+The on Disk Format is designed for simplicity and rsync-support
+There are 2 kinds of object, thus 2 subdirectories.
+* blobs store binary items, they are below blobs using a finename sheme of
+* metadata items store compressed json objects below 'meta'
+ the metadata files should be pretty-printed json, using the indent of 2 spaces
+The web fontend exposes 2 resource collections for blobs and meta items
+on get requests they will serve as is, put requests may only contain full content
+PUT of meta items that refer unknown blobs will be refused telling the missing blobs