WebAPI: Add resolutions and spatialUnits to mldataset

CHANGES.md

@@ -12,6 +12,13 @@
   These openers and writers are available to any file system data store, 
   e.g., `"file"`, `"s3"`.
 
+* `xcube serve` now provides new metadata details of a multilevel dataset:
+    - The spatial unit of the dataset is now given by property `spatialUnits`
+    - The resolutions are now given by property `resolutions` and provide
+      the average x,y resolutions for each level of the dataset given in
+      the spatial units of the dataset's CRS.
+
+
 ### Other changes
 
 * Added two new versions of the xcube logo, one for dark and one for light themes,

test/webapi/datasets/test_controllers.py

@@ -71,6 +71,8 @@ def test_dataset_with_details(self):
             self.assertIsInstance(dataset.get("bbox"), (tuple, list))
             self.assertIsInstance(dataset.get("geometry"), dict)
             self.assertIsInstance(dataset.get("spatialRef"), str)
+            self.assertIsInstance(dataset.get("resolutions"), (tuple, list))
+            self.assertIsInstance(dataset.get("spatialUnits"), str)
             self.assertNotIn("rgbSchema", dataset)
             if dataset["id"] == "demo":
                 demo_dataset = dataset

xcube/webapi/datasets/controllers.py

@@ -224,6 +224,8 @@ def get_dataset(
     dataset_dict["bbox"] = list(ds_bbox)
     dataset_dict["geometry"] = get_bbox_geometry(dataset_bounds, transformer)
     dataset_dict["spatialRef"] = crs.to_string()
+    dataset_dict["resolutions"] = list(ml_ds.avg_resolutions)
+    dataset_dict["spatialUnits"] = ml_ds.grid_mapping.spatial_unit_name
 
     variable_dicts = []
     dim_names = set()