diff --git a/lib/coins.py b/lib/coins.py
index 6537e74..ec84b96 100644
--- a/lib/coins.py
+++ b/lib/coins.py
@@ -13,9 +13,10 @@ necessary for appropriate handling.
 
 from decimal import Decimal
 import inspect
+import struct
 import sys
 
-from lib.hash import Base58, hash160, double_sha256
+from lib.hash import Base58, hash160, double_sha256, hash_to_str
 from lib.script import ScriptPubKey
 from lib.tx import Deserializer
 
@@ -31,6 +32,7 @@ class Coin(object):
     HEADER_LEN = 80
     DEFAULT_RPC_PORT = 8332
     VALUE_PER_COIN = 100000000
+    CHUNK_SIZE=2016
 
     @staticmethod
     def coin_classes():
@@ -168,6 +170,21 @@ class Coin(object):
         '''
         return Decimal(value) / cls.VALUE_PER_COIN
 
+    @classmethod
+    def electrum_header(cls, header, height):
+        version, = struct.unpack('<I', header[:4])
+        timestamp, bits, nonce = struct.unpack('<III', header[68:80])
+
+        return {
+            'block_height': height,
+            'version': version,
+            'prev_block_hash': hash_to_str(header[4:36]),
+            'merkle_root': hash_to_str(header[36:68]),
+            'timestamp': timestamp,
+            'bits': bits,
+            'nonce': nonce,
+        }
+
 
 class Bitcoin(Coin):
     NAME = "Bitcoin"
diff --git a/server/block_processor.py b/server/block_processor.py
index 60cf37d..7397582 100644
--- a/server/block_processor.py
+++ b/server/block_processor.py
@@ -125,11 +125,15 @@ class BlockProcessor(LoggedClass):
     Coordinate backing up in case of chain reorganisations.
     '''
 
-    def __init__(self, env, daemon, on_catchup=None):
+    def __init__(self, env, daemon, on_update=None):
+        '''on_update is awaitable, and called only when caught up with the
+        daemon and a new block arrives or the mempool is updated.
+        '''
+
         super().__init__()
 
         self.daemon = daemon
-        self.on_catchup = on_catchup
+        self.on_update = on_update
 
         # Meta
         self.utxo_MB = env.utxo_MB
@@ -200,8 +204,8 @@ class BlockProcessor(LoggedClass):
         if not self.have_caught_up:
             self.have_caught_up = True
             self.logger.info('caught up to height {:,d}'.format(self.height))
-            if self.on_catchup:
-                await self.on_catchup()
+            if self.on_update:
+                await self.on_update(self.height, set())
 
     async def start(self):
         '''External entry point for block processing.
diff --git a/server/cache.py b/server/cache.py
index 3adfbe8..a9a6822 100644
--- a/server/cache.py
+++ b/server/cache.py
@@ -390,22 +390,3 @@ class FSCache(LoggedClass):
         headers = self.read_headers(height, count)
         hlen = self.coin.HEADER_LEN
         return [double_sha256(header) for header in chunks(headers, hlen)]
-
-    def encode_header(self, height):
-        if height < 0 or height > self.height + len(self.headers):
-            raise Exception('no header information for height {:,d}'
-                            .format(height))
-        header = self.read_headers(self.height, 1)
-        unpack = struct.unpack
-        version, = unpack('<I', header[:4])
-        timestamp, bits, nonce = unpack('<III', header[68:80])
-
-        return {
-            'block_height': self.height,
-            'version': version,
-            'prev_block_hash': hash_to_str(header[4:36]),
-            'merkle_root': hash_to_str(header[36:68]),
-            'timestamp': timestamp,
-            'bits': bits,
-            'nonce': nonce,
-        }
diff --git a/server/controller.py b/server/controller.py
index a7af664..898523a 100644
--- a/server/controller.py
+++ b/server/controller.py
@@ -19,7 +19,7 @@ from functools import partial
 
 from server.daemon import Daemon, DaemonError
 from server.block_processor import BlockProcessor
-from server.protocol import ElectrumX, LocalRPC
+from server.protocol import ElectrumX, LocalRPC, RPCError, JSONRPC
 from lib.hash import (sha256, double_sha256, hash_to_str,
                       Base58, hex_str_to_hash)
 from lib.util import LoggedClass
@@ -35,11 +35,12 @@ class Controller(LoggedClass):
         super().__init__()
         self.loop = loop
         self.env = env
+        self.coin = env.coin
         self.daemon = Daemon(env.daemon_url)
         self.block_processor = BlockProcessor(env, self.daemon,
-                                              on_catchup=self.start_servers)
+                                              on_update=self.on_update)
+        JSONRPC.init(self.block_processor, self.coin)
         self.servers = []
-        self.sessions = set()
         self.addresses = {}
         self.jobs = asyncio.Queue()
         self.peers = {}
@@ -57,15 +58,18 @@ class Controller(LoggedClass):
             self.loop.add_signal_handler(getattr(signal, signame),
                                          partial(self.on_signal, signame))
 
+    async def on_update(self, height, touched):
+        if not self.servers:
+            self.servers = await self.start_servers()
+        ElectrumX.notify(height, touched)
+
     async def start_servers(self):
         '''Start listening on RPC, TCP and SSL ports.
 
         Does not start a server if the port wasn't specified.  Does
         nothing if servers are already running.
         '''
-        if self.servers:
-            return
-
+        servers = []
         env = self.env
         loop = self.loop
 
@@ -73,14 +77,14 @@ class Controller(LoggedClass):
         if env.rpc_port is not None:
             host = 'localhost'
             rpc_server = loop.create_server(protocol, host, env.rpc_port)
-            self.servers.append(await rpc_server)
+            servers.append(await rpc_server)
             self.logger.info('RPC server listening on {}:{:d}'
                              .format(host, env.rpc_port))
 
         protocol = partial(ElectrumX, self, self.daemon, env)
         if env.tcp_port is not None:
             tcp_server = loop.create_server(protocol, env.host, env.tcp_port)
-            self.servers.append(await tcp_server)
+            servers.append(await tcp_server)
             self.logger.info('TCP server listening on {}:{:d}'
                              .format(env.host, env.tcp_port))
 
@@ -91,10 +95,12 @@ class Controller(LoggedClass):
                                         keyfile=env.ssl_keyfile)
             ssl_server = loop.create_server(protocol, env.host, env.ssl_port,
                                             ssl=ssl_context)
-            self.servers.append(await ssl_server)
+            servers.append(await ssl_server)
             self.logger.info('SSL server listening on {}:{:d}'
                              .format(env.host, env.ssl_port))
 
+        return servers
+
     def stop(self):
         '''Close the listening servers.'''
         for server in self.servers:
@@ -107,14 +113,6 @@ class Controller(LoggedClass):
         for task in asyncio.Task.all_tasks(self.loop):
             task.cancel()
 
-    def add_session(self, session):
-        '''Add a session representing one incoming connection.'''
-        self.sessions.add(session)
-
-    def remove_session(self, session):
-        '''Remove a session.'''
-        self.sessions.remove(session)
-
     def add_job(self, coro):
         '''Queue a job for asynchronous processing.'''
         self.jobs.put_nowait(coro)
@@ -174,12 +172,29 @@ class Controller(LoggedClass):
     def height(self):
         return self.block_processor.height
 
-    def get_current_header(self):
-        return self.block_processor.get_current_header()
-
     def get_history(self, hash168):
         history = self.block_processor.get_history(hash168, limit=None)
         return [
             {'tx_hash': hash_to_str(tx_hash), 'height': height}
             for tx_hash, height in history
         ]
+
+    def get_chunk(self, index):
+        '''Return header chunk as hex.  Index is a non-negative integer.'''
+        chunk_size = self.coin.CHUNK_SIZE
+        next_height = self.height() + 1
+        start_height = min(index * chunk_size, next_height)
+        count = min(next_height - start_height, chunk_size)
+        return self.block_processor.read_headers(start_height, count).hex()
+
+    def get_balance(self, hash168):
+        confirmed = self.block_processor.get_balance(hash168)
+        unconfirmed = -1  # FIXME
+        return {'confirmed': confirmed, 'unconfirmed': unconfirmed}
+
+    def list_unspent(self, hash168):
+        utxos = self.block_processor.get_utxos_sorted(hash168)
+        return tuple({'tx_hash': hash_to_str(utxo.tx_hash),
+                      'tx_pos': utxo.tx_pos, 'height': utxo.height,
+                      'value': utxo.value}
+                     for utxo in utxos)
diff --git a/server/daemon.py b/server/daemon.py
index aaef6c1..5fddde6 100644
--- a/server/daemon.py
+++ b/server/daemon.py
@@ -71,8 +71,7 @@ class Daemon(LoggedClass):
                     msg = 'daemon still warming up.'
                     secs = 30
                 else:
-                    msg = '{}'.format(errs)
-                    raise DaemonError(msg)
+                    raise DaemonError(errs)
 
             self.logger.error('{}.  Sleeping {:d}s and trying again...'
                               .format(msg, secs))
@@ -90,6 +89,28 @@ class Daemon(LoggedClass):
         # Convert hex string to bytes
         return [bytes.fromhex(block) for block in blocks]
 
+    async def mempool_hashes(self):
+        '''Return the hashes of the txs in the daemon's mempool.'''
+        return await self.send_single('getrawmempool')
+
+    async def estimatefee(self, params):
+        '''Return the fee estimate for the given parameters.'''
+        return await self.send_single('estimatefee', params)
+
+    async def relayfee(self):
+        '''The minimum fee a low-priority tx must pay in order to be accepted
+        to the daemon's memory pool.'''
+        net_info = await self.send_single('getnetworkinfo')
+        return net_info['relayfee']
+
+    async def getrawtransaction(self, hex_hash):
+        '''Return the serialized raw transaction with the given hash.'''
+        return await self.send_single('getrawtransaction', (hex_hash, 0))
+
+    async def sendrawtransaction(self, params):
+        '''Broadcast a transaction to the network.'''
+        return await self.send_single('sendrawtransaction', params)
+
     async def height(self):
         '''Query the daemon for its current height.'''
         self._height = await self.send_single('getblockcount')
diff --git a/server/protocol.py b/server/protocol.py
index 2d11b7a..acedfea 100644
--- a/server/protocol.py
+++ b/server/protocol.py
@@ -11,44 +11,55 @@
 import asyncio
 import codecs
 import json
+import struct
 import traceback
 from functools import partial
 
+from server.daemon import DaemonError
 from lib.util import LoggedClass
 from server.version import VERSION
 
 
-class Error(Exception):
-    BAD_REQUEST = 1
-    INTERNAL_ERROR = 2
+class RPCError(Exception):
+    '''RPC handlers raise this error.'''
+
+
+def json_notification(method, params):
+    '''Create a json notification.'''
+    return {'id': None, 'method': method, 'params': params}
 
 
 class JSONRPC(asyncio.Protocol, LoggedClass):
-    '''Base class that manages a JSONRPC connection.
-
-    When a request comes in for an RPC method M, then a member
-    function handle_M is called with the request params array, except
-    that periods in M are replaced with underscores.  So a RPC call
-    for method 'blockchain.estimatefee' will be passed to
-    handle_blockchain_estimatefee.
-    '''
+    '''Base class that manages a JSONRPC connection.'''
+    SESSIONS = set()
+    BLOCK_PROCESSOR = None
+    COIN = None
 
     def __init__(self, controller):
         super().__init__()
         self.controller = controller
         self.parts = []
+        self.send_count = 0
+        self.send_size = 0
+        self.error_count = 0
+        self.subscribe_headers = False
+        self.subscribe_height = False
+        self.notified_height = None
 
     def connection_made(self, transport):
         '''Handle an incoming client connection.'''
         self.transport = transport
         self.peername = transport.get_extra_info('peername')
         self.logger.info('connection from {}'.format(self.peername))
-        self.controller.add_session(self)
+        self.SESSIONS.add(self)
 
     def connection_lost(self, exc):
         '''Handle client disconnection.'''
-        self.logger.info('disconnected: {}'.format(self.peername))
-        self.controller.remove_session(self)
+        self.logger.info('{} disconnected.  '
+                         'Sent {:,d} bytes in {:,d} messages {:,d} errors'
+                         .format(self.peername, self.send_size,
+                                 self.send_count, self.error_count))
+        self.SESSIONS.remove(self)
 
     def data_received(self, data):
         '''Handle incoming data (synchronously).
@@ -79,40 +90,129 @@ class JSONRPC(asyncio.Protocol, LoggedClass):
         '''Called asynchronously.'''
         error = result = None
         try:
-            result = await self.json_handler(request)
-        except Error as e:
-            error = {'code': e.args[0], 'message': e.args[1]}
-        except asyncio.CancelledError:
-            raise
-        except Exception as e:
-            # This should be considered a bug and fixed
-            traceback.print_exc()
-            error = {'code': Error.INTERNAL_ERROR, 'message': str(e)}
-
+            handler = self.rpc_handler(request.get('method'),
+                                       request.get('params', []))
+            result = await handler()
+        except RPCError as e:
+            self.error_count += 1
+            error = {'code': 1, 'message': e.args[0]}
         payload = {'id': request.get('id'), 'error': error, 'result': result}
-        try:
-            data = json.dumps(payload) + '\n'
-        except TypeError:
-            msg = 'cannot JSON encode response to request {}'.format(request)
-            self.logger.error(msg)
-            error = {'code': Error.INTERNAL_ERROR, 'message': msg}
-            payload = {'id': request.get('id'), 'error': error, 'result': None}
-            data = json.dumps(payload) + '\n'
-        self.transport.write(data.encode())
+        self.json_send(payload)
 
-    async def json_handler(self, request):
-        method = request.get('method')
+    def json_send(self, payload):
+        data = (json.dumps(payload) + '\n').encode()
+        self.transport.write(data)
+        self.send_count += 1
+        self.send_size += len(data)
+
+    def rpc_handler(self, method, params):
         handler = None
         if isinstance(method, str):
-            handler_name = 'handle_{}'.format(method.replace('.', '_'))
-            handler = getattr(self, handler_name, None)
+            handler = self.handlers.get(method)
         if not handler:
             self.logger.info('unknown method: {}'.format(method))
-            raise Error(Error.BAD_REQUEST, 'unknown method: {}'.format(method))
-        params = request.get('params', [])
+            raise RPCError('unknown method: {}'.format(method))
+
         if not isinstance(params, list):
-            raise Error(Error.BAD_REQUEST, 'params should be an array')
-        return await handler(params)
+            raise RPCError('params should be an array')
+
+        return partial(handler, self, params)
+
+    @classmethod
+    def tx_hash_from_param(cls, param):
+        '''Raise an RPCError if the parameter is not a valid transaction
+        hash.'''
+        if isinstance(param, str) and len(param) == 64:
+            try:
+                bytes.fromhex(param)
+                return param
+            except ValueError:
+                pass
+        raise RPCError('parameter should be a transaction hash: {}'
+                       .format(param))
+
+    @classmethod
+    def hash168_from_param(cls, param):
+        if isinstance(param, str):
+            try:
+                return cls.COIN.address_to_hash168(param)
+            except:
+                pass
+        raise RPCError('parameter should be a valid address: {}'.format(param))
+
+    @classmethod
+    def non_negative_integer_from_param(cls, param):
+        if isinstance(param, int) and param >= 0:
+            return param
+        raise RPCError('param should be a non-negative integer: {}'
+                       .format(param))
+
+    @classmethod
+    def extract_hash168(cls, params):
+        if len(params) == 1:
+            return cls.hash168_from_param(params[0])
+        raise RPCError('params should contain a single address: {}'
+                       .format(params))
+
+    @classmethod
+    def extract_non_negative_integer(cls, params):
+        if len(params) == 1:
+            return cls.non_negative_integer_from_param(params[0])
+        raise RPCError('params should contain a non-negative integer: {}'
+                       .format(params))
+
+    @classmethod
+    def require_empty_params(cls, params):
+        if params:
+            raise RPCError('params should be empty: {}'.format(params))
+
+    @classmethod
+    def init(cls, block_processor, coin):
+        cls.BLOCK_PROCESSOR = block_processor
+        cls.COIN = coin
+
+    @classmethod
+    def height(cls):
+        '''Return the current height.'''
+        return cls.BLOCK_PROCESSOR.height
+
+    @classmethod
+    def electrum_header(cls, height=None):
+        '''Return the binary header at the given height.'''
+        if not 0 <= height <= cls.height():
+            raise RPCError('height {:,d} out of range'.format(height))
+        header = cls.BLOCK_PROCESSOR.read_headers(height, 1)
+        return cls.COIN.electrum_header(header, height)
+
+    @classmethod
+    def current_electrum_header(cls):
+        '''Used as response to a headers subscription request.'''
+        return cls.electrum_header(cls.height())
+
+    @classmethod
+    def notify(cls, height, touched):
+        '''Notify electrum clients about height changes and touched
+        addresses.'''
+        headers_payload = json_notification(
+            'blockchain.headers.subscribe',
+            (cls.electrum_header(height), ),
+        )
+        height_payload = json_notification(
+            'blockchain.numblocks.subscribe',
+            (height, ),
+        )
+        for session in cls.SESSIONS:
+            if height != session.notified_height:
+                session.notified_height = height
+                if session.subscribe_headers:
+                    session.json_send(headers_payload)
+                if session.subscribe_height:
+                    session.json_send(height_payload)
+
+            for hash168 in session.hash168s.intersection(touched):
+                payload = json_notification('blockchain.address.subscribe',
+                                            (Base58.encode_check(hash168), ))
+                session.json_send(payload)
 
 
 class ElectrumX(JSONRPC):
@@ -122,60 +222,138 @@ class ElectrumX(JSONRPC):
         super().__init__(controller)
         self.daemon = daemon
         self.env = env
-        self.addresses = set()
-        self.subscribe_headers = False
+        self.hash168s = set()
+        rpcs = [(
+            'blockchain',
+            'address.get_balance address.get_history address.get_mempool '
+            'address.get_proof address.listunspent address.subscribe '
+            'block.get_header block.get_chunk estimatefee headers.subscribe '
+            'numblocks.subscribe relayfee transaction.broadcast '
+            'transaction.get transaction.get_merkle utxo.get_address'),
+        (
+            'server',
+            'banner donation_address peers.subscribe version'),
+        ]
+        self.handlers = {'.'.join([prefix, suffix]):
+                         getattr(self.__class__, suffix.replace('.', '_'))
+                         for prefix, suffixes in rpcs
+                         for suffix in suffixes.split()}
 
-    def params_to_hash168(self, params):
-        if len(params) != 1:
-            raise Error(Error.BAD_REQUEST,
-                        'params should contain a single address')
-        address = params[0]
-        try:
-            return self.env.coin.address_to_hash168(address)
-        except:
-            raise Error(Error.BAD_REQUEST,
-                        'invalid address: {}'.format(address))
+    @classmethod
+    def watched_address_count(cls):
+        return sum(len(session.hash168s) for session in self.SESSIONS
+                   if isinstance(session, cls))
 
-    async def handle_blockchain_address_get_history(self, params):
-        hash168 = self.params_to_hash168(params)
+    # --- blockchain commands
+
+    async def address_get_balance(self, params):
+        hash168 = self.extract_hash168(params)
+        return self.controller.get_balance(hash168)
+
+    async def address_get_history(self, params):
+        hash168 = self.extract_hash168(params)
         return self.controller.get_history(hash168)
 
-    async def handle_blockchain_address_subscribe(self, params):
-        hash168 = self.params_to_hash168(params)
+    async def address_get_mempool(self, params):
+        hash168 = self.extract_hash168(params)
+        raise RPCError('get_mempool is not yet implemented')
+
+    async def address_get_proof(self, params):
+        hash168 = self.extract_hash168(params)
+        raise RPCError('get_proof is not yet implemented')
+
+    async def address_listunspent(self, params):
+        hash168 = self.extract_hash168(params)
+        return self.controller.list_unspent(hash168)
+
+    async def address_subscribe(self, params):
+        hash168 = self.extract_hash168(params)
+        self.hash168s.add(hash168)
         status = self.controller.address_status(hash168)
         return status.hex() if status else None
 
-    async def handle_blockchain_estimatefee(self, params):
-        result = await self.daemon.send_single('estimatefee', params)
-        return result
+    async def block_get_chunk(self, params):
+        index = self.extract_non_negative_integer(params)
+        return self.controller.get_chunk(index)
 
-    async def handle_blockchain_headers_subscribe(self, params):
+    async def block_get_header(self, params):
+        height = self.extract_non_negative_integer(params)
+        return self.electrum_header(height)
+
+    async def estimatefee(self, params):
+        return await self.daemon.estimatefee(params)
+
+    async def headers_subscribe(self, params):
+        self.require_empty_params(params)
         self.subscribe_headers = True
-        return self.controller.get_current_header()
+        return self.current_electrum_header()
 
-    async def handle_blockchain_relayfee(self, params):
+    async def numblocks_subscribe(self, params):
+        self.require_empty_params(params)
+        self.subscribe_height = True
+        return self.height()
+
+    async def relayfee(self, params):
         '''The minimum fee a low-priority tx must pay in order to be accepted
-        to this daemon's memory pool.
+        to the daemon's memory pool.'''
+        self.require_empty_params(params)
+        return await self.daemon.relayfee()
+
+    async def transaction_broadcast(self, params):
+        '''Pass through the parameters to the daemon.
+
+        An ugly API: current Electrum clients only pass the raw
+        transaction in hex and expect error messages to be returned in
+        the result field.  And the server shouldn't be doing the client's
+        user interface job here.
         '''
-        net_info = await self.daemon.send_single('getnetworkinfo')
-        return net_info['relayfee']
+        try:
+            tx_hash = await self.daemon.sendrawtransaction(params)
+            self.logger.info('sent tx: {}'.format(tx_hash))
+            return tx_hash
+        except DaemonError as e:
+            errors = e.args[0]
+            error = errors[0]
+            message = error['message']
+            self.logger.info('sendrawtransaction: {}'.format(message))
+            if 'non-mandatory-script-verify-flag' in message:
+                return (
+                    'Your client produced a transaction that is not accepted '
+                    'by the network any more.  Please upgrade to Electrum '
+                    '2.5.1 or newer.'
+                )
 
-    async def handle_blockchain_transaction_get(self, params):
-        if len(params) != 1:
-            raise Error(Error.BAD_REQUEST,
-                        'params should contain a transaction hash')
-        tx_hash = params[0]
-        return await self.daemon.send_single('getrawtransaction', (tx_hash, 0))
+            return (
+                'The transaction was rejected by network rules.  ({})\n[{}]'
+                .format(message, params[0])
+            )
 
-    async def handle_blockchain_transaction_get_merkle(self, params):
-        if len(params) != 2:
-            raise Error(Error.BAD_REQUEST,
-                        'params should contain a transaction hash and height')
-        tx_hash, height = params
-        return await self.controller.get_merkle(tx_hash, height)
+    async def transaction_get(self, params):
+        '''Return the serialized raw transaction.'''
+        # For some reason Electrum passes a height.  Don't require it
+        # in anticipation it might be dropped in the future.
+        if 1 <= len(params) <= 2:
+            tx_hash = self.tx_hash_from_param(params[0])
+            return await self.daemon.getrawtransaction(tx_hash)
 
-    async def handle_server_banner(self, params):
+        raise RPCError('params wrong length: {}'.format(params))
+
+    async def transaction_get_merkle(self, params):
+        if len(params) == 2:
+            tx_hash = self.tx_hash_from_param(params[0])
+            height = self.non_negative_integer_from_param(params[1])
+            return await self.controller.get_merkle(tx_hash, height)
+
+        raise RPCError('params should contain a transaction hash and height')
+
+    async def utxo_get_address(self, params):
+        pass # TODO
+
+    # --- server commands
+
+    async def banner(self, params):
         '''Return the server banner.'''
+        self.require_empty_params(params)
         banner = 'Welcome to Electrum!'
         if self.env.banner_file:
             try:
@@ -186,23 +364,25 @@ class ElectrumX(JSONRPC):
                                   .format(self.env.banner_file, e))
         return banner
 
-    async def handle_server_donation_address(self, params):
+    async def donation_address(self, params):
         '''Return the donation address as a string.
 
         If none is specified return the empty string.
         '''
+        self.require_empty_params(params)
         return self.env.donation_address
 
-    async def handle_server_peers_subscribe(self, params):
+    async def peers_subscribe(self, params):
         '''Returns the peer (ip, host, ports) tuples.
 
         Despite the name electrum-server does not treat this as a
         subscription.
         '''
+        self.require_empty_params(params)
         peers = self.controller.get_peers()
         return tuple(peers.values())
 
-    async def handle_server_version(self, params):
+    async def version(self, params):
         '''Return the server version as a string.'''
         return VERSION
 
@@ -210,24 +390,28 @@ class ElectrumX(JSONRPC):
 class LocalRPC(JSONRPC):
     '''A local TCP RPC server for querying status.'''
 
-    async def handle_getinfo(self, params):
+    def __init__(self):
+        super().__init__()
+        cmds = 'getinfo sessions numsessions peers numpeers'.split()
+        self.handlers = {cmd: getattr(self.__class__, cmd) for cmd in cmds}
+
+    async def getinfo(self, params):
         return {
-            'blocks': self.controller.height(),
+            'blocks': self.height(),
             'peers': len(self.controller.get_peers()),
-            'sessions': len(self.controller.sessions),
-            'watched': sum(len(s.addresses) for s in self.controller.sessions
-                           if isinstance(s, ElectrumX)),
+            'sessions': len(self.SESSIONS),
+            'watched': ElectrumX.watched_address_count(),
             'cached': 0,
         }
 
-    async def handle_sessions(self, params):
+    async def sessions(self, params):
         return []
 
-    async def handle_numsessions(self, params):
-        return len(self.controller.sessions)
+    async def numsessions(self, params):
+        return len(self.SESSIONS)
 
-    async def handle_peers(self, params):
+    async def peers(self, params):
         return tuple(self.controller.get_peers().keys())
 
-    async def handle_numpeers(self, params):
+    async def numpeers(self, params):
         return len(self.controller.get_peers())