One of the main features that makes Web services a promising technology for automating B2B interactions is the ability to dynamically combine a set of services into a new value added composite Web services (CS). However, a main problem that remains is how to ensure a correct and reliable execution. This paper presents a set of techniques to improve CS transactional behavior for a better failures handling. Basically, we propose a set of mining techniques to discover CS model and its transactional behavior from logs. Then, based on this mining step, we use a set of rules to improve its design. We refer to this set of techniques as the Business Process Intelligence (BPI) techniques suite.