// create TCP/IP socket $serverSocket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP); if ($serverSocket === false) { die("Failed to create socket: " . socket_strerror(socket_last_error())); } // bind socket to local address and port $bindResult = socket_bind($serverSocket, '127.0.0.1', 8080); if ($bindResult === false) { die("Failed to bind socket: " . socket_strerror(socket_last_error($serverSocket))); } // listen for incoming connections $listenResult = socket_listen($serverSocket); if ($listenResult === false) { die("Failed to listen on socket: " . socket_strerror(socket_last_error($serverSocket))); } // accept incoming connection and return client socket $clientSocket = socket_accept($serverSocket); if ($clientSocket === false) { die("Failed to accept client connection: " . socket_strerror(socket_last_error($serverSocket))); } // receive data from client socket $data = socket_read($clientSocket, 1024); echo $data; // send data back to client socket $message = "Hello, client!"; $sendResult = socket_write($clientSocket, $message, strlen($message)); if ($sendResult === false) { echo "Failed to send message: " . socket_strerror(socket_last_error($clientSocket)); } // close sockets socket_close($clientSocket); socket_close($serverSocket);This code creates a TCP/IP socket using the `socket_create()` function, binds it to the local address and port using `socket_bind()`, listens for incoming connections using `socket_listen()`, and accepts the first incoming connection using `socket_accept()`. It then reads data from the client socket using `socket_read()`, sends a message back using `socket_write()`, and closes both sockets using `socket_close()`. There is no clear package library associated with this code, as it uses the built-in PHP socket functions. However, there are several third-party socket libraries available for PHP, such as ReactPHP and Socket.io. These libraries provide additional features and abstractions for working with sockets in PHP.