OGNL is a mean through which the data in the ValueStack is manipulated.
struts.devMode is a key used in struts.properties file (Can also be configured in struts.xml file as