ome-ngff header for zarr streaming

[leowe]

• Added an endpoint to request the OME-NGFF Header for a specific layer and a OmeNgffHeader Class
  • Note that the code assumes that the path to a mag is always in the shortened form on disk (if it is possible)
  • Note that the OmeNgffHeader class doesn't implement all fields from the standard but only the ones that we currently need
• Rewrite part of the .zarray route to use the existing ZarrHeader class

URL of deployed dev instance (used for testing):

• https://___.webknossos.xyz

Steps to test:

• Send a request to GET /data/zarr/:organization/:dataset/:layer/.zattrs, e.g. GET /data/zarr/sample_organization/l4_sample/color/.zattrs
• you should get back a Json that looks similar to this one:

{
    "multiscales": [{
        "version": "0.4",
        "name": "color",
        "axes": [{
            "name": "c",
            "type": "channel"
        }, {
            "name": "x",
            "type": "space",
            "unit": "nanometer"
        }, {
            "name": "y",
            "type": "space",
            "unit": "nanometer"
        }, {
            "name": "z",
            "type": "space",
            "unit": "nanometer"
        }],
        "datasets": [{
            "path": "1",
            "coordinateTranformations": [{
                "type": "scale",
                "scale": [1, 11.239999771118164, 11.239999771118164, 28]
            }]
        }, {
            "path": "2-2-1",
            "coordinateTranformations": [{
                "type": "scale",
                "scale": [1, 22.479999542236328, 22.479999542236328, 28]
            }]
        }, {
            "path": "4-4-1",
            "coordinateTranformations": [{
                "type": "scale",
                "scale": [1, 44.959999084472656, 44.959999084472656, 28]
            }]
        }, {
            "path": "8-8-2",
            "coordinateTranformations": [{
                "type": "scale",
                "scale": [1, 89.91999816894531, 89.91999816894531, 56]
            }]
        }, {
            "path": "16-16-4",
            "coordinateTranformations": [{
                "type": "scale",
                "scale": [1, 179.83999633789062, 179.83999633789062, 112]
            }]
        }]
    }]
}

Issues:

• fixes OME-NGFF metadata for exposed layers #6206

---

• Updated (unreleased) changelog
• Needs datastore update after deployment
• Ready for review

[fm3]

LGTM :)

I assume this is not supported for volume annotations at the moment? Would that be difficult to add? If not, it would be great if you could create another PR for that (feel free to merge this one already)

[leowe]

LGTM :)

I assume this is not supported for volume annotations at the moment? Would that be difficult to add? If not, it would be great if you could create another PR for that (feel free to merge this one already)

It shouldn't be hard to add, I'll open a PR.