Client Data Types

Client Data TypesGabriele Carcassi

Oct 12 2010

Scope and requirements

Define client side data structures to represent data for control systems and high level applications• Indicates what goes on the wire, but it’s not what goes on

the wire Definition through Java interfaces Compatibility between Epics 3 and 4 Defined as part of PVManager for convenience, but

they do not have dependencies on PVManager• nor PVManager depends on them

References and documentation

Project available at http://pvmanager.sourceforge.net

JavaDocs (with actual documentation) at http://pvmanager.sourceforge.net/apidocs/index.html

Package org.epics.pvmanager.data

Design guidelines

All data types defined through interfaces Two types of interfaces

• Full type (e.g. VDouble, VMultiInt, VStatistics): they represent types that are actually implemented and can be asked; they all look like VXxx (where V is value)

• Partial type (e.g. Scalar<T>, Alarm, Time): they represent common parts of data across different full types; they are defined separately so that we have one definition and so that clients can code to that partial interface

Full types are made up as collections of partial types (mostly don’t define new methods)

VDouble

Let’s start with the most common one, VDouble• Scalar<Double>• Alarm• Time• Display<Double>

Let’s go through details of all interfaces

Scalar<T>

Defines:• T getValue()

Returns the value of some type.

Alarm

Defines:• AlarmSeverity getAlarmSeverity();• Set<AlarmStatusElement> getAlarmStatus();• List<AlarmStatusElement> getPossibleAlarms();

AlarmSeverity: enumeration of NONE, MINOR, MAJOR, INVALID, UNDEFINED

It can return more than one status, each status a String plus an AlarmSeverity• Note: client side. Protocol might send a byte, with Strings

only at connection or hardcoded client/server.

Time

Defines:• TimeStamp getTimeStamp();• Integer getTimeUserTag();

TimeStamp is a nanosecond accuracy instant• Investigating use of JSR-310 Date and Time API• javax.time.Instant (64 bit second + 32 bit nanosecond)

TimeUserTag can be used to identify fill patterns (improved from Epics 3)

Display<T>

Defines:• T getLower/UppterDisplayLimit();• T getLower/UppterCtrlLimit();• T getLower/UppterAlarmLimit();• T getLower/UppterWarningLimit();• String getUnits();• NumberFormat getFormat();

VDouble

VDouble is one type, and defines all those elements.

Does it mean that it provides all those elements? That every time I ask for a VDouble I get everything?

NO! You can still have partial implementations, that throw UnsupportedOperationException on the pieces that they do not implement. You can fill in with default data.

The point is to avoid 2^4 combinations

All scalar types

VDouble – Scalar<Double>, Alarm, Time, Display<Double>

VInt - Scalar<Integer>, Alarm, Time, Display<Integer>

VString - Scalar<String>, Alarm, Time VEnum - Scalar<String>, Enum, Alarm, Time

Enumeration

Enum defines:• List<String> getLabels();

Venum defines:• int getIndex();

Multi dimensional arrays

VDoubleArray - Array<Double>, Alarm, Time, Display<Double>

VIntArray - Array<Integer>, Alarm, Time, Display<Integer>

VStringArray - Array<String>, Alarm, Time VEnumArray - Array<String>, Enum, Alarm, Time

Array<T>

Defines:• List<Integer> getSizes();

The list of sizes for the multi dimensional array. One dimensional array can simply disregard this field. Difference between primitives and objects forces the array in the Full type.• VDoubleArray: double[] getArray();• VIntArray: int[] getArray();• VEnumArray, VStringArray: String[] getArray();

Multi Channel arrays

Multiple values coming from different channels (e.g. all X BPM readbacks)

VMultiDouble: MultiScalar<VDouble>, Alarm, Time, Display<Double>

VMultiInt: MultiScalar<VInt>, Alarm, Time, Display<Integer>

VMultiString: MultiScalar<VString>, Alarm, Time VMultiEnum: MultiScalar<VEnum>, Enum, Alarm,

Time

MultiScalar<T>

Defines:• List<T> getValues();

Statistics

VStatistics: Statistics, Alarm, Time, Display<Double> Statistics define:

• Double getAverage();• Double getStdDev();• Double getMin();• Double getMax();• Integer getNSamples();

Does not define how it’s calculated (different weights)

VTable

Defines:• int getColumnCount();• Class<?> getColumnType(int column);• String getColumnName(int column);• Object getColumnArray(int column);

A table is a list of columns. A column is an array of elements of a particular type plus a name.

Status

Interface definition 90% done PVManager tests and example re-implemented on

these interfaces Scalar types integrated in PVManager

• Generated by simulation and epics 3 data sources MultiDouble used for synchronized array

reconstruction