Using J2ME I need to send a JPEG image to a server using Socket Communication. Can anyone send me a sample code for my application?
Take a look at this article from Sun Developer Network. It has some minimalistic examples and should give you some ideas.
...
SocketConnection client = (SocketConnection) Connector.open("socket://" + hostname + ":" + port);
// set application-specific options on the socket. Call setSocketOption to set other options
client.setSocketOption(DELAY, 0);
client.setSocketOption(KEEPALIVE, 0);
InputStream is = client.openInputStream();
OutputStream os = client.openOutputStream();
// send something to server
os.write("some string".getBytes());
// read server response
int c = 0;
while((c = is.read()) != -1) {
// do something with the response
}
// close streams and connection
is.close();
os.close();
client.close();
...
Related
I have a hardware that streams data to a windows server, and I have IP and port of this server. Now I want to connect unity app as a TCP client to this server. I have tried many solutions, but still have hard time to figure out best way to do this. Any help is highly appreciated. One issue that I have with current tutorials is that most of them define a unity server and try to connect another unity app as client and mostly based on localhost. However, I just want to connect a unity app as a TCP client to a server which I have IP and port.
Warm regards,
enter image description here
First of all, at the top of your script:
using System;
using System.Net.Sockets;
Then, create an instance of TcpClient and begin the connection:
socket = new TcpClient
{
// dataBufferSize is in bytes
ReceiveBufferSize = dataBufferSize,
SendBufferSize = dataBufferSize
};
socket.BeginConnect(ip, port, ConnectCallback, socket);
In ConnectCallback():
private void ConnectCallback(IAsyncResult asyncResult)
{
socket.EndConnect(asyncResult);
if (!socket.Connected) return;
// stream is a NetworkStream you should declare somewhere
stream = socket.GetStream();
// receiveBuffer is a byte[] you should declare somewhere
receiveBuffer = new byte[dataBufferSize];
stream.BeginRead(receiveBuffer, 0, dataBufferSize, ReceiveCallback, null);
}
In ReceiveCallback():
private void ReceiveCallback(IAsyncResult asyncResult)
{
try
{
int byteLength = stream.EndRead(asyncResult);
if (byteLength <= 0)
{
// Disconnect client
return;
}
// Transfer data from receiveBuffer to data variable for handling
byte[] data = new byte[byteLength];
Array.Copy(receiveBuffer, data, byteLength);
// Handle data in any way you want to
// BeginRead again so you can keep receiving data
stream.BeginRead(receiveBuffer, 0, dataBufferSize, ReceiveCallback, null);
}
catch (Exception e)
{
Console.WriteLine($"Error receiving TCP data: {e.Message}");
}
}
I got this information from this tutorial.
I'm trying to create a REST server on an arduino mkr1000. upon searching google i came upon the aRest library which handles most of the stuff i need.
aRest library documentation
So i created a sample sketch based on the guides. Here is the code:
#include < SPI.h >
#include < WiFi101.h >
#include < aREST.h >
aREST rest = aREST();
int status = WL_IDLE_STATUS;
WiFiServer restServer(80);
char ssid[] = "user"; // not actual username
char pass[] = "pass"; // not actual password
int clapMode(String data){
Serial.println("Request Recieved: " + data);
}
void setup() {
Serial.begin(115200);
rest.set_id("000");
rest.set_name("MKR1000");
rest.function("test",clapMode);
while ( status != WL_CONNECTED) {
Serial.print("Attempting to connect to SSID: ");
Serial.println(ssid);
// Connect to WPA/WPA2 network. Change this line if using open or WEP
network:
status = WiFi.begin(ssid, pass);
// wait 10 seconds for connection:
delay(10000);
}
Serial.println();
// you're connected now, so print out the status:
printWifiStatus();
// Start server
restServer.begin();
Serial.println(F("Listening for connections..."));
}
void loop() {
WiFiClient client = restServer.available();
if (!client) {
return;
}
while(!client.available()){
delay(1);
}
rest.handle(client);
}
void printWifiStatus() {
// print the SSID of the network you're attached to:
Serial.print("SSID: ");
Serial.println(WiFi.SSID());
// print your WiFi shield's IP address:
IPAddress ip = WiFi.localIP();
Serial.print("IP Address: ");
Serial.println(ip);
IPAddress subnet = WiFi.subnetMask();
Serial.print("Netmask: ");
Serial.println(subnet);
IPAddress gateway = WiFi.gatewayIP();
Serial.print("Gateway: ");
Serial.println(gateway);
// print the received signal strength:
long rssi = WiFi.RSSI();
Serial.print("signal strength (RSSI):");
Serial.print(rssi);
Serial.println(" dBm");
}
The code works mostly. Upon using POSTMAN to perform a GET the arduino is able to give the appropriate response.
Now for the part that is not working is the endpoint i just have created using this code
rest.function("test",clapMode);
upon performing a GET in postman, the arduino is able to give a response, but it should perform this code
int clapMode(String data){
Serial.println("Request Recieved: " + data);
}
but on my serial Monitor i am not getting anything.
Also i could not find on how to tailor the response of the arduino from the request. How do i it ?
Thank you very much
You have to send the request to <host>/test?params=0, not <host>/clapMode.
Furthermore, you can modify the ID and name with
rest.set_id("device ID");
rest.set_name("device name");
and add variables with
rest.variable("variable name", &variable);
The response is hard-coded into the library, therefore if you want to add/remove other stuff, you have to edit the library by yourself.
I have written code for TcpListener in c# which is supposed to receive request from client socket and process the request (send the processed request to our another web service to get final response) then parse the response and send the response back to client socket which initiated the request.
Code snippet below.
Code works fine when receive few requests at a time but now in order to move this to cloud and accept multiple request. We are testing this functionality by running JMeter test on same.
We are getting throughput like 4 when we hit 100 threads per seconds (end to end test - client system to server socket to our web service and back) which should be at least 30 to match client requirement.
If we omit the end to end flow and just send back to hardcode response from server socket itself we are seeing throughput 700.
To find the root cause I have added delay while sending hardcore response (same which we need to communicate with our web service) and I can see same behavior i.e. throughput drastically downgrades = 4/3.8
It means when TcpListener is busy processing existing request it may not attend the next requests (may be I am wrong in assumption - please correct if so)
Please have a look at code and help me increasing the performance .
public void StartTCPServer()
{
Logger.Write_Info_Log("In StartTCPServer - inPort : " + AESDK_CONFIG.PORT_NO, 1, log);
try
{
// Data buffer for incoming data.
byte[] bytes = new Byte[1024];
// Establish the local endpoint for the socket.
IPEndPoint localEndPoint = new IPEndPoint(IPAddress.Any, AESDK_CONFIG.PORT_NO);
// Create a TCP/IP socket.
Socket listener = new Socket(AddressFamily.InterNetwork,
SocketType.Stream, ProtocolType.Tcp);
// Bind the socket to the local endpoint and listen for incoming connections.
listener.Bind(localEndPoint);
listener.Listen(100);
while (true)
{
// Set the event to nonsignaled state.
allDone.Reset();
// Start an asynchronous socket to listen for connections.
listener.BeginAccept(
new AsyncCallback(AcceptCallback),
listener);
// Wait until a connection is made before continuing.
allDone.WaitOne();
}
}
catch (Exception Ex)
{
Logger.Write_Fatal_Log("Exception in Start Listening : " + Ex.Message, 1, log);
}
}
public void AcceptCallback(IAsyncResult ar)
{
// Signal the main thread to continue.
allDone.Set();
// Get the socket that handles the client request.
Socket listener = (Socket)ar.AsyncState;
Socket handler = listener.EndAccept(ar);
// Create the state object.
StateObject state = new StateObject();
state.workSocket = handler;
handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReadCallback), state);
}
public void ReadCallback(IAsyncResult ar)
{
String strdata = String.Empty;
// Retrieve the state object and the handler socket
// from the asynchronous state object.
StateObject state = (StateObject)ar.AsyncState;
Socket handler = state.workSocket;
// Read data from the client socket.
int bytesRead = handler.EndReceive(ar);
if (bytesRead > 0)
{
// There might be more data, so store the data received so far.
state.sb.Append(Encoding.ASCII.GetString(
state.buffer, 0, bytesRead));
// Check for end-of-file tag. If it is not there, read
// more data.
strdata = state.sb.ToString();
if (!string.IsNullOrEmpty(strdata))
{
// All the data has been read from the client.
if (strdata.Contains("<<CheckConnection>>"))
{
log.Info(GlobalVar.gThreadNo(GlobalVar.gintCurrentThread) + "Data Received: " + strdata);
byte[] byData1 = System.Text.Encoding.UTF8.GetBytes("<<CheckConnectionAlive>>");
Send(handler, "<<CheckConnectionAlive>>");
}
else
{
Interlocked.Increment(ref m_clientCount);
//Process incoming requests here and send response back to client
string strResponse = GetRequest(strdata, m_clientCount);
Send(handler, strResponse);
}
}
else
{
// Not all data received. Get more.
handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReadCallback), state);
}
}
}
private static void Send(Socket handler, String data)
{
// Convert the string data to byte data using ASCII encoding.
byte[] byteData = Encoding.ASCII.GetBytes(data);
// Begin sending the data to the remote device.
handler.BeginSend(byteData, 0, byteData.Length, 0,
new AsyncCallback(SendCallback), handler);
}
private static void SendCallback(IAsyncResult ar)
{
try
{
// Retrieve the socket from the state object.
Socket handler = (Socket)ar.AsyncState;
// Complete sending the data to the remote device.
int bytesSent = handler.EndSend(ar);
Console.WriteLine("Sent {0} bytes to client.", bytesSent);
handler.Shutdown(SocketShutdown.Both);
handler.Close();
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}
I am using Netty to setup a simple http/2 server. I am using this example as http/2 server.
To test this server, I am using netty example client.
My client code where I am sending the request to server:
Complete code : http://netty.io/5.0/xref/io/netty/example/http2/client/package-summary.html
HttpResponseHandler responseHandler = initializer.responseHandler();
int streamId = 3;
HttpScheme scheme = SSL ? HttpScheme.HTTPS : HttpScheme.HTTP;
AsciiString hostName = new AsciiString(HOST + ':' + PORT);
System.out.println("Sending request(s)...");
if (URL != null) {
System.out.println("with url");
// Create a simple GET request.
FullHttpRequest request = new DefaultFullHttpRequest(HTTP_1_1, GET, URL);
request.headers().add(HttpHeaderNames.HOST, hostName);
request.headers().add(HttpConversionUtil.ExtensionHeaderNames.SCHEME.text(), scheme.name());
request.headers().add(HttpHeaderNames.ACCEPT_ENCODING, HttpHeaderValues.GZIP);
request.headers().add(HttpHeaderNames.ACCEPT_ENCODING, HttpHeaderValues.DEFLATE);
responseHandler.put(streamId, channel.writeAndFlush(request), channel.newPromise());
streamId += 2;
}
Above code works fine with stream id 3,5 and so on.
But when i change the stream id to any other number like 4,6,8 etc, above code doesn't work. From server I still get the messages for stream id 3,5,7 etc. I am unable to find the logic for these stream id inside example server
Stream numbering is mandated by the HTTP/2 specification.
I'm using socket with O_NONBLOCK, select, keep alive connection and something like HTTP.
each server connection and client side uses a buffer to get all sent data until complete message be received
How to working:
client send data "A"
client try receive response from server
server receive but don't reply immediately
client gets timeout
server send response "A" (but client don't receive now)
another request:
client send data "B"
server send response "B"
client receive "AB" response instead only "B"
the problem is that client receives previous buffer message
source code bellow:
Server.cpp base class:
bool Server::start()
{
struct sockaddr_in client_addr;
SOCKET client_socket, max_sock;
Connection* conn;
int addrlen = sizeof(struct sockaddr_in);
std::list<Connection*>::iterator it, itr;
int response;
fd_set fdset, read_fds;
max_sock = m_socket;
FD_ZERO(&fdset);
FD_SET(m_socket, &fdset);
onStart();
while(true)
{
// make a copy of set
read_fds = fdset;
// wait for read event
response = select(max_sock + 1, &read_fds, NULL, NULL, NULL);
if(response == -1)
break;
// check for new connections
if(FD_ISSET(m_socket, &read_fds))
{
response--;
// accept connections
client_socket = accept(m_socket, (struct sockaddr*)&client_addr, &addrlen);
if(client_socket != INVALID_SOCKET)
{
conn = new Connection(*this, client_socket, &client_addr);
m_connections.push_front(conn);
// add connection to set for wait for read event
FD_SET(client_socket, &fdset);
// allow select new sock from select funcion
if(max_sock < client_socket)
max_sock = client_socket;
}
}
// check for received data from clients
it = m_connections.begin();
while(it != m_connections.end() && response > 0)
{
conn = *it;
// verify if connection can be readed
if(FD_ISSET(conn->getSocket(), &read_fds))
{
response--;
conn->receive();
if(!conn->isConnected())
{
FD_CLR(conn->getSocket(), &fdset);
// remove connection from list
itr = it;
it++;
m_connections.erase(itr);
delete conn;
continue;
}
}
it++;
}
}
onFinish(response >= 0);
return response >= 0;
}
main.cpp Server implementation:
void ClientConnection::onReceive(const void * data, size_t size)
{
const char *str, *pos = NULL;
HttpParser* p;
buffer->write(data, size);
do
{
str = (const char*)buffer->data();
if(contentOffset == 0)
{
pos = strnstr(str, buffer->size(), "\r\n\r\n");
if(pos != NULL)
{
contentOffset = pos - str + 4;
p = new HttpParser((const char*)buffer->data(), contentOffset);
contentLength = p->getContentLength();
delete p;
}
}
if(buffer->size() - contentOffset < contentLength || contentOffset == 0)
return;
proccessRequest();
keepDataStartingOf(contentOffset + contentLength);
}
while(buffer->size() > 0);
}
client side code is a simple recv send with timeout
any idea how to solve?
The first thing that comes to mind is to make the client's timeout large enough that the client won't timeout unless the server is actually dead... but I'm sure you've already thought of that. :)
So assuming that's not a good enough fix, the next thing to try is to have the client send an ID number with each request it sends. The ID number can be generated with a simple counter (e.g. for the client's first request, it tags the request with 0, for the second it tags it with 1, etc). The server, when sending its reply, will include that same ID number with the reply.
When the client receives a reply, it compares the ID number in the reply data against the current value of its counter. If the two numbers are the same, it processes the data. If not, it ignores the data. Et voila!