updating README

Author: geospatial-jeff

README.md

@@ -9,8 +9,9 @@ python setup.py develop
 ```
 
 # Usage
-Use the [stac-updater CLI](stac_updater/cli.py) to build and deploy your service.  Updating a static collection, for example, is accomplished as follows:
+Use the [stac-updater CLI](stac_updater/cli.py) to build and deploy your service.
 
+## Update Static Collection
 ```
 # Start a new service
 stac-updater new-service
@@ -25,4 +26,38 @@ stac-updater modify-kickoff --type s3 --bucket_name stac-updater-kickoff
 stac-updater deploy
 ```
 
-Once deployed, any STAC Item uploaded to the `stac-updater-kickoff` bucket will be ingested by the service and added to the `https://stac.com/landsat-8-l1/catalog.json` collection.
+Once deployed, any STAC Item uploaded to the `stac-updater-kickoff` bucket will be ingested by the service and added to the `https://stac.com/landsat-8-l1/catalog.json` collection.  Regardless of event source, the service expects the following JSON payload:
+
+| Field Name | Type  | Description | Example |
+| ---------- | ----- | ----------- | ------- |
+| stac_item  | dict  | **REQUIRED.** [STAC Item](https://github.com/radiantearth/stac-spec/tree/master/item-spec) to ingest into collection. | [link](https://github.com/radiantearth/stac-spec/blob/dev/item-spec/examples/sample-full.json) |
+| path  | str  | String pattern indicating subcatalogs.  Used by [sat-stac](https://github.com/sat-utils/sat-stac/blob/master/tutorial-1.ipynb#Views) to automatically build sub catalogs from item properties. | '${landsat:path}/${landsat:row}' |
+| filename  | str  | String pattern indicating filename. Used by [sat-stac](https://github.com/sat-utils/sat-stac/blob/master/tutorial-1.ipynb#Views) to automatically build item filename from item properties.| '${date}/${id}' |
+
+Each call to `update-collection` tells the services to update a single collection.  Updating multiple collections within a single deployment is accomplished with multiple calls to `update-collection`.  When updating multiple collections, the services uses a SNS fanout pattern to distribute messages across multiple queues (1 queue per collection).
+
+![abc](docs/images/update-collection.png)
+
+## SNS Notifications
+You may additionally deploy a SNS topic which publishes messages whenever a STAC Item is succesfully uploaded to a collection.
+
+```
+# Add SNS notification
+stac-updater add-notifications --topic_name stac-updater-notifications
+```
+
+Once deployed, end-users may subscribe to the newly created SNS topic to be notified when new items are added.  The SNS Topic supports filtering on bbox and collection through a SNS Filter Policy.  The following policy notifies a subscriber only when a new STAC Item is added to the `landsat-8-l1` catalog within a 1x1 degree bounding box.
+
+```json
+{
+	"bbox.xmin": [{"numeric":[">=",-118]}],
+	"bbox.ymin": [{"numeric":[">=",33]}],
+	"bbox.xmax": [{"numeric":["<=",-117]}],
+	"bbox.ymax": [{"numeric":["<=",34]}],
+	"collection": ["landsat-8-l1"]
+}
+```
+
+# TODOS
+- Add support for dynamic catalogs ([sat-api](https://github.com/sat-utils/sat-api), [staccato](https://github.com/boundlessgeo/staccato)).
+- Add aggregator service for metrics/logging etc.