Hi,
For very very large datasets or images I developed a nodejs interface to hdf5 https://github.com/HDF-NI/hdf5.node. For bringing the view finder hyperslab to the client visualization before the whole image or dataset ever gets transported for better user experience it would be nice to request the hyperslab dimensions and retrieve that much data. Then tile out from there as the user pans a map, a medical image, another slice or scientific data such as electron densities or afm surfaces.