The Spring Expression language is now the default implementation used in Spring Web Flow. Existing applications can still choose to plug in the Unified EL or OGNL if they wish to do so. Spring EL however is the recommended approach. It offers advantages such as close integration with the Spring 3 Type Conversion and Formatting system and is also used in other Spring projects. For more information see Chapter 4, Expression Language (EL).

Spring Web Flow now uses the new Spring 3 type conversion and formatting mechanism that includes use of formatting annotations such as NumberFormat and DateTimeFormat. The Spring 3 type conversion was influenced by the existing mechanism used in Spring Web Flow. Hence Web Flow users should find this to be a logical step forward.

Existing applications can continue to use the custom converters they currently have. With the new approach however, they can now use a single mechanism across Spring MVC controllers and flow definitions. For more information see Section 5.7, “Performing type conversion”.