As announced, not every change in Franca 0.9.0 could be implemented in a backward-compatible way. Most of those changes will affect developers of generators and transformations, some might also affect designers of Franca interfaces. In order to help you with the migration from 0.8.x, a 
Migration Guide is available.
The documentation is not yet updated to the features of this new release. See below a list of new features in 0.9.0, please refer to the corresponding issues in the Franca issue tracker for details. 
New with version 0.9.0
Some changes in 0.9.0 might require updates of Franca model files, marked with an asterisk below.
- IDL: provide range-based integer types (issue 18)
- IDL: allow definition of constants including complex initializer expressions (issue 74)
- IDL: replace string constants in enumerations by integer numbers. Using strings is still possible, but deprecated (issue 52, issue 87)
- IDL: improve action language for contracts (issue 55)
- * IDL: add new validation restrictions, esp. for structs and unions (issue 70) and enums (issue 89)
- * IDL: prohibit fully qualified names for typeCollections and interfaces (issue 73)
- API: changed type of various flags to boolean, previously type was nullable string (issue 21)
- Tools: new model converter tool for handling range-based integer types (issue 18)
- Tools: new generation of PropertyAccessors also for type collections (issue 66)
- Tools: updated wizards for creating new Franca IDL and deployment files (issue 91)
- Tools: code generator for HTML5/JS is now part of the release (issue 82)
- Tools: the contract validation engine is now part of the release (issue 25)
- Tools: the DLT viewer plug-in is based on this release, see Franca-DLT on github (issue 65)
- D-Bus: improvements for Franca=>D-Bus transformation (issue 80)
- D-Bus: a new external validator for checking incompatibilities with plain D-Bus (issue 71, issue 84)
- D-Bus: the D-Bus model generated by transformation from Franca contains back-links to the Franca model (issue 69)
- new reference models for Franca IDL, see org.franca.examples.reference (issue 76)
- reduce dependencies of Franca plug-ins, esp. to JDT (issue 91, issue 88)
- a Franca RCP product is now built for various platforms (issue 79)
- the feature structure of the Franca update site is now more fine-grain (issue 78)