diff --git a/.gitignore b/.gitignore
index 259148f..c9c2869 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,5 @@
+.vscode/
+
 # Prerequisites
 *.d
 
diff --git a/csmodel/cppexample/client.cpp b/csmodel/cppexample/client.cpp
new file mode 100644
index 0000000..8427c3f
--- /dev/null
+++ b/csmodel/cppexample/client.cpp
@@ -0,0 +1,81 @@
+#include <iostream>
+#include <string>
+#include <stdio.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <netdb.h>
+#include <sys/uio.h>
+#include <sys/time.h>
+#include <sys/wait.h>
+#include <fcntl.h>
+#include <fstream>
+using namespace std;
+//Client side
+int main(int argc, char *argv[])
+{
+    //we need 2 things: ip address and port number, in that order
+    if(argc != 3)
+    {
+        cerr << "Usage: ip_address port" << endl; exit(0); 
+    } //grab the IP address and port number 
+    char *serverIp = argv[1]; int port = atoi(argv[2]); 
+    //create a message buffer 
+    char msg[1500]; 
+    //setup a socket and connection tools 
+    struct hostent* host = gethostbyname(serverIp); 
+    sockaddr_in sendSockAddr;   
+    bzero((char*)&sendSockAddr, sizeof(sendSockAddr)); 
+    sendSockAddr.sin_family = AF_INET; 
+    sendSockAddr.sin_addr.s_addr = 
+        inet_addr(inet_ntoa(*(struct in_addr*)*host->h_addr_list));
+    sendSockAddr.sin_port = htons(port);
+    int clientSd = socket(AF_INET, SOCK_STREAM, 0);
+    //try to connect...
+    int status = connect(clientSd,
+                         (sockaddr*) &sendSockAddr, sizeof(sendSockAddr));
+    if(status < 0)
+    {
+        cout<<"Error connecting to socket!"<<endl;
+    }
+    cout << "Connected to the server!" << endl;
+    int bytesRead, bytesWritten = 0;
+    struct timeval start1, end1;
+    gettimeofday(&start1, NULL);
+    while(1)
+    {
+        cout << ">";
+        string data;
+        getline(cin, data);
+        memset(&msg, 0, sizeof(msg));//clear the buffer
+        strcpy(msg, data.c_str());
+        if(data == "exit")
+        {
+            send(clientSd, (char*)&msg, strlen(msg), 0);
+            break;
+        }
+        bytesWritten += send(clientSd, (char*)&msg, strlen(msg), 0);
+        cout << "Awaiting server response..." << endl;
+        memset(&msg, 0, sizeof(msg));//clear the buffer
+        bytesRead += recv(clientSd, (char*)&msg, sizeof(msg), 0);
+        if(!strcmp(msg, "exit"))
+        {
+            cout << "Server has quit the session" << endl;
+            break;
+        }
+        cout << "Server: " << msg << endl;
+    }
+    gettimeofday(&end1, NULL);
+    close(clientSd);
+    cout << "********Session********" << endl;
+    cout << "Bytes written: " << bytesWritten << 
+    " Bytes read: " << bytesRead << endl;
+    cout << "Elapsed time: " << (end1.tv_sec- start1.tv_sec) 
+      << " secs" << endl;
+    cout << "Connection closed" << endl;
+    return 0;    
+}
\ No newline at end of file
diff --git a/csmodel/cppexample/server.cpp b/csmodel/cppexample/server.cpp
new file mode 100644
index 0000000..88d5d4f
--- /dev/null
+++ b/csmodel/cppexample/server.cpp
@@ -0,0 +1,112 @@
+#include <iostream>
+#include <string>
+#include <stdio.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <netdb.h>
+#include <sys/uio.h>
+#include <sys/time.h>
+#include <sys/wait.h>
+#include <fcntl.h>
+#include <fstream>
+using namespace std;
+//Server side
+int main(int argc, char *argv[])
+{
+    //for the server, we only need to specify a port number
+    if(argc != 2)
+    {
+        cerr << "Usage: port" << endl;
+        exit(0);
+    }
+    //grab the port number
+    int port = atoi(argv[1]);
+    //buffer to send and receive messages with
+    char msg[1500];
+     
+    //setup a socket and connection tools
+    sockaddr_in servAddr;
+    bzero((char*)&servAddr, sizeof(servAddr));
+    servAddr.sin_family = AF_INET;
+    servAddr.sin_addr.s_addr = htonl(INADDR_ANY);
+    servAddr.sin_port = htons(port);
+ 
+    //open stream oriented socket with internet address
+    //also keep track of the socket descriptor
+    int serverSd = socket(AF_INET, SOCK_STREAM, 0);
+    if(serverSd < 0)
+    {
+        cerr << "Error establishing the server socket" << endl;
+        exit(0);
+    }
+    //bind the socket to its local address
+    int bindStatus = bind(serverSd, (struct sockaddr*) &servAddr, 
+        sizeof(servAddr));
+    if(bindStatus < 0)
+    {
+        cerr << "Error binding socket to local address" << endl;
+        exit(0);
+    }
+    cout << "Waiting for a client to connect..." << endl;
+    //listen for up to 5 requests at a time
+    listen(serverSd, 5);
+    //receive a request from client using accept
+    //we need a new address to connect with the client
+    sockaddr_in newSockAddr;
+    socklen_t newSockAddrSize = sizeof(newSockAddr);
+    //accept, create a new socket descriptor to 
+    //handle the new connection with client
+    int newSd = accept(serverSd, (sockaddr *)&newSockAddr, &newSockAddrSize);
+    if(newSd < 0)
+    {
+        cerr << "Error accepting request from client!" << endl;
+        exit(1);
+    }
+    cout << "Connected with client!" << endl;
+    //lets keep track of the session time
+    struct timeval start1, end1;
+    gettimeofday(&start1, NULL);
+    //also keep track of the amount of data sent as well
+    int bytesRead, bytesWritten = 0;
+    while(1)
+    {
+        //receive a message from the client (listen)
+        cout << "Awaiting client response..." << endl;
+        memset(&msg, 0, sizeof(msg));//clear the buffer
+        bytesRead += recv(newSd, (char*)&msg, sizeof(msg), 0);
+        if(!strcmp(msg, "exit"))
+        {
+            cout << "Client has quit the session" << endl;
+            break;
+        }
+        cout << "Client: " << msg << endl;
+        cout << ">";
+        string data;
+        getline(cin, data);
+        memset(&msg, 0, sizeof(msg)); //clear the buffer
+        strcpy(msg, data.c_str());
+        if(data == "exit")
+        {
+            //send to the client that server has closed the connection
+            send(newSd, (char*)&msg, strlen(msg), 0);
+            break;
+        }
+        //send the message to client
+        bytesWritten += send(newSd, (char*)&msg, strlen(msg), 0);
+    }
+    //we need to close the socket descriptors after we're all done
+    gettimeofday(&end1, NULL);
+    close(newSd);
+    close(serverSd);
+    cout << "********Session********" << endl;
+    cout << "Bytes written: " << bytesWritten << " Bytes read: " << bytesRead << endl;
+    cout << "Elapsed time: " << (end1.tv_sec - start1.tv_sec) 
+        << " secs" << endl;
+    cout << "Connection closed..." << endl;
+    return 0;   
+}
\ No newline at end of file
diff --git a/csmodel/echoClient.c b/csmodel/echoClient.c
new file mode 100644
index 0000000..f54ffb3
--- /dev/null
+++ b/csmodel/echoClient.c
@@ -0,0 +1,66 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <string.h>
+#include <unistd.h>
+#include <arpa/inet.h>
+
+#define MAXLINE 4096 /*max text line length*/
+#define SERV_PORT 3000 /*port*/
+
+int
+main(int argc, char **argv) 
+{
+ int sockfd;
+ struct sockaddr_in servaddr;
+ char sendline[MAXLINE], recvline[MAXLINE];
+	
+ //basic check of the arguments
+ //additional checks can be inserted
+ if (argc !=2) {
+  perror("Usage: TCPClient <IP address of the server"); 
+  exit(1);
+ }
+	
+ //Create a socket for the client
+ //If sockfd<0 there was an error in the creation of the socket
+ if ((sockfd = socket (AF_INET, SOCK_STREAM, 0)) <0) {
+  perror("Problem in creating the socket");
+  exit(2);
+ }
+	
+ //Creation of the socket
+ memset(&servaddr, 0, sizeof(servaddr));
+ servaddr.sin_family = AF_INET;
+ servaddr.sin_addr.s_addr = inet_addr(argv[1]);
+ servaddr.sin_port = htons(SERV_PORT); //convert to big-endian order
+	
+ //Connection of the client to the socket 
+ if (connect(sockfd, (struct sockaddr *) &servaddr, sizeof(servaddr))<0) {
+  perror("Problem in connecting to the server");
+  exit(3);
+ }
+ printf("> ");
+
+ while (fgets(sendline, MAXLINE, stdin) != NULL) {
+  if(strstr(sendline, "exit") == sendline)
+  {
+    close(sockfd);
+    break;
+  }
+  send(sockfd, sendline, strlen(sendline), 0);
+  memset(recvline, 0, MAXLINE);
+  if (recv(sockfd, recvline, MAXLINE, 0) == 0){
+   //error: server terminated prematurely
+   perror("The server terminated prematurely"); 
+   exit(4);
+  }
+//   printf("\n", "String received from the server: ");
+//   fputs(recvline, stdout);
+  printf("%s\n> ", recvline);
+ }
+ printf("socket close\n");
+ exit(0);
+}
diff --git a/csmodel/echoServer.c b/csmodel/echoServer.c
new file mode 100644
index 0000000..8890bcd
--- /dev/null
+++ b/csmodel/echoServer.c
@@ -0,0 +1,66 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <string.h>
+#include <unistd.h>
+
+#define MAXLINE 4096 /*max text line length*/
+#define SERV_PORT 3000 /*port*/
+#define LISTENQ 8 /*maximum number of client connections */
+
+int main (int argc, char **argv)
+{
+ int listenfd, connfd, n;
+ pid_t childpid;
+ socklen_t clilen;
+ char buf[MAXLINE];
+ struct sockaddr_in cliaddr, servaddr;
+	
+ //creation of the socket
+ listenfd = socket (AF_INET, SOCK_STREAM, 0);
+	
+ //preparation of the socket address 
+ servaddr.sin_family = AF_INET;
+ servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
+ servaddr.sin_port = htons(SERV_PORT);
+	
+ bind (listenfd, (struct sockaddr *) &servaddr, sizeof(servaddr));
+	
+ listen (listenfd, LISTENQ);
+	
+ printf("%s\n","Server running...waiting for connections.");
+	
+ for ( ; ; ) {
+		
+  clilen = sizeof(cliaddr);
+  connfd = accept (listenfd, (struct sockaddr *) &cliaddr, &clilen);
+  printf("%s\n","Received request...");
+				
+  while ( (n = recv(connfd, buf, MAXLINE, 0)) > 0)  {
+   printf("%s","----- String received from and resent to the client: -----\n");
+   buf[n-1] = 0;
+   puts(buf);
+   printf("%lu\n",strlen(buf));
+   if (strstr(buf, "hello server") == buf){
+    send(connfd, "hello client", 12, 0);
+    continue;
+   }
+   if (strlen(buf) == 0){
+    send(connfd, "?", 2, 0);
+    continue;
+   }
+   send(connfd, buf, n, 0);
+  }
+			
+ if (n < 0) {
+  perror("Read error"); 
+  exit(1);
+ }
+ close(connfd);
+	
+ }
+ //close listening socket
+ close (listenfd); 
+}
diff --git a/socket/client.c b/socket/client.c
new file mode 100644
index 0000000..2774eb2
--- /dev/null
+++ b/socket/client.c
@@ -0,0 +1,62 @@
+// https://www.linuxhowtos.org/C_C++/socket.htm
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <netdb.h> 
+
+void error(const char *msg)
+{
+    perror(msg);
+    exit(0);
+}
+
+int main(int argc, char *argv[])
+{
+    int sockfd, portno, n;
+    struct sockaddr_in serv_addr;
+    struct hostent *server;
+
+    char buffer[256];
+    if (argc < 3) {
+       fprintf(stderr,"usage %s hostname port\n", argv[0]);
+       exit(0);
+    }
+    portno = atoi(argv[2]);
+    sockfd = socket(AF_INET, SOCK_STREAM, 0);
+    if (sockfd < 0) 
+        error("ERROR opening socket");
+    server = gethostbyname(argv[1]);
+    if (server == NULL) {
+        fprintf(stderr,"ERROR, no such host\n");
+        exit(0);
+    }
+    bzero((char *) &serv_addr, sizeof(serv_addr));
+    serv_addr.sin_family = AF_INET;
+    bcopy((char *)server->h_addr, 
+         (char *)&serv_addr.sin_addr.s_addr,
+         server->h_length);
+    serv_addr.sin_port = htons(portno);
+    // 连接端口
+    if (connect(sockfd,(struct sockaddr *) &serv_addr,sizeof(serv_addr)) < 0) 
+        error("ERROR connecting");
+    printf("Please enter the message: ");
+    bzero(buffer,256);
+    fgets(buffer,255,stdin);
+    // 写入数据
+    n = write(sockfd,buffer,strlen(buffer));
+    if (n < 0) 
+         error("ERROR writing to socket");
+    bzero(buffer,256);
+    // 读取数据
+    n = read(sockfd,buffer,255);
+    if (n < 0) 
+         error("ERROR reading from socket");
+    printf("%s\n",buffer);
+    close(sockfd);
+    return 0;
+}
diff --git a/socket/server.c b/socket/server.c
new file mode 100644
index 0000000..947d186
--- /dev/null
+++ b/socket/server.c
@@ -0,0 +1,60 @@
+/* A simple server in the internet domain using TCP
+   The port number is passed as an argument */
+   
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/types.h> 
+#include <sys/socket.h>
+#include <netinet/in.h>
+
+void error(const char *msg)
+{
+    perror(msg);
+    exit(1);
+}
+
+int main(int argc, char *argv[])
+{
+     int sockfd, newsockfd, portno;
+     socklen_t clilen;
+     char buffer[256];
+     struct sockaddr_in serv_addr, cli_addr;
+     int n;
+     if (argc < 2) {
+         fprintf(stderr,"ERROR, no port provided\n");
+         exit(1);
+     }
+     sockfd = socket(AF_INET, SOCK_STREAM, 0);
+     if (sockfd < 0) 
+        error("ERROR opening socket");
+     bzero((char *) &serv_addr, sizeof(serv_addr));
+     portno = atoi(argv[1]);
+     serv_addr.sin_family = AF_INET;
+     serv_addr.sin_addr.s_addr = INADDR_ANY;
+     serv_addr.sin_port = htons(portno);
+     if (bind(sockfd, (struct sockaddr *) &serv_addr,
+              sizeof(serv_addr)) < 0) 
+              error("ERROR on binding");
+     // 监听端口
+     listen(sockfd,5);
+     clilen = sizeof(cli_addr);
+     // 建立连接
+     newsockfd = accept(sockfd, 
+                 (struct sockaddr *) &cli_addr, 
+                 &clilen);
+     if (newsockfd < 0) 
+          error("ERROR on accept");
+     bzero(buffer,256);
+     // 读取数据
+     n = read(newsockfd,buffer,255);
+     if (n < 0) error("ERROR reading from socket");
+     printf("Here is the message: %s\n",buffer);
+     // 写入数据
+     n = write(newsockfd,"I got your message",18);
+     if (n < 0) error("ERROR writing to socket");
+     close(newsockfd);
+     close(sockfd);
+     return 0; 
+}