1. CMW CORBA-based Controls Middleware at CERN
CMW team, CERN
Kris Kostro, Nikolai Trofimov, Steen Jensen, Jens Andersson, Francesco Calderini, Vito Baggiolini, Francois Chevrier, Slawek Maludzinski

2. Layout CMW motivation Architecture Remote Device Access (RDA)
CMW servers and clients
Administration services
Naming and configuration services
Current status
Experience

3. Motivation for the new middleware
Support for OO programming, in particular Java.
Support for publish/subscribe paradigm and event-driven programming
Support for industrial standards in controls (OPC, SCADA, Windows)
New middleware for the LHC era

4. CMW Architecture Clients Servers CMW Infrastructure RDA, CORBA, JMS
User written
Middleware
Existing or off-shelf
Java Control
Programs
RAD programs
(VB, Excel)
C++ programs
Clients
Middleware Client API
Device/Property Model Topic Model
Naming
Service
CMW Infrastructure
RDA, CORBA, JMS
Configu-
ration
Service
Server Framework API (C++, Java)
Servers
Virtual Devices
(Java, C++)
New
Servers
SL-Equip
Server
PS-GM
Server
OPC
Gateway
Physical Devices (RF, BT, BI, Powering)

5. Device Model
Control system consists of named devices (position monitor, beam line)
Devices are composed of properties (position, current)
Operations on properties set, get, subscribe, unsubscribe
Devices are organized into device classes

6. RDA Remote Device Access
RDA implements the device model
Properties are represented by name, the API is a narrow one
get() & set() operations implemented as blocking CORBA calls.
Subscription updates implemented as CORBA callbacks in user code.
Update operations implemented as one-way calls
Data objects similar to CDEV data

8. CMW servers
CMW servers are normally written in C++ and run on LynxOS VME front-ends
Windows servers for OPC, Linux for gateways
Server framework to support polling and synchronize with timing system
They are often generic servers configured from Oracle DB

9. CMW server framework

10. Server Example: SL-Equip
LynxOS Front-End
CMW Equip Server
Hardware
MIL1553 driver
RDA
CORBA
SFW
OPC Server
eqsrv Servers
Hardware
Server
Classes
Timing events
from network
SVMQ
Configuration from Database

11. Configuration from Database
Server Example: OPC
Windows (NT, 2000)
CMW OPC Server
Hardware
OPC server
RDA
CORBA
Server
Classes
Configuration from Database
Mapping between OPC items
And device/properties

12. CMW clients Java clients are the main category
C++ clients to connect to SCADA systems (PVSS driver)
C++ clients for legacy Motif applications
VB and Excel applications behind a Java or C++ front-end

14. Narrow API DeviceBase device = new DeviceBase("BPM1”);
cs = new DefaultCycleSelector("211e0101");
Data result = device.getData("Pos", cs);

15. System Administration
Administration facilities have been described as CORBA interface. All CMW servers implement this interface: RDA servers and also directory and database servers.

16. System Administration (cont.)

17. System Administration (cont.)
The CMW management console allows browsing the server namespace and displaying server state
The general state of the server (OK, BAD, WARNING) is requested periodically
More details about server as well as server and client statistics can be obtained through separate methods.
Servers can be shut-down or restarted remotely and log levels can be set.

19. Naming and configuration
Device names are resolved to server names via CORBA directory server connected to Oracle database
Server names are resolved to CORBA RDA DeviceServerBase objects via the OMG Naming Service (ORBacus Names)
Servers register their names with Naming Service on startup
Servers can auto configure via a CORBA database server (no Oracle for LynxOS)

20. Naming and configuration
CMW Directory
server (Java)
Java Control
Programs
Device name
resolution
Device access
JDBC
ORACLE
OMG
Naming
Service
CMW DB
server (Java)
Server configuration
from SQL query
Device Server
In Front-End
Physical Device
JDBC
ORACLE

21. CMW current state All CERN equipment can be accessed via CMW
Operational in PS since March 2002
Naming and configuration services are operational
Main use is in Java, C++ client recently developed
Currently working on consolidation and improvements (version 2.0)

22. Supported platforms Java C++ Server framework supported on:
Client and server API’s
Administration tools, CMW Explorer, directory and configuration servers are in Java
C++ Server framework supported on:
PowerPC LynxOS 3.1.0
Linux Intel
Windows 2000
C/C++ Client API on:
Linux

23. Actual CORBA implementations
In use
ORBacus OBE for C++
LynxOS 3.1.0
Linux (i686)
ORBacus JOB 3.3.4, JOB 4.0.4
Have also been used
OrbExpress
Omniorb (not in CMW)

24. Experience with CORBA CORBA simplifies middleware development
Fits well in OO development
but …
Actual ORB implementations require several MB of memory. This restricts use of Middleware.
Quality ORBs are rare birds
Can we stick with ORBacus?

25. Some hick-ups
The first “commercial” ORB which we acquired for LynxOS was unusable
We had to improve performance of subscription updates (batch update)
Any is inefficient, we switched to use variants instead
Strategy to deal with “misbehaving” subscription clients: unreachable, slow etc.
Mostly TCP, not CORBA phenomena

26. References
The Web page of the Controls Middleware project:
K. Kostro, N Trofimov, V. Baggiolini, F. Calderini, F. Chevrier, S. Jensen, R. Swoboda “Controls Middleware - The New Generation”, EPAC 2002, Paris, 2-7 June 2002
N. Trofimow, V. Baggiolini, S. Jensen, K. Kostro, F. Di Maio, A. Risso, “Remote Device Access in the New Accelerator Controls”, ICALEPCS ’01, San Jose, USA, Nov