Decoding FieldList Contents with Field and Enumerated Types Dictionaries

dzmitry_shylovich
dzmitry_shylovich
in EMA

It's not very clear from the docs HOW actually I can get decoded value from the dictionary.

For example the following request:

consumer.registerClient(EmaFactory.createReqMsg().domainType(6)
    .serviceName("ELEKTRON_EDGE").name("ADDYY.PQ"), appClient);

I receive 

FieldEntry fid="15" name="CURRENCY" dataType="Enum" value="840"

How I can programmatically get corresponding value for 840 from enumtype.def dictionary? (840 "USD" US dollar)

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Best Answer

  • pimchaya.wongrukun01
    pimchaya.wongrukun01
    Answer ✓

    EMA Java does not provide
    interface to get decoded enum value. EMA Java keeps the dictionaries
    (RDMFieldDictionary and enumtype.def) internally. However, EMA Java is open
    source so you can modify it to get decoded enum value according to the enum
    dictionary it has loaded as example shown below:

    OmmEnum.java– add getEnum() method

    public com.thomsonreuters.upa.codec.Enum getEnum();

    OmmEnumImpl.java–
    implement getEnum() method

    @Override
    public com.thomsonreuters.upa.codec.Enum getEnum()
    {
    return _rsslEnum;
    }

    FieldEntry.java– add
    enumText() method

    public String enumText();

    FieldEntryImpl.java–
    implement enumText() to get decoded enum value according to enum dictionary

    @Override
    import com.thomsonreuters.upa.codec.EnumType;
    …
    public String enumText() {
    OmmEnum aEnum= ((OmmEnum)_load);
    EnumType enumType =_fieldList._rsslDictionary.entryEnumType(_rsslDictionaryEntry,aEnum.getEnum());
    if(enumType==null) {
    String errText = errorString().append("Attempt to enumText() while value(" )
    .append(String.valueOf(aEnum.enumValue())).append(") is not found in enumtype.def").toString();
    throw ommIUExcept().message(errText);
    }
    else
    return enumType.display().toString();
    }

Answers

  • Steven McCoy
    Steven McCoy

    It does not appear EMA supports enumerated types properly, it is possible with ETA.

    EnumType enumType = dictionary.entryEnumType(dictionaryEntry, fidEnumValue);
    System.out.println (enumType.display().toString());

    You have the enum value in EMA but the dictionary is completely hidden.

  • pimchaya.wongrukun01
    pimchaya.wongrukun01

    The example to use enumText() which source code is above:

    System.out.print("Fid: " + fieldEntry.fieldId() + " Name = " + fieldEntry.name() + " DataType: " + DataType.asString(fieldEntry.load().dataType()) + " Value: ");
    ...
    case DataTypes.ENUM :
    System.out.println(fieldEntry.enumValue() + "(" + fieldEntry.enumText()+")");
    break;

    The example output:

    Fid: 15 Name = CURRENCY DataType: Enum Value: 840(USD)
  • andrzej.czop
    andrzej.czop

    This is a good way to convert the enum value to text. Wanted to state that the proposed solution goes against the EMA established decoding rules. Throwing exception when the enum text is not found in the dictionary on the decoding path is "frowned upon" due to the Java performance implications. The OmmError class should be used instead. Handling of this situation is tricky since it is unclear what caused the error: network glitch, wrong dictionary, or anything else. Blindly converting the OmmEnum into the OmmError may bring "wrong" consequences to apps that do not care about the enum text.

  • andrzej.czop
    andrzej.czop

    the ETA and RFA do provide means for enum value to text conversion. The EMA is planning to add a similar capability too.

  • Olivier DAVANT
    Olivier DAVANT

    Hi @dzmitry_shylovich,

    The Elektron SDK team just released a new version ("Elektron SDK - Java - 1.1.0" available for download here) that implements the features you need. The FieldEntry::getEnumDisplay() method gives you access to String representations of Enum values. This new SDK also allows you to get access to the internal EMA dictionary. I did not test these features yet but they seem promising.

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