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Client Data Types

Client Data Types. Gabriele 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

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Client Data Types

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  1. Client Data Types Gabriele Carcassi Oct 12 2010

  2. 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

  3. 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

  4. 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)

  5. VDouble • Let’s start with the most common one, VDouble • Scalar<Double> • Alarm • Time • Display<Double> • Let’s go through details of all interfaces

  6. Scalar<T> • Defines: • T getValue() • Returns the value of some type.

  7. Alarm • Defines: • AlarmSeveritygetAlarmSeverity(); • 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.

  8. Time • Defines: • TimeStampgetTimeStamp(); • 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)

  9. Display<T> • Defines: • T getLower/UppterDisplayLimit(); • T getLower/UppterCtrlLimit(); • T getLower/UppterAlarmLimit(); • T getLower/UppterWarningLimit(); • String getUnits(); • NumberFormatgetFormat();

  10. 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

  11. 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

  12. Enumeration • Enum defines: • List<String> getLabels(); • Venum defines: • intgetIndex();

  13. 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

  14. 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();

  15. 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

  16. MultiScalar<T> • Defines: • List<T> getValues();

  17. 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)

  18. VTable • Defines: • intgetColumnCount(); • 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.

  19. 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

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