Added README. More work on subscribe websocket

README.md

@@ -0,0 +1,41 @@
+# Event Monitoring with Infura
+Making use of Infura [improved eth_getLogs](https://blog.infura.io/faster-logs-and-events-e43e2fa13773)
+to observe token transactions.  
+
+Etherscan API is used to retrieve contract ABI.
+
+## Setup
+Create file config.json and enter your [Infura](https://infura.io/) project ID,
+and  [Etherscan](https://etherscan.io) API key.  
+Can also enter a default contract address.
+
+
+    {
+      "contract_address": "0x10dB9941E65DA3B7FDB0Cd05B1fd434Cb8B18158",
+      "infura_project_id": "(your Infura project id)",
+      "etherscan_api_key": "(your Etherscan API key)"
+    }
+
+
+
+## Example usage
+Example using [Tether stablecoin](https://etherscan.io/token/0xdac17f958d2ee523a2206206994597c13d831ec7).  We get
+the ABI, find the topic for Transfer event and get these.
+
+    from infmon.io import (get_contract_abi, get_event_interface, 
+        get_current_block, get_contract_events, subscribe)
+    token_address = '0xdAC17F958D2ee523a2206206994597C13D831ec7' # Tether
+    token_abi = get_contract_abi(token_address)
+    token_interface = get_event_interface(token_abi)
+    # RPC interface - get token transfers in last 10 blocks
+    transfers = get_contract_events(
+        token_address, 
+        from_block=get_current_block() - 10,  
+        topics=[token_interface['Transfer']['topic']])
+
+    # Display 
+    [token_interface['Transfer']['decode'](t) for t in transfers]
+
+    # Subscription interface - WIP not quite working yet
+    await subscribe(token_address, 
+                    topics=[token_interface['Transfer']['topic']])

infmon/io.py

@@ -26,7 +26,7 @@ def read_config():
 
 config = read_config()
 
-CONTRACT_ADDRESS = config['contract_address']
+CONTRACT_ADDRESS = config['contract_address'] if 'contract_address' in config else ''
 INFURA_PROJECT_ID = config['infura_project_id']
 ETHERSCAN_API_KEY = config['etherscan_api_key']
 
@@ -80,10 +80,19 @@ async def subscribe(contract_address=CONTRACT_ADDRESS, topics=None, infura_proje
         await ws.send(json.dumps(subscribe_args))
         subscribe_id = await ws.recv()
         print(subscribe_id)
-        # while True:
-        #     message_str = await ws.recv()
-        #     message = json.loads(message_str)
-        #     print(len(message))
+        block_hashes = defaultdict(int)
+        last_block_hash = ''
+        while True:
+            message_str = await ws.recv()
+            message = json.loads(message_str)['params']['result']
+            block_hashes[message['blockHash']] += 1
+            if message['removed']:
+                print('REMOVED')
+                print(message)
+            else:
+                if message['blockHash'] != last_block_hash:
+                    print(last_block_hash + ': ' + str(block_hashes[last_block_hash]))
+                    last_block_hash = message['blockHash']
 
 
 def get_contract_abi(