go語言快速入門 IPC之Socket 9
多進程之間的通信常見的手段有管道/信號量/共享內存/Socket等,在上篇文章中介紹了管道的使用方法。管道在多進程通信中使用方便但是也具局限性,當通信雙方在不同的機器上的時候通信方式更多采用Socket方式。在這篇文章中我們將會繼續探索如何使用go所提供的net包等實現TCP和UDP方式的Socket通信。
傳輸層協議
OSI模型
OSI七層模型,簡單來說,下三層主要負責數據通信,而上三層主要負責數據處理。處於第四層的傳輸層是通信子網和資源子網的接口和橋梁,整體起到承上啟下的作用。而TCP和UDP則是傳輸層的協議。
TCP和UDP的區別
TCP和UDP最大的區別在於是否是面向連接的協議,作為面向連接的TCP協議,以此決定了在本質上是否是安全可靠的特性。
TCP通信
無論TCP方式還是UDP方式,常見的場景應用會分為服務器端和客戶端的類型。作為面向連接的TCP方式,服務器端的應用一般會綁定到某一端口,然後再此端口上進行監聽,當其受到客戶端的連接時便會進行交互。
Server端實現
[root@liumiaocn goprj]# cat basic-tcp-server.go
package main
import "fmt"
import "os"
import "net"
import "time"
func main() {
//get a tcp address
tcp_address, err := net.ResolveTCPAddr("tcp4" , ":8848")
if err != nil {
fmt.Println("Error happened when getting a tcp address...", err)
os.Exit(1)
}
//listen to the tcp address
tcp_listener, err := net.ListenTCP("tcp", tcp_address)
if err != nil {
fmt.Println("Error happened when listening to the tcp address..." , err)
os.Exit(1)
}
//greeting words
str_header := "Hello, this is information from tcp server , and current time is : "
//main loop of tcp server
for {
//waiting connection from client
tcp_connection, err := tcp_listener.Accept()
if err != nil {
continue
}
//get the current time infor
str_time := time.Now().String()
//set greeting words for client connection
str_greetings := str_header + str_time
//send information to client
tcp_connection.Write([]byte(str_greetings))
tcp_connection.Close()
}
}
[root@liumiaocn goprj]#
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客戶端實現
[root@liumiaocn goprj]# cat basic-tcp-client.go
package main
import "fmt"
import "io/ioutil"
import "os"
import "net"
func main() {
//usage of client application
if len(os.Args) != 2 {
fmt.Fprintf(os.Stderr, "Usage: %s host:port ", os.Args[0])
os.Exit(1)
}
//get a tcp address
arg_address := os.Args[1]
tcp_address, err := net.ResolveTCPAddr("tcp4", arg_address)
if err != nil {
fmt.Println("Error happened when getting a tcp address...", err)
os.Exit(1)
}
//connect to a tcp server
tcp_connection, err := net.DialTCP("tcp", nil, tcp_address)
if err != nil {
fmt.Println("Error happened when connecting a tcp server...", err)
os.Exit(1)
}
//read information from tcp server
str_greeting, err := ioutil.ReadAll(tcp_connection)
if err != nil {
fmt.Println("Error happened when reading from the tcp server...", err)
os.Exit(1)
}
//display the information
fmt.Println(string(str_greeting))
os.Exit(0)
}
[root@liumiaocn goprj]#
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執行確認
首先將server端運行起來,等待client端的連接
[root@liumiaocn goprj]# go run basic-tcp-server.go
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運行client端,可以得到從server端發過的信息
[root@liumiaocn goprj]# go run basic-tcp-client.go 192.168.32.123:8848
Hello, this is information from tcp server , and current time is : 2017-01-31 10:56:48.590783817 -0500 EST
[root@liumiaocn goprj]#
[root@liumiaocn goprj]# go run basic-tcp-client.go 192.168.32.123:8848
Hello, this is information from tcp server , and current time is : 2017-01-31 10:56:54.969361975 -0500 EST
[root@liumiaocn goprj]#
[root@liumiaocn goprj]# go run basic-tcp-client.go 192.168.32.123:8848
Hello, this is information from tcp server , and current time is : 2017-01-31 10:57:08.226263371 -0500 EST
[root@liumiaocn goprj]#
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UDP方式
通過上述例子,可以了解到TCP方式的簡單實現。接下來看一下UDP方式。UDP作為無連接的傳輸層協議的實現,在go所提供的API可以看到,形式已經非常類似。
Server端實現
[root@liumiaocn goprj]# cat basic-udp_server.go
package main
import "fmt"
import "os"
import "net"
import "time"
func main() {
//get a udp address
udp_address, err := net.ResolveUDPAddr("udp4", ":9848")
if err != nil {
fmt.Println("Error happened when getting a udp address...", err)
os.Exit(1)
}
//listen to the udp address
udp_connection, err := net.ListenUDP("udp", udp_address)
if err != nil {
fmt.Println("Error happened when listening to the udp address...", err)
os.Exit(1)
}
//greeting words
str_header := "Hello, this is information from udp server , and current time is : "
//main loop of udp server
for {
//read information from client
var udp_buffer [1024]byte
_, address, err := udp_connection.ReadFromUDP(udp_buffer[0:])
if err != nil {
continue
}
//get the current time infor
str_time := time.Now().String()
//set greeting words for client connection
str_greetings := str_header + str_time
//send information to client
udp_connection.WriteToUDP([]byte(str_greetings), address)
}
}
[root@liumiaocn goprj]#
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客戶端實現
[root@liumiaocn goprj]# cat basic-udp_client.go
package main
import "fmt"
import "os"
import "net"
func main() {
//usage of client application
if len(os.Args) != 2 {
fmt.Fprintf(os.Stderr, "Usage: %s host:port ", os.Args[0])
os.Exit(1)
}
//get a udp address
arg_address := os.Args[1]
udp_address, err := net.ResolveUDPAddr("udp4", arg_address)
if err != nil {
fmt.Println("Error happened when getting a udp address...", err)
os.Exit(1)
}
//connect to a udp server
udp_connection, err := net.DialUDP("udp", nil, udp_address)
if err != nil {
fmt.Println("Error happened when connecting a udp server...", err)
os.Exit(1)
}
//send information to udp server
_, err = udp_connection.Write([]byte("hello"))
if err != nil {
fmt.Println("Error happened when sending message to the udp server...", err)
os.Exit(1)
}
//udp buffer
var udp_buffer [1024]byte
//read information from udp server
num, err := udp_connection.Read(udp_buffer[0:])
if err != nil {
fmt.Println("Error happened when reading from the tcp server...", err)
os.Exit(1)
}
//display the information
fmt.Println(string(udp_buffer[0:num]))
os.Exit(0)
}
[root@liumiaocn goprj]#
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執行確認
首先將server端運行起來,等待client端的連接
[root@liumiaocn goprj]# go run basic-udp_server.go
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運行client端,可以得到從server端發過的信息
[root@liumiaocn goprj]# go run basic-udp_client.go 192.168.32.123:9848
Hello, this is information from udp server , and current time is : 2017-01-31 11:25:03.274881649 -0500 EST
[root@liumiaocn goprj]#
[root@liumiaocn goprj]# go run basic-udp_client.go 192.168.32.123:9848
Hello, this is information from udp server , and current time is : 2017-01-31 11:25:05.895074805 -0500 EST
[root@liumiaocn goprj]#
[root@liumiaocn goprj]# go run basic-udp_client.go 192.168.32.123:9848
Hello, this is information from udp server , and current time is : 2017-01-31 11:25:09.886004761 -0500 EST
[root@liumiaocn goprj]#
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總結
在這篇文章中,我們繼續討論了go語言中Socket通信的兩個簡單實例,通過這兩個例子,實現了TCP和UDP的服務器和客戶端的交互。雖然在實際中的應用還有很遠一段距離,比如並發的控制上述簡單的例子沒有涉及到,但是通過這兩個例子,已經能看出多進程通信的go的實現方式。
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go語言快速入門 IPC之Socket 9