chore(Gossip KV): Update main README.md (hydro-project#1546)

fixes hydro-project#1531.

datastores/gossip_kv/README.md

@@ -1,56 +1,87 @@
 # Gossip Key-Value Store
 
 # Architecture
-A gossip-based key-value store library.
+The Gossip Key-Value Store is a distributed key-value store that uses a gossip protocol to replicate data across all
+members of the cluster. The key-value store is eventually consistent and is designed to be used in scenarios where 
+strict consistency is not a hard requirement.
+
+## Data Model
+Data stored in the key-value store is modelled as three level hierarchy `Namespace > Table > Rows`. 
 
 ```
-┌─────────────────────────┐    ┌─────────────────────────┐    ┌─────────────────────────┐    ┌─────────────────────────┐
-│        Process          │    │        Process          │    │        Process          │    │        Process          │
-│ ┌─────────────────────┐ │    │ ┌─────────────────────┐ │    │ ┌─────────────────────┐ │    │ ┌─────────────────────┐ │
-│ │  User Application   │ │    │ │  User Application   │ │    │ │   User Application  │ │    │ │   User Application  │ │
-│ └────────▲──┬─────────┘ │    │ └─────────▲─┬─────────┘ │    │ └─────────▲─┬─────────┘ │    │ └─────────▲─┬─────────┘ │
-│          │  │           │    │           │ │           │    │           │ │           │    │           │ │           │
-│ ┌────────┴──▼─────────┐ │    │ ┌─────────┴─▼─────────┐ │    │ ┌─────────┴─▼─────────┐ │    │ ┌─────────┴─▼─────────┐ │
-│ │   Gossip KV Store   │ │◄──►│ │   Gossip KV Store   │ │◄──►│ │   Gossip KV Store   │ │◄──►│ │   Gossip KV Store   │ │
-│ └─────────────────────┘ │    │ └─────────────────────┘ │    │ └─────────────────────┘ │    │ └─────────────────────┘ │
-└─────────────────────────┘    └─────────────────────────┘    └─────────────────────────┘    └─────────────────────────┘
+┌──────────────┐              
+│  Namespace   │             
+└─┬────────────┘              
+  │    ┌──────────────┐       
+  └────┤    Table     │       
+       └─┬────────────┘       
+         │    ┌──────────────┐
+         └────┤     Row      │
+              └──────────────┘
 ```
 
-## Data Model
-TODO: Elaborate
-* User Application manipulate data using client library
-* Replicated to all members of the gossip cluster
-* Eventually consistent
+Represented as JSON, the data model looks like this:
 
 ```json
 {
   "sys": {
     "members": {
       "member_id": {
-        "port": 1234,
-        "protocol": "v1"
+        "protocols": [
+          {
+            "name": "gossip",
+            "endpoint": "..."
+          },
+          {
+            "name": "...",
+            "endpoint": "..."
+          }
+        ]
       }
     }
   },
   "usr": {
-    "key 1": "value 1",
-    "key 2": "value 2"
+    "table_A": {
+      "key_1": "value_1",
+      "key_2": "value_2"
+    },
+    "table_B": {
+      "key_1": "value_1",
+      "key_2": "value_2"
+    }
   }
 }
 ```
-Data in divided into two sections: A `sys` section that contains system data used by the key-value store itself. The
-`usr` section contains user-defined data.
+Note that JSON is used here for illustrative purposes only - it isn't the actual data format used by the key-value 
+store.
+
+### Namespace
+A namespace is a group of tables. There are only two namespaces in the key-value store: `sys` and `usr`. The `sys` 
+namespace is reserved for system data and is used by the key-value store itself. The `usr` namespace is used for user
+data.
 
 ### `sys` Data
-The `sys` data section contains system data / state that is required by the key-value store to do it's work.
 
-#### Fields
+### Members
+The members table contains information about all the members in the cluster. Each member is identified by a unique
+`member_id`.
+
+#### Protocols
+Each member exposes a set of protocols and endpoint that can be used to communicate with it. For example, every member
+exposes the `gossip` protocol which is used by the key-value store to replicate data across the cluster.
 
 ### `usr` Data
+The `usr` namespace is used to store user data. The data is stored in tables and rows. Each table is a collection of rows
+where each row is a key-value pair. Values are stored as strings and are not interpreted by the key-value store.
+
+# Unit Testing
+A deterministic unit test suite is provided for the key-value store and the replication protocols. See the unit tests 
+on [server.rs](./kv/server.rs) for more.
 
 # Deployment
 ## Local (Minikube) Deployment
-See [Minikube Deployment](./deployment/local/README.md) for more information.
+For local development and testing, the key-value store can be deployed on Minikube. See [Minikube Deployment](./deployment/local/README.md) 
+for more information.
 
 ## AWS Deployment
-See [AWS Deployment](./deployment/aws/README.md) for more information.
+See [AWS Deployment](./deployment/aws/README.md) for more information.