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 # Architecture
 
 ![](datasheet-server-graphic.jpg)
+
+Datasheet Server uses the architecture diagrammed above to allow effective
+management of the sheets it represents.
+
+It exposes an API with four endpoints:
+ * `/:sheet/:tab/:resource` - the primary means of accessing data in the
+     server. The name of a sheet is specified in
+     [sheets_config.js](https://github.com/forensic-architecture/datasheet-server/blob/develop/src/sheets_config.js#L7).
+     Each tab on the sheet is in lower case, with spaces replaced by
+     underscores. The resource name is the same as the name of the blueprinter
+     specified for the tab is sheets_config.js.
+ * `/:sheet/:tab/:resource/:id` - when the resource is a list, items in the list
+     can be accessed individually as well.
+ * `/update` - when this route is queried with a GET request, each of the
+     fetchers in the server will update their models from the relevant sheet.
+ * `/blueprints` - a JSON object that represents all available sheets, tabs, and
+     resources in the server.
+
+# Controller
+The [controller](https://github.com/forensic-architecture/datasheet-server/blob/develop/src/lib/Controller.js)
+manages all of the fetchers in the server. Its `update` triggers the update
+mechanisms of all the `update`s in the fetchers it manages. Its `retrieve` and
+`retrieveFrag` methods find the appropriate fetcher, and trigger its 
+respectively named method. Its `bluerprints` method collects the blueprints
+from all fetchers, and presents them as a single list.
+
+# Fetcher
+The [fetcher](https://github.com/forensic-architecture/datasheet-server/blob/develop/src/lib/Fetcher.js)
+is the most complex component in datasheet server. Its responsiblity is to
+interface with a sheet, and store the data from that sheet in a model. It also
+makes information from that model available to the controller.
+
+# Model
+The model layer is an [interface](https://github.com/forensic-architecture/datasheet-server/blob/develop/src/models/Interface.js)
+that specifies how stored data must be made available to a fetcher. The
+implementation of the model layer ([StoreJson](https://github.com/forensic-architecture/datasheet-server/blob/develop/src/models/StoreJson.js)
+is one example) determines the time and space complexity of retrieval.
+