Client Data Types Gabriele Carcassi Oct

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  JavaDocs (with actual documentation) at l l  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, 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 Alarm Time Display  Let’s go through details of all interfaces

Scalar  Defines: T getValue()  Returns the value of some type.

Alarm  Defines: AlarmSeverity getAlarmSeverity(); Set getAlarmStatus(); List 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  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, Alarm, Time, Display  VInt - Scalar, Alarm, Time, Display  VString - Scalar, Alarm, Time  VEnum - Scalar, Enum, Alarm, Time

Enumeration  Enum defines: List getLabels();  Venum defines: int getIndex();

Multi dimensional arrays  VDoubleArray - Array, Alarm, Time, Display  VIntArray - Array, Alarm, Time, Display  VStringArray - Array, Alarm, Time  VEnumArray - Array, Enum, Alarm, Time

Array  Defines: List 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, Alarm, Time, Display  VMultiInt: MultiScalar, Alarm, Time, Display  VMultiString: MultiScalar, Alarm, Time  VMultiEnum: MultiScalar, Enum, Alarm, Time

MultiScalar  Defines: List getValues();

Statistics  VStatistics: Statistics, Alarm, Time, Display  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