With the advent of new distributed applications like online auctions and e-commerce, the reliability requirements are becoming tighter and tighter. These applications require a combination of data consistency, robustness, high availability and performance. However, there is no single mechanism providing these features. Data consistency is preserved using transactions. Robustness can be obtained by foreseeing and handling exceptions. Objects groups can help in increasing the availability and performance of an application. In order to attain the growing demand of higher levels of reliability it is necessary to integrate these mechanisms with a consistent semantics. This article addresses this topic and studies the role of exceptions in this context.