Jeffrey Hill

LANSCE Requirements – a Review EPICS Paradigm Shift – a Review Status – What is Implemented What is an Abstract Data Type? Benefits of Abstract Types A New EPICS Database Field Type for

Abstract Data LANSCE Schedule Conclusion

• LANSCE, a versatile machine– Originally producing H+, H-, and polarized H- • Each with different intensities, duty factors, and even

energies – depending on experimental and medical isotope production needs

• LANSCE timing and flavoring of data– Flavoring • Selection based on - logical combinatorial of beam gates

– Timing • Selection based on - time window sampling

• Many permutations – Too many to, a-priori, install records for all of them– Subscription update filtering is needed

Distributed Control

Data Acquisitio

n

Physics Control

Open Source

Vendor Neutral

OS Neutra

l

Small Footprint

EPICS EPICS

What is a Data Acquisition System?• Replacing …

What is a Distributed Data Acquisition System? Must efficiently filter, and archive data Selecting interesting occurrences

for future processing /evaluation Flexible reconfigurable by clients at runtime▪ Don’t expect to know initially, when

designing/compiling runtime system, what experiments/filters might be devised later on

▪ Experiments/filters configured when client subscribes▪ Don’t expect to know initially, when designing/compiling

runtime system, what data aggregations will be on different data branches to different clients

Current weaknesses deploying EPICS into Data Acquisition situations?• Record processing provides good flexibility to

create event filters, but … Frequently, it isn't possible to know all of the

experiments when the IOC’s database is designed A distributed data acquisition system needs

runtime reconfiguration, initiated by client side tools

Limited data model No runtime aggregation, or user defined types

Current weaknesses deploying EPICS into Data Acquisition situations?• No support for site specific tagging of the

data If a site needs to filter for LANSCE H- beam, then

forcing this to occur based on the time-stamp Inflexible solution - from a LANSCE perspective

Our solution Site specific parasitic PV attribute data can be filtered

by the CA server

Alarm State

PV ValueSignal Data

Time Stamp

DeviceSupport

RecordSupport

DBCommon

CA Server

Record Specific ValuesDevice Specific Values

CA Client Multicast

Enhancements

CA Server Multicast

EnhancementsImplemented

MostlyImplemented

Multicast Enhancements• Simplified configuration of EPICS Systems with

Multiple IOCs on one host Installations with multiple subnets

Device Support

CA Server Event Queue

Upgrade

Database Enhancements

Database CA Service

Implemented

Under Design

LANSCE Specific

CA ServerEvent

Filtering Upgrade

CA ServerService

InterfaceUpgrade

Subscription update event filtering>camonitor "fred$F $(PV:)>30 && $(PV)<40"fred$F $(PV:)>30 && $(PV)<40 2010-06-03 07:58:47.224969 36.6466fred$F $(PV:)>30 && $(PV)<40 2010-06-03 07:58:47.227964 37.1654fred$F $(PV:)>30 && $(PV)<40 2010-06-03 07:58:47.267460 33.9427fred$F $(PV:)>30 && $(PV)<40 2010-06-03 07:58:47.276013 33.9976fred$F $(PV:)>30 && $(PV)<40 2010-06-03 07:58:47.299041 37.8033fred$F $(PV:)>30 && $(PV)<40 2010-06-03 07:58:47.319065 33.549

>camonitor "fred$F $(PV:flavor)==30 "fred$F $(PV:flavor)==30 2010-06-03 07:58:18.906049 44.1145fred$F $(PV:flavor)==30 2010-06-03 07:58:21.899019 39.2743fred$F $(PV:flavor)==30 2010-06-03 07:58:24.885000 54.3352fred$F $(PV:flavor)==30 2010-06-03 07:58:27.855063 93.9634fred$F $(PV:flavor)==30 2010-06-03 07:58:30.811997 97.7081

An Abstract Data Type is defined by Operations that may be performed on it Some mathematical constraints on these

operations Our goal, always …

• Separation of interface from implementation Isolate from each other …

The details of the internal encoding of the data structures of the implementation

The interface used to manipulate the implementation

Defining Abstract Data Type’s Interface• Specify Abstract Type’s name• Specify Abstract Type’s N methods

Specify method’s name Specify method’s I input, and O output,

parameters The parameter’s name The parameter’s data type class

i.e. integer, real, string, enumerated The parameter’s acceptable range The parameter’s optional default

Type Safety – user specified parameter must match with the specification of the interface• All parameters passed by users must match

The parameter’s name The parameter’s data type class

i.e. integer, real, string, enumerated The parameter’s acceptable range

• Input Parameters All input parameters must be supplied if the interface doesn't

specify a default• Output Parameters

All interface specified output parameters must be supplied Additional optional output parameters may be present w/o

violating interface specification If properly qualified by a standardized path name – i.e.

project/LANSCE/flavor

Users can manipulate an entity more complex than a Process Variable

Implementation is free to evolve without impacting the users

We can pass in N parameters atomically• Example, we can set the x, y, z coordinates

together as a unit We can pass out N parameters atomically

• Example, we can extend the set of parameters passed with a subscription update to include the LANSE flavor

New field type• Field size is sizeof ( pointer )• Field content

Reference counting C++ smart pointer Smart pointer points to C++ pure virtual interface

class This is the C++ interface used to interface to an

Abstract Data Type

How do database links work?• If the source is ordinary data and the destination is an

Abstract Data Type instance Not permitted unless the destination abstract type has value

set method• If the source is an Abstract Data Type instance and the

destination is ordinary data Not permitted unless the source abstract type has value get

method• If the source is an Abstract Data Type instance and and

the destination is an Abstract Data Type instance Not permitted unless Both source and destination have same Abstract Data Type

name If permitted then smart pointer in the destination is simply changed

to become a new reference to the source Or there is a matching set/get

Implementation issues• Parameter interfacing

Presumably Data Access interface is used• Parameter conversion and range checking

Presumably Data Access library is used

Implementation issues• Presumably these capabilities are evaluated

first only in new record types Therefore, minimal impact on existing

installations

Data Access, is it Easy CA?• In the EPICS community we have – Application developers (well adjusted, etc)• EPICS database, screens, matlab, python, tcl, etc

– System programmers (geeks)• Device drivers, EPICS internals, etc

• Implementing Data Access interface for particular data structure / class • System programmer job

• Data Access, is it Easy CA?• Once interfaced with Data Access –A high level (i.e. easy ca interface is available)– DA is not the data manipulation interface used by

application level users– Users use the public interface of the data structure /

class which has been interfaced

–Communities develop around the data structures / classes standardized by particular applications, industries, and instruments

Orders for our new klystrons are in place

We will provide production subscription update filtering capabilities for the LANSCE upgraded RF system and the LANSCE upgraded diagnostic systems in 2013

Prototypes will need to function considerably before that time frame

A significant upgrade for EPICS is in progress, significant milestones have been completed• Multicasting – easier configuration• Subscription update filtering – client specified

filter expression• Upgraded server event queue – optimal order

preservation and transport of user defined types• Upgraded server interface – user defined types

Others are in early design phases• New Abstract Data EPICS database field types

A delivery schedule is in place at LANSCE