Is there a generic type for UIMA annotation features?

Question

Is there a generic type, similar to Object in Java, that would allow values of different types to be set to it?

<typeDescription>
    <name>com.example.Annotation</name>
    <description></description>
    <supertypeName>uima.tcas.Annotation</supertypeName>
    <features>
        <featureDescription>
            <name>exampleFeature</name>
            <description>An example feature</description>
            <rangeTypeName>uima.cas.Generic</rangeTypeName>
        </featureDescription>
    </features>
</typeDescription>

I have tried putting the following in <rangeTypeName>:

• java.lang.Object and Object This doesn't work and I get the following message when trying to generate the code using JCasGen:

  JCasGen Warning: ** Resource Initialization Error occurred while instantiating the CAS type system. Continuing, but may generate incorrectly. Caused by 'Undefined type "Object", referenced in feature "exampleFeature" declared on type "com.example.Annotation".

• uima.cas.TOP This generates the code but then gives an error when I try to call the setExampleField() method by passing it an int or String as it cannot convert them to the TOP type.

Answer 1

The uima.cas.TOP is the Object-equivalent type of UIMA. But it is slightly different from what you would expect. UIMA operates with two concepts: 1) FeatureStructure, 2) primitive types (int, boolean, etc. and String!). If you set the range of a feature to TOP, it can accept any kind of feature structure (i.e. anything that inherits from TOP), but not any of the primitive types - no auto-boxing here. If you set the range to a primitive type, then it will only accept that type.

A work-around could be to define custom types , e.g. FSInt, FSString, FSBoolean which inherit from TOP and which would have a "value" feature of the respective type (int, String, boolean). You could then set the value in that FS and assign it to a feature with range TOP.

Note: I am currently a committer on the Apache UIMA project.