Abstract:
The need for a mechanism to control and filter subscriptions to control system variables by the client was described in a paper at the ICALEPCS2009 conference [1]. The implementation follows a plug-in design that allows the insertion of plug-in instances into the event stream on the server side. The client can instantiate and configure these plug-ins when opening a subscription, by adding modifiers to the channel name using JSON notation [2]. This paper describes the design and implementation of a modular server-side plug-in framework for Channel Access, and shows examples for plug-ins as well as their use within an EPICS control system.