Unified Expression Language in Java Server Faces(JSF)

One of these is the UI component framework, JavaServer Faces technology. To support its powerful features, this framework needed its own expression language (EL). However, this EL presented some problems when used with some JSP tags. Therefore, the specification writers and expert groups of the Java webtier technologies collaborated on a new, unified expression language to help align these technologies by adopting the features offered by the JavaServer Faces expression language. These features include the ability to use expressions to set the value of external object properties as well as get data from them and to invoke methods. At the same time, the webtier team made the language pluggable and extensible so that advanced developers can add custom resolvers able to evaluate expressions not already supported by the expression language.read full article