Development of web-based applications needs tools in order to make the application development more effective by using/re-using business rules as well as web services. These tools should incorporate facilities for capturing different semantic aspects of an application. This paper presents a new conceptual and technological framework of using a rule language and rule engine for capturing semantics in modern web-based systems. The framework enables to cover two aspects of semantics in web-based systems: business rules and web service composition logic. The technology consists of 2 main parts: the application server Xstone for creating 3-layered systems and the RqlGandalf rule solver. The middleware server Xstone connects to Oracle, PostgreSQL databases and the RqlGandalf rule system. The RqlGandalf rule system is targeted for two different tasks: defining and using business logic rules as well as for rule-based synthesis of complex queries over web services. The presented rule-based system development technology is implemented for the Linux platform as open source software.