Computer scientists working in medical informatics have to face the problem that software offered by industry is more and more adopted for clinical use by medical professionals. A new challenge arises of how to combine commercial solutions with typical medical software that already exists for some years and proved to be reliable with these off-the-shelf solutions [1]. With the HERMES project, this new challenge was accepted and possible solutions to integrate existing legacy systems with state-of-the-art commercial solutions have been investigated. After a period of prototyping to assess possible alternative solutions, a system based on an indirect client-server model was implemented with help of the industry. In this paper, its architecture is described together with the most important features currently covered. Based on the HERMES architecture, both systems for clinical data analysis and patient care (cardiology) are currently developed.