diff --git a/client/pool.go b/client/pool.go
index d0f00cd..86dc67f 100644
--- a/client/pool.go
+++ b/client/pool.go
@@ -6,55 +6,142 @@
 package client
 
 import (
+    "time"
+    "errors"
+    "math/rand"
+    "github.com/mikespook/gearman-go/common"
+)
+
+const (
+    PoolSize = 10
+    DefaultRetry = 5
+)
+
+var (
+    ErrTooMany = errors.New("Too many errors occurred.")
 )
 
 type poolItem struct {
-
+    *Client
+    Rate int
+    Addr string
+}
+
+func (item *poolItem) connect(pool *Pool) (err error) {
+    item.Client, err = New(item.Addr);
+    item.ErrHandler = pool.ErrHandler
+    item.JobHandler = pool.JobHandler
+    item.StatusHandler = pool.StatusHandler
+    item.TimeOut = pool.TimeOut
+    return
+}
+
+
+type SelectionHandler func(map[string]*poolItem, string) string
+
+func SelectWithRate(pool map[string]*poolItem,
+last string) (addr string) {
+    total := 0
+    for _, item := range pool {
+        total += item.Rate
+        if rand.Intn(total) < item.Rate {
+            return item.Addr
+        }
+    }
+    return last
+}
+
+func SelectRandom(pool map[string]*poolItem,
+last string) (addr string) {
+    r := rand.Intn(len(pool))
+    i := 0
+    for k, _ := range pool {
+        if r == i {
+            return k
+        }
+        i ++
+    }
+    return last
 }
 
-/* 
-The client pool
 
-usage:
-pool := client.NewPool()
-pool.Add("127.0.0.1:4730", 1)
-handle := pool.Do("ToUpper", []byte("abcdef"), JOB_LOW|JOB_BG)
 
-*/
 type Pool struct {
+    SelectionHandler SelectionHandler
+    ErrHandler common.ErrorHandler
+    JobHandler JobHandler
+    StatusHandler StatusHandler
+    TimeOut time.Duration
+    Retry int
+
+    items map[string]*poolItem
+    last string
+    handles map[string]string
 }
 
-// Create a new client.
-// Connect to "addr" through "network"
-// Eg.
-//      client, err := client.New("127.0.0.1:4730")
+// Create a new pool.
 func NewPool() (pool *Pool) {
+    return &Pool{
+        items: make(map[string]*poolItem, PoolSize),
+        Retry: DefaultRetry,
+        SelectionHandler: SelectWithRate,
+    }
 }
 
+// Add a server with rate.
 func (pool *Pool) Add(addr string, rate int) {
-    // init a poolItem with Client & rate
+    var item *poolItem
+    var ok bool
+    if item, ok = pool.items[addr]; ok {
+        item.Rate = rate
+    } else {
+        item = &poolItem{Rate: rate, Addr: addr}
+        item.connect(pool)
+        pool.items[addr] = item
+    }
 }
 
-// Do the function.
-// funcname is a string with function name.
-// data is encoding to byte array.
-// flag set the job type, include running level: JOB_LOW, JOB_NORMAL, JOB_HIGH,
-// and if it is background job: JOB_BG.
-// JOB_LOW | JOB_BG means the job is running with low level in background.
-func (pool *Pool) Do(funcname string, data []byte, flag byte) (handle string, err error) {
-    // Select a job server
+func (pool *Pool) Do(funcname string, data []byte,
+flag byte) (addr, handle string, err error) {
+    for i := 0; i < pool.Retry; i ++ {
+        addr = pool.SelectionHandler(pool.items, pool.last)
+        item, ok := pool.items[addr]
+        if ok {
+            pool.last = addr
+            handle, err = item.Do(funcname, data, flag)
+            // error handling
+            // mapping the handle to the server
+            return
+        }
+    }
+    err = ErrTooMany
+    return
 }
 
 // Get job status from job server.
 // !!!Not fully tested.!!!
-func (pool *Pool) Status(handle string) {
-    //
+func (pool *Pool) Status(addr, handle string) {
+    if item, ok := pool.items[addr]; ok {
+        item.Status(handle)
+    }
 }
 
 // Send a something out, get the samething back.
 func (pool *Pool) Echo(data []byte) {
+    for i := 0; i < pool.Retry; i ++ {
+        addr = pool.SelectionHandler(pool.items, pool.last)
+        item, ok := pool.items[addr]
+        if ok {
+            pool.last = addr
+            item.Echo(data)
+        }
+    }
 }
 
 // Close
-func (client *Client) Close() (err error) {
+func (pool *Pool) Close() (err error) {
+    for _, c := range pool.items {
+        err = c.Close()
+    }
+    return
 }