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OASIS, the Open Analogue Signal Information System, was fully deployed in 2006 and now allows observation of more than 1900 analogue signals in the CERN accelerator complex. Our first operational experience in 2005 indicated that, for performance reasons, a change in the technology used to access the database was needed. Further experience throughout 2006 showed that an even bigger move was required in order to keep the system easy to maintain and improve. Initially based on the J2EE Enterprise Java Beans (EJB) and Java Messaging Service (JMS), the OASIS server was tightly coupled to OC4J, the Oracle’s EJB container, and SonicMQ, a JMS broker. The upgrade to the latest version of these products being unnecessary complex and the architectural constrains being major drawbacks of the EJBs, it was decided to move completely away from those. The paper presents the new server architecture based on open-source products – Spring, ActiveMQ & Hibernate. It also presents the improvements done to the user request processing in order to reduce drastically the response time. Finally, the concept of Virtual Signal is introduced along with the new scalability constraint it brings into the system.
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