Epics version 4 progress report

EPICS Version 4 is the next major revision of the Experimental Physics and Industrial Control System, a widely used software framework for controls in large facilities, accelerators and telescopes. The primary goal of Version 4 is to improve support for scientific applications by augmenting the control-centered EPICS Version 3 with an architecture that allows building scientific services on top of it. Version 4 provides a new standardized wire protocol, support of structured types, and parametrized queries. The long-term plans also include a revision of the IOC core layer. The first set of services like directory, archive retrieval, and save set services aim to improve the current EPICS architecture and enable interoperability. The first services and applications are now being deployed in running facilities. We present the current status of EPICS V4, the interoperation of EPICS V3 and V4, and how to create services such as accelerator modelling, large database access, etc. These enable operators and physicists to write thin and powerful clients to support commissioning, beam studies and operations, and opens up the possibility of sharing applications between different facilities.