1396 - OAuth Spike (#252)

* updated README for ArcGIS OAuth

* using other readme instead

Author: danbenner-vega

plugins/arcgis/README.md

@@ -1,9 +1,9 @@
 # Build with arcgis plugin
+> This plugin allows for MAGE observation data to be passed to an Arcgis feature service. Follow the instructions in the root README.
 
-This plugin allows for MAGE observation data to be passed to an Arcgis feature service.
-Follow the instructions in the root README. After completing the web-app package install and build in the 'Building from source' section:
+## Build ArcGIS plugin
+- After completing the web-app package install and build in the 'Building from source' section:
 
-Build arcgis plugin:
 ```bash
 cd plugins/arcgis/service
 npm ci
@@ -17,4 +17,28 @@ npm link ../../../web-app # **IMPORTANT** see root README
 npm run build
 ```
 
-Continue to install dependencies in the `instance` package as instructed in the root README. 
+- Continue to install dependencies in the `instance` package as instructed in the root README.
+
+## Setting up OAuth for Feature Layers
+
+### [ArcGIS](`https://arcgis.geointnext.com/arcgis/home/content.html`) Website
+- *Content* -> *New Item (button)* -> *Developer Credentials*
+  + *Redirect URLs*
+    - `https://{mage-server-url}@ngageoint/mage.arcgis.service/oauth/authenticate`
+      + Mage Server URL example: `magedevd.geointnext.com/plugins/`
+  + *Application Environment*: can be left as *Multiple*
+  + *URL*: optional
+- After creating the new OAuth *app*/credentials
+  + Write down ***Client ID***
+- *Content* -> any *Feature Layer*
+  + Write down ***URL*** (bottom-right)
+
+### Mage ***Admin*** (shield icon)
+- ArcGIS *tab* -> *Feature Layers* -> *Add Feature Service*
+  + *URL*: copied from *Feature Layer* above
+  + *Authentication*: *OAuth*
+    - *Client Id*: copied from *OAuth Client Id* above
+  + Click *Create Feature*
+- You will know it works if it redirects:
+  + *Request for Permission* pop-up with the new OAuth you just created.
+  + click *Allow* -> it will redirect *back* to the Mage server