From e86073ec960fce129c78d6268628437a3d77281c Mon Sep 17 00:00:00 2001
From: Jae Kwon <jae@tendermint.com>
Date: Tue, 4 Aug 2015 18:44:15 -0700
Subject: [PATCH] Use rpc/client/ws_client; OnStart() returns error

---
 blockchain/pool.go      |  3 +-
 blockchain/reactor.go   |  5 +--
 cmd/sim_txs/main.go     |  4 +--
 common/service.go       | 23 +++++++------
 consensus/reactor.go    | 10 ++++--
 consensus/state.go      |  5 +--
 crawler/crawl.go        | 76 ++++++++++++++++-------------------------
 crawler/log.go          |  7 ++++
 events/events.go        |  3 +-
 mempool/reactor.go      |  6 +---
 node/node.go            |  5 +--
 p2p/addrbook.go         |  3 +-
 p2p/connection.go       |  5 +--
 p2p/listener.go         |  3 +-
 p2p/peer.go             |  7 ++--
 p2p/pex_reactor.go      |  5 +--
 p2p/switch.go           |  3 +-
 rpc/client/ws_client.go | 33 ++++++++++++------
 rpc/server/handlers.go  |  3 +-
 19 files changed, 112 insertions(+), 97 deletions(-)
 create mode 100644 crawler/log.go

diff --git a/blockchain/pool.go b/blockchain/pool.go
index 518130338..9f2d042dd 100644
--- a/blockchain/pool.go
+++ b/blockchain/pool.go
@@ -68,10 +68,11 @@ func NewBlockPool(start int, requestsCh chan<- BlockRequest, timeoutsCh chan<- s
 	return bp
 }
 
-func (pool *BlockPool) OnStart() {
+func (pool *BlockPool) OnStart() error {
 	pool.BaseService.OnStart()
 	pool.repeater = NewRepeatTimer("", requestIntervalMS*time.Millisecond)
 	go pool.run()
+	return nil
 }
 
 func (pool *BlockPool) OnStop() {
diff --git a/blockchain/reactor.go b/blockchain/reactor.go
index fba51de27..fb7ff2053 100644
--- a/blockchain/reactor.go
+++ b/blockchain/reactor.go
@@ -7,12 +7,12 @@ import (
 	"reflect"
 	"time"
 
-	"github.com/tendermint/tendermint/wire"
 	. "github.com/tendermint/tendermint/common"
 	"github.com/tendermint/tendermint/events"
 	"github.com/tendermint/tendermint/p2p"
 	sm "github.com/tendermint/tendermint/state"
 	"github.com/tendermint/tendermint/types"
+	"github.com/tendermint/tendermint/wire"
 )
 
 const (
@@ -76,12 +76,13 @@ func NewBlockchainReactor(state *sm.State, store *BlockStore, sync bool) *Blockc
 	return bcR
 }
 
-func (bcR *BlockchainReactor) OnStart() {
+func (bcR *BlockchainReactor) OnStart() error {
 	bcR.BaseReactor.OnStart()
 	if bcR.sync {
 		bcR.pool.Start()
 		go bcR.poolRoutine()
 	}
+	return nil
 }
 
 func (bcR *BlockchainReactor) OnStop() {
diff --git a/cmd/sim_txs/main.go b/cmd/sim_txs/main.go
index 1e6de7514..a9b0fc01b 100644
--- a/cmd/sim_txs/main.go
+++ b/cmd/sim_txs/main.go
@@ -75,12 +75,12 @@ func main() {
 	sendTx := makeRandomTransaction(10, rootAccount.Sequence+1, root, 2, accounts)
 	fmt.Println(sendTx)
 
-	wsClient, err := rpcclient.NewWSClient("ws://" + remote + "/websocket")
+	wsClient := rpcclient.NewWSClient("ws://" + remote + "/websocket")
+	_, err = wsClient.Start()
 	if err != nil {
 		Exit(Fmt("Failed to establish websocket connection: %v", err))
 	}
 	wsClient.Subscribe(types.EventStringAccInput(sendTx.Inputs[0].Address))
-	wsClient.Start()
 
 	go func() {
 		for {
diff --git a/common/service.go b/common/service.go
index c01391dda..a992cf2d7 100644
--- a/common/service.go
+++ b/common/service.go
@@ -23,13 +23,13 @@ func NewFooService() *FooService {
 	return fs
 }
 
-func (fs *FooService) OnStart() {
+func (fs *FooService) OnStart() error {
 	fs.BaseService.OnStart() // Always call the overridden method.
 	// initialize private fields
 	// start subroutines, etc.
 }
 
-func (fs *FooService) OnStop() {
+func (fs *FooService) OnStop() error {
 	fs.BaseService.OnStop() // Always call the overridden method.
 	// close/destroy private fields
 	// stop subroutines, etc.
@@ -42,8 +42,8 @@ import "sync/atomic"
 import "github.com/tendermint/tendermint/Godeps/_workspace/src/github.com/tendermint/log15"
 
 type Service interface {
-	Start() bool
-	OnStart()
+	Start() (bool, error)
+	OnStart() error
 
 	Stop() bool
 	OnStop()
@@ -72,24 +72,24 @@ func NewBaseService(log log15.Logger, name string, impl Service) *BaseService {
 }
 
 // Implements Servce
-func (bs *BaseService) Start() bool {
+func (bs *BaseService) Start() (bool, error) {
 	if atomic.CompareAndSwapUint32(&bs.started, 0, 1) {
 		if atomic.LoadUint32(&bs.stopped) == 1 {
 			bs.log.Warn(Fmt("Not starting %v -- already stopped", bs.name), "impl", bs.impl)
-			return false
+			return false, nil
 		} else {
 			bs.log.Notice(Fmt("Starting %v", bs.name), "impl", bs.impl)
 		}
-		bs.impl.OnStart()
-		return true
+		err := bs.impl.OnStart()
+		return true, err
 	} else {
 		bs.log.Info(Fmt("Not starting %v -- already started", bs.name), "impl", bs.impl)
-		return false
+		return false, nil
 	}
 }
 
 // Implements Service
-func (bs *BaseService) OnStart() {}
+func (bs *BaseService) OnStart() error { return nil }
 
 // Implements Service
 func (bs *BaseService) Stop() bool {
@@ -131,8 +131,9 @@ func NewQuitService(log log15.Logger, name string, impl Service) *QuitService {
 }
 
 // NOTE: when overriding OnStart, must call .QuitService.OnStart().
-func (qs *QuitService) OnStart() {
+func (qs *QuitService) OnStart() error {
 	qs.Quit = make(chan struct{})
+	return nil
 }
 
 // NOTE: when overriding OnStop, must call .QuitService.OnStop().
diff --git a/consensus/reactor.go b/consensus/reactor.go
index 1778f7d56..bc400985b 100644
--- a/consensus/reactor.go
+++ b/consensus/reactor.go
@@ -8,7 +8,6 @@ import (
 	"sync"
 	"time"
 
-	"github.com/tendermint/tendermint/wire"
 	bc "github.com/tendermint/tendermint/blockchain"
 	. "github.com/tendermint/tendermint/common"
 	. "github.com/tendermint/tendermint/consensus/types"
@@ -16,6 +15,7 @@ import (
 	"github.com/tendermint/tendermint/p2p"
 	sm "github.com/tendermint/tendermint/state"
 	"github.com/tendermint/tendermint/types"
+	"github.com/tendermint/tendermint/wire"
 )
 
 const (
@@ -49,13 +49,17 @@ func NewConsensusReactor(consensusState *ConsensusState, blockStore *bc.BlockSto
 	return conR
 }
 
-func (conR *ConsensusReactor) OnStart() {
+func (conR *ConsensusReactor) OnStart() error {
 	log.Notice("ConsensusReactor ", "fastSync", conR.fastSync)
 	conR.BaseReactor.OnStart()
 	if !conR.fastSync {
-		conR.conS.Start()
+		_, err := conR.conS.Start()
+		if err != nil {
+			return err
+		}
 	}
 	go conR.broadcastNewRoundStepRoutine()
+	return nil
 }
 
 func (conR *ConsensusReactor) OnStop() {
diff --git a/consensus/state.go b/consensus/state.go
index abea5b2d0..5db6b41b2 100644
--- a/consensus/state.go
+++ b/consensus/state.go
@@ -158,7 +158,6 @@ import (
 	"time"
 
 	acm "github.com/tendermint/tendermint/account"
-	"github.com/tendermint/tendermint/wire"
 	bc "github.com/tendermint/tendermint/blockchain"
 	. "github.com/tendermint/tendermint/common"
 	. "github.com/tendermint/tendermint/consensus/types"
@@ -166,6 +165,7 @@ import (
 	mempl "github.com/tendermint/tendermint/mempool"
 	sm "github.com/tendermint/tendermint/state"
 	"github.com/tendermint/tendermint/types"
+	"github.com/tendermint/tendermint/wire"
 )
 
 var (
@@ -360,9 +360,10 @@ func (cs *ConsensusState) NewStepCh() chan *RoundState {
 	return cs.newStepCh
 }
 
-func (cs *ConsensusState) OnStart() {
+func (cs *ConsensusState) OnStart() error {
 	cs.BaseService.OnStart()
 	cs.scheduleRound0(cs.Height)
+	return nil
 }
 
 func (cs *ConsensusState) OnStop() {
diff --git a/crawler/crawl.go b/crawler/crawl.go
index 0a4058154..ac4665b26 100644
--- a/crawler/crawl.go
+++ b/crawler/crawl.go
@@ -2,13 +2,15 @@ package crawler
 
 import (
 	"fmt"
-	"github.com/tendermint/tendermint/wire"
-	ctypes "github.com/tendermint/tendermint/rpc/core/types"
-	rpcclient "github.com/tendermint/tendermint/rpc/core_client"
-	"github.com/tendermint/tendermint/types"
 	"time"
 
-	"io/ioutil"
+	. "github.com/tendermint/tendermint/common"
+	"github.com/tendermint/tendermint/rpc/client"
+	ctypes "github.com/tendermint/tendermint/rpc/core/types"
+	core "github.com/tendermint/tendermint/rpc/core_client"
+	"github.com/tendermint/tendermint/rpc/types"
+	"github.com/tendermint/tendermint/types"
+	"github.com/tendermint/tendermint/wire"
 )
 
 const (
@@ -58,14 +60,14 @@ func (n *Node) SetInfo(status *ctypes.ResponseStatus, netinfo *ctypes.ResponseNe
 
 // A node client is used to talk to a node over rpc and websockets
 type NodeClient struct {
-	rpc rpcclient.Client
+	rpc core.Client
 	ws  *rpcclient.WSClient
 }
 
 // Create a new client for the node at the given addr
 func NewNodeClient(addr string) *NodeClient {
 	return &NodeClient{
-		rpc: rpcclient.NewClient("http://"+addr, "JSONRPC"),
+		rpc: core.NewClient("http://"+addr, "JSONRPC"),
 		ws:  rpcclient.NewWSClient("ws://" + addr + "/events"),
 	}
 }
@@ -90,6 +92,8 @@ func (ni nodeInfo) unpack() (string, uint16, string, bool, bool) {
 // A crawler has a local node, a set of potential nodes in the nodePool, and connected nodes.
 // Maps are only accessed by one go-routine, mediated by the checkQueue
 type Crawler struct {
+	QuitService
+
 	self   *Node
 	client *NodeClient
 
@@ -98,22 +102,22 @@ type Crawler struct {
 	nodes      map[string]*Node
 
 	nodeQueue chan *Node
-	quit      chan struct{}
 }
 
 // Create a new Crawler using the local RPC server at addr
 func NewCrawler(host string, port uint16) *Crawler {
-	return &Crawler{
+	crawler := &Crawler{
 		self:       &Node{Host: host, RPCPort: port, client: NewNodeClient(fmt.Sprintf("%s:%d", host, port))},
 		checkQueue: make(chan nodeInfo, CheckQueueBufferSize),
 		nodePool:   make(map[string]*Node),
 		nodes:      make(map[string]*Node),
 		nodeQueue:  make(chan *Node, NodeQueueBufferSize),
-		quit:       make(chan struct{}),
 	}
+	crawler.QuitService = *NewQuitService(log, "Crawler", crawler)
+	return crawler
 }
 
-func (c *Crawler) Start() error {
+func (c *Crawler) OnStart() error {
 	// connect to local node first, set info,
 	// and fire peers onto the checkQueue
 	if err := c.pollNode(c.self); err != nil {
@@ -122,10 +126,8 @@ func (c *Crawler) Start() error {
 
 	// connect to weboscket, subscribe to local events
 	// and run the read loop to listen for new blocks
-	if r, err := c.self.client.ws.Dial(); err != nil {
-		fmt.Println(r)
-		b, _ := ioutil.ReadAll(r.Body)
-		fmt.Println(string(b))
+	_, err := c.self.client.ws.Start()
+	if err != nil {
 		return err
 	}
 	if err := c.self.client.ws.Subscribe(types.EventStringNewBlock()); err != nil {
@@ -147,20 +149,16 @@ func (c *Crawler) Start() error {
 	return nil
 }
 
-func (c *Crawler) Stop() {
-	close(c.quit)
-}
-
 // listen for events from the node and ping it for peers on a ticker
 func (c *Crawler) readLoop(node *Node) {
-	wsChan := node.client.ws.Read()
+	eventsCh := node.client.ws.EventsCh
 	getPeersTicker := time.Tick(time.Second * GetPeersTickerSeconds)
 
 	for {
 		select {
-		case wsMsg := <-wsChan:
+		case eventMsg := <-eventsCh:
 			// update the node with his new info
-			if err := c.consumeMessage(wsMsg, node); err != nil {
+			if err := c.consumeMessage(eventMsg, node); err != nil {
 				// lost the node, put him back on the checkQueu
 				c.checkNode(nodeInfo{
 					host:         node.Host,
@@ -178,37 +176,21 @@ func (c *Crawler) readLoop(node *Node) {
 					disconnected: true,
 				})
 			}
-		case <-c.quit:
+		case <-c.Quit:
 			return
 
 		}
 	}
 }
 
-func (c *Crawler) consumeMessage(wsMsg *rpcclient.WSMsg, node *Node) error {
-	if wsMsg.Error != nil {
-		return wsMsg.Error
-	}
-	// unmarshal block event
-	var response struct {
-		Event string
-		Data  *types.Block
-		Error string
-	}
+func (c *Crawler) consumeMessage(eventMsg rpctypes.RPCEventResult, node *Node) error {
+	var block *types.Block
 	var err error
-	wire.ReadJSON(&response, wsMsg.Data, &err)
-	if err != nil {
-		return err
-	}
-	if response.Error != "" {
-		return fmt.Errorf(response.Error)
-	}
-	block := response.Data
+	wire.ReadJSONObject(block, eventMsg.Data, &err)
 
 	node.LastSeen = time.Now()
 	node.BlockHeight = block.Height
 	node.BlockHistory[block.Height] = node.LastSeen
-
 	return nil
 }
 
@@ -251,7 +233,7 @@ func (c *Crawler) checkLoop() {
 			// queue it for connecting to
 			c.nodeQueue <- n
 
-		case <-c.quit:
+		case <-c.Quit:
 			return
 		}
 	}
@@ -263,7 +245,7 @@ func (c *Crawler) connectLoop() {
 		select {
 		case node := <-c.nodeQueue:
 			go c.connectToNode(node)
-		case <-c.quit:
+		case <-c.Quit:
 			// close all connections
 			for addr, node := range c.nodes {
 				_, _ = addr, node
@@ -278,9 +260,9 @@ func (c *Crawler) connectToNode(node *Node) {
 
 	addr := node.Address()
 	node.client = NewNodeClient(addr)
-
-	if b, err := node.client.ws.Dial(); err != nil {
-		fmt.Println("err on ws dial:", b, err)
+	_, err := node.client.ws.Start()
+	if err != nil {
+		fmt.Println("err on ws start:", err)
 		//  set failed, return
 	}
 
diff --git a/crawler/log.go b/crawler/log.go
new file mode 100644
index 000000000..77b9bdfa8
--- /dev/null
+++ b/crawler/log.go
@@ -0,0 +1,7 @@
+package crawler
+
+import (
+	"github.com/tendermint/tendermint/Godeps/_workspace/src/github.com/tendermint/log15"
+)
+
+var log = log15.New("module", "crawler")
diff --git a/events/events.go b/events/events.go
index 4db658236..25fc7b335 100644
--- a/events/events.go
+++ b/events/events.go
@@ -31,10 +31,11 @@ func NewEventSwitch() *EventSwitch {
 	return evsw
 }
 
-func (evsw *EventSwitch) OnStart() {
+func (evsw *EventSwitch) OnStart() error {
 	evsw.BaseService.OnStart()
 	evsw.eventCells = make(map[string]*eventCell)
 	evsw.listeners = make(map[string]*eventListener)
+	return nil
 }
 
 func (evsw *EventSwitch) OnStop() {
diff --git a/mempool/reactor.go b/mempool/reactor.go
index 2633648ca..4f99c4494 100644
--- a/mempool/reactor.go
+++ b/mempool/reactor.go
@@ -5,11 +5,11 @@ import (
 	"fmt"
 	"reflect"
 
-	"github.com/tendermint/tendermint/wire"
 	. "github.com/tendermint/tendermint/common"
 	"github.com/tendermint/tendermint/events"
 	"github.com/tendermint/tendermint/p2p"
 	"github.com/tendermint/tendermint/types"
+	"github.com/tendermint/tendermint/wire"
 )
 
 var (
@@ -34,10 +34,6 @@ func NewMempoolReactor(mempool *Mempool) *MempoolReactor {
 	return memR
 }
 
-// func (memR *MempoolReactor) OnStart() { memR.BaseReactor.OnStart() }
-
-// func (memR *MempoolReactor) OnStop() { memR.BaseReactor.OnStop() }
-
 // Implements Reactor
 func (memR *MempoolReactor) GetChannels() []*p2p.ChannelDescriptor {
 	return []*p2p.ChannelDescriptor{
diff --git a/node/node.go b/node/node.go
index 39b6e378f..5c7358b6e 100644
--- a/node/node.go
+++ b/node/node.go
@@ -11,7 +11,6 @@ import (
 	"time"
 
 	acm "github.com/tendermint/tendermint/account"
-	"github.com/tendermint/tendermint/wire"
 	bc "github.com/tendermint/tendermint/blockchain"
 	. "github.com/tendermint/tendermint/common"
 	"github.com/tendermint/tendermint/consensus"
@@ -23,6 +22,7 @@ import (
 	"github.com/tendermint/tendermint/rpc/server"
 	sm "github.com/tendermint/tendermint/state"
 	"github.com/tendermint/tendermint/types"
+	"github.com/tendermint/tendermint/wire"
 )
 
 import _ "net/http/pprof"
@@ -141,11 +141,12 @@ func NewNode() *Node {
 }
 
 // Call Start() after adding the listeners.
-func (n *Node) Start() {
+func (n *Node) Start() error {
 	n.book.Start()
 	n.sw.SetNodeInfo(makeNodeInfo(n.sw, n.privKey))
 	n.sw.SetNodePrivKey(n.privKey)
 	n.sw.Start()
+	return nil
 }
 
 func (n *Node) Stop() {
diff --git a/p2p/addrbook.go b/p2p/addrbook.go
index bce9c9c43..9e2447510 100644
--- a/p2p/addrbook.go
+++ b/p2p/addrbook.go
@@ -121,11 +121,12 @@ func (a *AddrBook) init() {
 	}
 }
 
-func (a *AddrBook) OnStart() {
+func (a *AddrBook) OnStart() error {
 	a.QuitService.OnStart()
 	a.loadFromFile(a.filePath)
 	a.wg.Add(1)
 	go a.saveRoutine()
+	return nil
 }
 
 func (a *AddrBook) OnStop() {
diff --git a/p2p/connection.go b/p2p/connection.go
index 6d3591de3..83bafa978 100644
--- a/p2p/connection.go
+++ b/p2p/connection.go
@@ -11,8 +11,8 @@ import (
 	"time"
 
 	flow "github.com/tendermint/tendermint/Godeps/_workspace/src/code.google.com/p/mxk/go1/flowcontrol"
-	"github.com/tendermint/tendermint/wire" //"github.com/tendermint/log15"
 	. "github.com/tendermint/tendermint/common"
+	"github.com/tendermint/tendermint/wire" //"github.com/tendermint/log15"
 )
 
 const (
@@ -127,7 +127,7 @@ func NewMConnection(conn net.Conn, chDescs []*ChannelDescriptor, onReceive recei
 	return mconn
 }
 
-func (c *MConnection) OnStart() {
+func (c *MConnection) OnStart() error {
 	c.BaseService.OnStart()
 	c.quit = make(chan struct{})
 	c.flushTimer = NewThrottleTimer("flush", flushThrottleMS*time.Millisecond)
@@ -135,6 +135,7 @@ func (c *MConnection) OnStart() {
 	c.chStatsTimer = NewRepeatTimer("chStats", updateStatsSeconds*time.Second)
 	go c.sendRoutine()
 	go c.recvRoutine()
+	return nil
 }
 
 func (c *MConnection) OnStop() {
diff --git a/p2p/listener.go b/p2p/listener.go
index dcbaddac9..6a62f9bac 100644
--- a/p2p/listener.go
+++ b/p2p/listener.go
@@ -108,9 +108,10 @@ SKIP_UPNP:
 	return dl
 }
 
-func (l *DefaultListener) OnStart() {
+func (l *DefaultListener) OnStart() error {
 	l.BaseService.OnStart()
 	go l.listenRoutine()
+	return nil
 }
 
 func (l *DefaultListener) OnStop() {
diff --git a/p2p/peer.go b/p2p/peer.go
index c1f12db5d..711a4fe19 100644
--- a/p2p/peer.go
+++ b/p2p/peer.go
@@ -5,9 +5,9 @@ import (
 	"io"
 	"net"
 
-	"github.com/tendermint/tendermint/wire"
 	. "github.com/tendermint/tendermint/common"
 	"github.com/tendermint/tendermint/types"
+	"github.com/tendermint/tendermint/wire"
 )
 
 type Peer struct {
@@ -72,9 +72,10 @@ func newPeer(conn net.Conn, peerNodeInfo *types.NodeInfo, outbound bool, reactor
 	return p
 }
 
-func (p *Peer) OnStart() {
+func (p *Peer) OnStart() error {
 	p.BaseService.OnStart()
-	p.mconn.Start()
+	_, err := p.mconn.Start()
+	return err
 }
 
 func (p *Peer) OnStop() {
diff --git a/p2p/pex_reactor.go b/p2p/pex_reactor.go
index 0f298d9b9..cce7cc1d6 100644
--- a/p2p/pex_reactor.go
+++ b/p2p/pex_reactor.go
@@ -8,9 +8,9 @@ import (
 	"reflect"
 	"time"
 
-	"github.com/tendermint/tendermint/wire"
 	. "github.com/tendermint/tendermint/common"
 	"github.com/tendermint/tendermint/events"
+	"github.com/tendermint/tendermint/wire"
 )
 
 var pexErrInvalidMessage = errors.New("Invalid PEX message")
@@ -41,9 +41,10 @@ func NewPEXReactor(book *AddrBook) *PEXReactor {
 	return pexR
 }
 
-func (pexR *PEXReactor) OnStart() {
+func (pexR *PEXReactor) OnStart() error {
 	pexR.BaseReactor.OnStart()
 	go pexR.ensurePeersRoutine()
+	return nil
 }
 
 func (pexR *PEXReactor) OnStop() {
diff --git a/p2p/switch.go b/p2p/switch.go
index ca2f51a15..111060362 100644
--- a/p2p/switch.go
+++ b/p2p/switch.go
@@ -153,7 +153,7 @@ func (sw *Switch) SetNodePrivKey(nodePrivKey acm.PrivKeyEd25519) {
 }
 
 // Switch.Start() starts all the reactors, peers, and listeners.
-func (sw *Switch) OnStart() {
+func (sw *Switch) OnStart() error {
 	sw.BaseService.OnStart()
 	// Start reactors
 	for _, reactor := range sw.reactors {
@@ -167,6 +167,7 @@ func (sw *Switch) OnStart() {
 	for _, listener := range sw.listeners {
 		go sw.listenerRoutine(listener)
 	}
+	return nil
 }
 
 func (sw *Switch) OnStop() {
diff --git a/rpc/client/ws_client.go b/rpc/client/ws_client.go
index 6480ac96a..85f35df2d 100644
--- a/rpc/client/ws_client.go
+++ b/rpc/client/ws_client.go
@@ -16,31 +16,44 @@ const wsResponsesChannelCapacity = 10
 
 type WSClient struct {
 	QuitService
+	Address string
 	*websocket.Conn
 	EventsCh    chan rpctypes.RPCEventResult
 	ResponsesCh chan rpctypes.RPCResponse
 }
 
 // create a new connection
-func NewWSClient(addr string) (*WSClient, error) {
-	dialer := websocket.DefaultDialer
-	rHeader := http.Header{}
-	con, _, err := dialer.Dial(addr, rHeader)
-	if err != nil {
-		return nil, err
-	}
+func NewWSClient(addr string) *WSClient {
 	wsClient := &WSClient{
-		Conn:        con,
+		Address:     addr,
+		Conn:        nil,
 		EventsCh:    make(chan rpctypes.RPCEventResult, wsEventsChannelCapacity),
 		ResponsesCh: make(chan rpctypes.RPCResponse, wsResponsesChannelCapacity),
 	}
 	wsClient.QuitService = *NewQuitService(log, "WSClient", wsClient)
-	return wsClient, nil
+	return wsClient
 }
 
-func (wsc *WSClient) OnStart() {
+func (wsc *WSClient) OnStart() error {
 	wsc.QuitService.OnStart()
+	err := wsc.dial()
+	if err != nil {
+		return err
+	}
 	go wsc.receiveEventsRoutine()
+	return nil
+}
+
+func (wsc *WSClient) dial() error {
+	// Dial
+	dialer := websocket.DefaultDialer
+	rHeader := http.Header{}
+	con, _, err := dialer.Dial(wsc.Address, rHeader)
+	if err != nil {
+		return err
+	}
+	wsc.Conn = con
+	return nil
 }
 
 func (wsc *WSClient) OnStop() {
diff --git a/rpc/server/handlers.go b/rpc/server/handlers.go
index 153b778fa..16942facf 100644
--- a/rpc/server/handlers.go
+++ b/rpc/server/handlers.go
@@ -240,7 +240,7 @@ func NewWSConnection(baseConn *websocket.Conn, funcMap map[string]*RPCFunc, evsw
 }
 
 // wsc.Start() blocks until the connection closes.
-func (wsc *WSConnection) OnStart() {
+func (wsc *WSConnection) OnStart() error {
 	wsc.QuitService.OnStart()
 
 	// Read subscriptions/unsubscriptions to events
@@ -262,6 +262,7 @@ func (wsc *WSConnection) OnStart() {
 
 	// Write responses, BLOCKING.
 	wsc.writeRoutine()
+	return nil
 }
 
 func (wsc *WSConnection) OnStop() {