Hi Anthony,

Thanks for the additional detail. I believe I have this working, and plan to check it in to the trunk (14.1), hopefully tomorrow.

I went with a similar but slightly different schema:

<?xml version="1.0"?>
<provider xmlns="http://labkey.org/study/assay/xml">
    <name>Simple Type</name>
    <description>Simple file-based assay</description>
    <primaryDataFileType>
        <namespacePrefix>testPrefix</namespacePrefix>
        <role>testRole</role>
        <fileSuffix>.tsv</fileSuffix>
        <fileSuffix default="true">.txt</fileSuffix>
    </primaryDataFileType>
    <relatedDataFileType>
        <fileSuffix>.jpg</fileSuffix>
    </relatedDataFileType>
    <relatedDataFileType>
        <namespacePrefix>XMLPrefix</namespacePrefix>
        <role>BeingXMLy</role>
        <fileSuffix>.xml</fileSuffix>
    </relatedDataFileType>
</provider>

Note that in order to get the new behavior on assayFileUpload, you'll need to give the rowId of the assay design. Otherwise, we have no way of knowing which assay provider's data type to use. I've added a note about this in the JavaScript API docs that show sample usage of the upload action.

Thanks,
Josh