Renames MARBLE.md

MARBLE.md

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+# Marble
+
+## Fallback
+
+On init, if a `fallback` file is specified, squirrel load content as first state. Allows restart without an available ETCD cluster.
+
+- If `fallback` is specified
+
+```
+-A|
+```
+
+A is the content of fallback file wrapped in `GET` action.
+
+```JSON
+{
+  "action": "GET",
+  "node": {
+    "key": "/",
+    "dir": true,
+    "nodes": []
+  }
+}
+```
+
+- If `fallback` isn't specified
+
+```
+|
+```
+
+- If `fallback` file doesn't exists
+
+```
+|
+```
+
+## Fetcher
+
+On init, squirrel fetch ETCD until success.
+
+```
+-A|
+```
+
+A is the content of ETCD wrapped in `GET` action.
+
+```JSON
+{
+  "action": "GET",
+  "node": {
+    "key": "/",
+    "dir": true,
+    "nodes": []
+  }
+}
+```
+
+On error, retry until is success.
+
+## Watcher
+
+Watch modification on ETCD cluster.
+
+```
+-A-B-C-
+```
+
+A B C are actions.
+
+`SET` action:
+```JSON
+{
+  "action": "set",
+  "node": {
+    "key": "/foo",
+    "value": "foo",
+    "modifiedIndex": 1438,
+    "createdIndex": 1438
+  },
+  "prevNode": {
+    "key": "/foo",
+    "value": "bar",
+    "modifiedIndex": 1437,
+    "createdIndex": 1437
+  }
+}
+```
+
+`DELETE` action:
+```JSON
+{
+  "action": "delete",
+  "node": {
+    "key": "/foo",
+    "modifiedIndex": 1435,
+    "createdIndex": 1434
+  },
+  "prevNode": {
+    "key": "/foo",
+    "value": "bar",
+    "modifiedIndex": 1434,
+    "createdIndex": 1434
+  }
+}
+```
+
+`RESYNC` action (server cleared and outdated the index)
+```JSON
+{
+  "action": "resync"
+}
+```
+
+## ETCD
+
+Combine `fallback`, `fetcher` and `watcher` observable.
+
+```
+-A|       // fallback
+-B|       // fetcher
+--C-D-E-  // watcher
+
+-ABC-D-E-
+```
+
+## Combiner
+
+Aggregate ETCD's events to rebuild representation of ETCD content.
+
+```
+-a-b-c- // ETCD's events
+
+------
+ \ \ \
+  A \ C
+     B
+
+-A---BC // ConcatAll
+```
+
+A & C are `SET` or `GET` events.
+B is a `RESYNC` event which is tranform to `fetch` observable.