If new devices are integrated into the system, only the small device driver has to be rewritten, and all functionality from both the bus driver and the class driver are inherited automatically. While all values from the slow control system can be accessed though the Web interface, they are in addition stored in a history system. This is a fast disk based database, which can be used to produce trend lines of slow control variables, as shown in the following figure. If experiments are controlled from remote places though the Web, it is desirable to have some means of communication between the collaboration members. For this purpose, an electronic logbook has been developed.
Users can enter and read information through the Web.
In addition to normal text, attachments can be entered like with E-mail. The logbook database can be searched for entries based on author, date or type. Following figure shows a logbook entry with an attached PAW image. Therefore, a Web interface for PAW has been written which remotely controls PAW and displays its output as a GIF image thourgh the web. This system has a separate homepage .