In the paper a particular approach to transaction management in databases supporting collaborative applications is proposed. It is based on a new transaction model which allows practically unrestricted collaboration among members of the same team. The basic assumption of this model is that collaborating users try to solve their access conflicts on a higher level than the level of a database management system. Users are not mutually isolated, as it happens in classical databases. They can freely negotiate, presenting their intentions concerning future work. The proposed approach was verified in Agora prototype which is a Web-based conferencing system, offering conference participants a flexible tool for collaborative document writing. Agora is implemented on the top of Oracle RDBMS.