Read Alfresco custom metadata via OpenCMIS?

I created a new Alfresco document, and added a custom aspect (EXIF aspect) to it.

How to get the values of this metadata via OpenCMIS/DotCMIS?

I tried the following but it does not show the EXIF metadata (nor presumably any custom aspect metadata):

foreach(IProperty property in document.Properties)
{
    if (property.IsMultiValued)
    {
         metadata.Add(property.Id, property.ValuesAsString);
    }
    else
    {
         metadata.Add(property.Id, property.ValueAsString);
    }
}

You cannot read aspect based properties without using the extension Gagravarr mentioned until Alfresco supports CMIS 1.1. As of today there are no Alfresco releases either in Enterprise Edition or Community Edition that supports CMIS 1.1. I doubt 4.2 will include CMIS 1.1 but hopefully the release after that will.