Use of modern software technology in the redesign of the OPAL trigger software

The OPAL experiment at LEP has a central trigger system which is modular and VME based. An upgrade of the control software was necessary to increase the flexibility and maintainability of the system. The software has been completely re-engineered in a project which lasted from January until August 1997. The use and benefits of a customised software development environment as an instrumentation of the design process, and of the project infrastructure, are described. The importance of this approach for the success of the project and its suitability for use in real-time systems is demonstrated.