docs: add extra info on importer/updater plans

importer/README.md

@@ -1,5 +1,47 @@
 # OSM Importer Service
 
-Import data into a fresh OSM Sanbox instance.
+Import data into a fresh OSM Sandbox instance.
 
-Uses Geofabrik country data, then filters down to the users required BBOX.
+Method:
+    1. User provides BBOX to download data for.
+        - First we do a simple calculation to get centroid from BBOX.
+        - https://nominatim.org/release-docs/latest/api/Reverse
+    2. (Optional) reverse geocode the country name from BBOX area.
+    3. Download latest country data using GeoFabrik.
+    4. Filter data using `osmium` BBOX functionality.
+    5. Import the BBOX data into the sandbox db using `osmosis`.
+
+> [!NOTE]
+> While `osmium` is the most performant and best maintained tool
+> for dealing with OSM data, it does not support importing into
+> an OSM-type database (dbapi).
+>
+> It's primary purpose is for importing into an alternative
+> PostGIS database for data analysis, using PostGIS representations
+> of each geometry (the OSM db does not use PostGIS).
+>
+> As a result, the only available tool for importing into dbapi
+> format is `osmosis`, a now deprecated Java tool.
+
+## Work Modes
+
+### Option 1: Startup
+
+- Each osm-sandbox instance is throwaway.
+- The user starts sandbox with a bbox, the data is populated.
+- The mapping concludes, data is extracted, and the sandbox deleted.
+
+### Option 2: Triggered
+
+- We run one osm-sandbox instance.
+- The user triggers import for an AOI.
+- The data is imported using the workflow above.
+
+## Updating Data
+
+See the `updater` section of this repo.
+
+## Future
+
+- This is a test service to demo different approaches.
+- The end goal is to contribute to developmentseed/osm-seed.

updater/README.md

@@ -2,5 +2,13 @@
 
 Update the data in an existing OSM Sandbox instance with latest OSM data.
 
-Uses the `.osc` daily diff files provided by OSM, and filters down to the
-users required BBOX.
+- After initial load, the user may want to update the data in sandbox.
+- To sync with the current OSM database, we need to use replication data.
+- This is made available on OSM at intervals: minute, hour, day.
+    - https://wiki.openstreetmap.org/wiki/Planet.osm/diffs
+    - E.g. https://planet.osm.org/replication/day/000/004/
+- We download the daily `.osc` diff files provided by OSM.
+    - We must download each file since the date of first data import.
+    - The diffs can be filtered by BBOX using `osmium`.
+- Then the actual data import / applying of data in the db
+  will likely be done by `osmosis`.