diff --git a/.travis.yml b/.travis.yml
index d897dd8..b20dfe6 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,4 +1,7 @@
 language: go
+go:
   - 1.2
+
 before_install:
-  - sudo apt-get install -qq gearman-job-server
+  - sudo apt-get remove -y gearman-job-server
+  - sudo apt-get install -y gearman-job-server
diff --git a/example/worker/worker b/example/worker/worker
deleted file mode 100755
index c2c9df5..0000000
Binary files a/example/worker/worker and /dev/null differ
diff --git a/worker/agent.go b/worker/agent.go
index a260084..22f8781 100644
--- a/worker/agent.go
+++ b/worker/agent.go
@@ -3,10 +3,12 @@ package worker
 import (
 	"io"
 	"net"
+	"sync"
 )
 
 // The agent of job server.
 type agent struct {
+	sync.Mutex
 	conn      net.Conn
 	worker    *Worker
 	in        chan []byte
@@ -25,6 +27,8 @@ func newAgent(net, addr string, worker *Worker) (a *agent, err error) {
 }
 
 func (a *agent) Connect() (err error) {
+	a.Lock()
+	defer a.Unlock()
 	a.conn, err = net.Dial(a.net, a.addr)
 	if err != nil {
 		return
@@ -40,11 +44,18 @@ func (a *agent) work() {
 	var data, leftdata []byte
 	for {
 		if data, err = a.read(BUFFER_SIZE); err != nil {
-			if err == ErrConnClosed {
+			a.worker.err(err)
+			if err == ErrLostConn {
+				break
+			}
+			// If it is unexpected error and the connection wasn't
+			// closed by Gearmand, the agent should colse the conection
+			// and reconnect to job server.
+			a.conn, err = net.Dial(a.net, a.addr)
+			if err != nil {
+				a.worker.err(err)
 				break
 			}
-			a.worker.err(err)
-			continue
 		}
 		if len(leftdata) > 0 { // some data left for processing
 			data = append(leftdata, data...)
@@ -67,16 +78,25 @@ func (a *agent) work() {
 }
 
 func (a *agent) Close() {
-	a.conn.Close()
+	a.Lock()
+	defer a.Unlock()
+	if a.conn != nil {
+		a.conn.Close()
+		a.conn = nil
+	}
 }
 
 func (a *agent) Grab() {
+	a.Lock()
+	defer a.Unlock()
 	outpack := getOutPack()
 	outpack.dataType = GRAB_JOB_UNIQ
 	a.write(outpack)
 }
 
 func (a *agent) PreSleep() {
+	a.Lock()
+	defer a.Unlock()
 	outpack := getOutPack()
 	outpack.dataType = PRE_SLEEP
 	a.write(outpack)
@@ -89,12 +109,8 @@ func (a *agent) read(length int) (data []byte, err error) {
 	// read until data can be unpacked
 	for i := length; i > 0 || len(data) < MIN_PACKET_LEN; i -= n {
 		if n, err = a.conn.Read(buf); err != nil {
-			if err == io.EOF && n == 0 {
-				if data == nil {
-					err = ErrConnection
-				} else {
-					err = ErrConnClosed
-				}
+			if err == io.EOF {
+				err = ErrLostConn
 			}
 			return
 		}
diff --git a/worker/error.go b/worker/error.go
index 3e2ae7f..ceade3e 100644
--- a/worker/error.go
+++ b/worker/error.go
@@ -7,20 +7,11 @@ import (
 )
 
 var (
-	ErrJobTimeOut    = errors.New("Do a job time out")
-	ErrInvalidData   = errors.New("Invalid data")
-	ErrWorkWarning   = errors.New("Work warning")
-	ErrWorkFail      = errors.New("Work fail")
-	ErrWorkException = errors.New("Work exeption")
-	ErrDataType      = errors.New("Invalid data type")
-	ErrOutOfCap      = errors.New("Out of the capability")
-	ErrNotConn       = errors.New("Did not connect to job server")
-	ErrFuncNotFound  = errors.New("The function was not found")
-	ErrConnection    = errors.New("Connection error")
-	ErrNoActiveAgent = errors.New("No active agent")
-	ErrTimeOut       = errors.New("Executing time out")
-	ErrUnknown       = errors.New("Unknown error")
-	ErrConnClosed    = errors.New("Connection closed")
+	ErrNoneAgents = errors.New("None active agents")
+	ErrNoneFuncs  = errors.New("None functions")
+	ErrTimeOut    = errors.New("Executing time out")
+	ErrUnknown    = errors.New("Unknown error")
+	ErrLostConn   = errors.New("Lost connection with Gearmand")
 )
 
 // Extract the error message
diff --git a/worker/example_test.go b/worker/example_test.go
new file mode 100644
index 0000000..f317783
--- /dev/null
+++ b/worker/example_test.go
@@ -0,0 +1,57 @@
+package worker_test
+
+import (
+	"fmt"
+	"github.com/mikespook/gearman-go/worker"
+	"sync"
+)
+
+func ExampleWorker() {
+	// An example of worker
+	w := worker.New(worker.Unlimited)
+	defer w.Close()
+	// Add a gearman job server
+	if err := w.AddServer("tcp4", "127.0.0.1:4730"); err != nil {
+		fmt.Println(err)
+		return
+	}
+	// A function for handling jobs
+	foobar := func(job worker.Job) ([]byte, error) {
+		// Do nothing here
+		return nil, nil
+	}
+	// Add the function to worker
+	if err := w.AddFunc("foobar", foobar, 0); err != nil {
+		fmt.Println(err)
+		return
+	}
+	var wg sync.WaitGroup
+	// A custome handler, for handling other results, eg. ECHO, ERROR.
+	w.JobHandler = func(job worker.Job) error {
+		if job.Err() == nil {
+			fmt.Println(string(job.Data()))
+		} else {
+			fmt.Println(job.Err())
+		}
+		wg.Done()
+		return nil
+	}
+	// An error handler for handling worker's internal errors.
+	w.ErrorHandler = func(e error) {
+		fmt.Println(e)
+		// Ignore the error or shutdown the worker
+	}
+	// Tell Gearman job server: I'm ready!
+	if err := w.Ready(); err != nil {
+		fmt.Println(err)
+		return
+	}
+	// Running main loop
+	go w.Work()
+	wg.Add(1)
+	// calling Echo
+	w.Echo([]byte("Hello"))
+	// Waiting results
+	wg.Wait()
+	// Output: Hello
+}
diff --git a/worker/inpack.go b/worker/inpack.go
index b00996b..c6edc9c 100644
--- a/worker/inpack.go
+++ b/worker/inpack.go
@@ -24,6 +24,13 @@ func (inpack *inPack) Data() []byte {
 	return inpack.data
 }
 
+func (inpack *inPack) Err() error {
+	if inpack.dataType == ERROR {
+		return GetError(inpack.data)
+	}
+	return nil
+}
+
 // Send some datas to client.
 // Using this in a job's executing.
 func (inpack *inPack) SendData(data []byte) {
diff --git a/worker/job.go b/worker/job.go
index 4f9950a..d2d7d6f 100644
--- a/worker/job.go
+++ b/worker/job.go
@@ -1,6 +1,7 @@
 package worker
 
 type Job interface {
+	Err() error
 	Data() []byte
 	SendWarning(data []byte)
 	SendData(data []byte)
diff --git a/worker/worker.go b/worker/worker.go
index bbc7c5c..478f00f 100644
--- a/worker/worker.go
+++ b/worker/worker.go
@@ -10,10 +10,10 @@ import (
 )
 
 const (
-	Unlimited = 0
-	OneByOne  = 1
+	Unlimited = iota
+	OneByOne
 
-	Immediately = 0
+	Immediately = iota
 )
 
 // Worker is the only structure needed by worker side developing.
@@ -139,8 +139,6 @@ func (worker *Worker) handleInPack(inpack *inPack) {
 		inpack.a.PreSleep()
 	case NOOP:
 		inpack.a.Grab()
-	case ERROR:
-		worker.err(GetError(inpack.data))
 	case JOB_ASSIGN, JOB_ASSIGN_UNIQ:
 		go func() {
 			if err := worker.exec(inpack); err != nil {
@@ -151,6 +149,9 @@ func (worker *Worker) handleInPack(inpack *inPack) {
 			worker.limit <- true
 		}
 		inpack.a.Grab()
+	case ERROR:
+		worker.err(inpack.Err())
+		fallthrough
 	case ECHO_RES:
 		fallthrough
 	default:
@@ -161,6 +162,12 @@ func (worker *Worker) handleInPack(inpack *inPack) {
 // Connect to Gearman server and tell every server
 // what can this worker do.
 func (worker *Worker) Ready() (err error) {
+	if len(worker.agents) == 0 {
+		return ErrNoneAgents
+	}
+	if len(worker.funcs) == 0 {
+		return ErrNoneFuncs
+	}
 	for _, v := range worker.agents {
 		if err = v.Connect(); err != nil {
 			return
@@ -201,8 +208,12 @@ func (worker *Worker) customeHandler(inpack *inPack) {
 
 // Close connection and exit main loop
 func (worker *Worker) Close() {
-	worker.running = false
-	close(worker.in)
+	worker.Lock()
+	worker.Unlock()
+	if worker.running == true {
+		worker.running = false
+		close(worker.in)
+	}
 }
 
 // Echo
diff --git a/worker/worker_test.go b/worker/worker_test.go
index bb0666c..b76e6b9 100644
--- a/worker/worker_test.go
+++ b/worker/worker_test.go
@@ -11,6 +11,13 @@ func init() {
 	worker = New(Unlimited)
 }
 
+func TestWorkerErrNoneAgents(t *testing.T) {
+	err := worker.Ready()
+	if err != ErrNoneAgents {
+		t.Error("ErrNoneAgents expected.")
+	}
+}
+
 func TestWorkerAddServer(t *testing.T) {
 	t.Log("Add local server 127.0.0.1:4730.")
 	if err := worker.AddServer("tcp4", "127.0.0.1:4730"); err != nil {
@@ -23,6 +30,13 @@ func TestWorkerAddServer(t *testing.T) {
 	}
 }
 
+func TestWorkerErrNoneFuncs(t *testing.T) {
+	err := worker.Ready()
+	if err != ErrNoneFuncs {
+		t.Error("ErrNoneFuncs expected.")
+	}
+}
+
 func foobar(job Job) ([]byte, error) {
 	return nil, nil
 }