add documentation for the readme

README.md

@@ -1,10 +1,38 @@
 # stac-rucio
-A python package for managing STAC asset data locality when those assets are managed by a RUCIO server.
+A python package for managing STAC asset locality amongst a list of Rucio Storage Elements.
+
+The package is intended to work by consuming the results of queries made against a stac catalogue. For a given stac search, 
+a list of items are returned, for this list of items, the stac_rucio package supports creating replicas, 
+and creating replication rules.
+
+The stac_rucio package additionally comes with a modifier function to be used with the pystac_client,
+the modifier will check rucio for any existing replicas across the available RSEs, available replicas will
+be listed within an asset using the alternate assets stac extension. 
 
 ## Installation
 
 PyPI support coming.
 
-## Usage
 
-## Development
+## Example
+
+A notebook example is available [here](./examples/demo_example.ipynb).
+
+In the image below, we'll consinder a stac item which has no replicas or rules in rucio, but our
+user wants to bring the data into RSE #2. For this to work, we require a Non-Deterministic
+RSE ( ND-RSE ) to be configured amongst the available RSEs. A ND-RSE is a storage element in Rucio with no
+physical storage attached. This storage element is a pragmatic solution for "registering" data in Rucio where
+that data remains located at external http endpoints. Data will only be replicated in this example, when 
+the user creates a replication rule to get data from RSE #1 to RSE #2 ( but this data never actually resides at
+RSE #1 ). 
+
+![Stac Rucio](stac_rucio.png "Stac Rucio")
+
+To register the data for B01, our user needs to create a replica in the ND-RSE for this item if it does not
+already exist. For STAC collections supported by a Rucio server in this way, it would be best to create these replicas
+ahead of time, as they will always be required, and will always be registered at the same ND-RSE. When replicas are created,
+the file size needs to be provided in bytes, as well as the adler32 checksum.
+
+When the replica exists, the user needs to create a replication rule. The replication rule will instruct Rucio to copy
+data from RSE #1 to RSE #2. As the data does not actually exist at RSE #1, it will be downloaded from the original http
+endpoint exposed by the stac catalogue.

examples/demo_example.ipynb

@@ -25,21 +25,9 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 2,
+   "execution_count": null,
    "metadata": {},
-   "outputs": [
-    {
-     "ename": "NameError",
-     "evalue": "name 'stac_rucio' is not defined",
-     "output_type": "error",
-     "traceback": [
-      "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
-      "\u001b[0;31mNameError\u001b[0m                                 Traceback (most recent call last)",
-      "Cell \u001b[0;32mIn[2], line 6\u001b[0m\n\u001b[1;32m      1\u001b[0m \u001b[38;5;28;01mfrom\u001b[39;00m \u001b[38;5;21;01mpystac_client\u001b[39;00m \u001b[38;5;28;01mimport\u001b[39;00m Client\n\u001b[1;32m      3\u001b[0m \u001b[38;5;66;03m# STAC client connection, with a modifier for updating items on the fly.\u001b[39;00m\n\u001b[1;32m      4\u001b[0m eodc \u001b[38;5;241m=\u001b[39m Client\u001b[38;5;241m.\u001b[39mopen(\n\u001b[1;32m      5\u001b[0m   \u001b[38;5;124m\"\u001b[39m\u001b[38;5;124mhttps://stac.eodc.eu/api/v1\u001b[39m\u001b[38;5;124m\"\u001b[39m,\n\u001b[0;32m----> 6\u001b[0m   modifier\u001b[38;5;241m=\u001b[39m\u001b[43mstac_rucio\u001b[49m\u001b[38;5;241m.\u001b[39mrucio_item\n\u001b[1;32m      7\u001b[0m )\n",
-      "\u001b[0;31mNameError\u001b[0m: name 'stac_rucio' is not defined"
-     ]
-    }
-   ],
+   "outputs": [],
    "source": [
     "from pystac_client import Client\n",
     "\n",
@@ -128,7 +116,7 @@
    "outputs": [],
    "source": [
     "# Create replicas carries out the initial registration of the target asset at the specified RSE.\n",
-    "stac_rucio.create_replicas(items=november_list, rse=\"EODC-DATA\", target=\"mfcover\")"
+    "stac_rucio.create_replicas(items=november_list, rse=\"EODC-DATA\", targets=[\"mfcover\"])"
    ]
   },
   {
@@ -138,7 +126,7 @@
    "outputs": [],
    "source": [
     "# Create replication rules generates the rules that instruct rucio that a request has been made to copy data from one RSE to another.\n",
-    "stac_rucio.create_replication_rules(items=november_list, dst_rse=\"DESY-DCACHE\")"
+    "stac_rucio.create_replication_rules(items=november_list, dst_rse=\"DESY-DCACHE\", targets=[\"mfcover\"])"
    ]
   },
   {