I am creating a websocket chat application and I managed to relay chat messages to other browsers connected. I have a console application listening on one port.
My question is... If one person logs on to the system I want everybody to know that, how can I do that? I'm using Linq to map the DB but if the logging is ok how do I send that message, that user X has logged in?
FINALLY I was able to create a chatroom using websockets, here is the final product, thanks for the orientation!
http://ukchatpoint.no-ip.org/Chatpoint/Pages/Uklobby.aspx
First make sure you're sending messages as JSON (JavaScript Object Notation) as this allows structured data to be sent back and forth, and client & server can differentiate between a chat message and an instruction (e.g. someone new logged in). For instance on the client:
mySocket.onmessage = function(event) {
var command = JSON.parse(event.data);
if(command.type === 'message') {
var message = command.message;
// handle chat message
}
else if (command.type === 'newUser') {
var username = command.username;
// handle new user
}
};
On the server in ASP.NET C# you'd send them as:
public class ChatHandler : WebSocketHandler
{
private JavaScriptSerializer serializer = new JavaScriptSerializer();
private static WebSocketCollection chatapp = new WebSocketCollection();
public override void OnMessage(string message)
{
var m = serializer.Deserialize<Message>(message);
switch (m.Type)
{
case MessageType.NewUser:
chatapp.Broadcast(serializer.Serialize(new
{
type = "newUser",
username = m.username
}));
break;
case MessageType.Message:
chatapp.Broadcast(serializer.Serialize(new
{
type = "message",
message = m.message
}));
break;
default:
return;
}
}
}
As Hightechrider says, you'll need to keep track of a list of connected clients, that's what WebSocketCollection class does in the code listing above.
Check out Paul Batum's WebSocket chat example on github here (https://github.com/paulbatum/BUILD-2011-WebSocket-Chat-Samples/blob/master/BasicAspNetChat/ChatHandler.cs)
Also he did a presentation at the recent MS BUILD conference here (http://channel9.msdn.com/Events/BUILD/BUILD2011/SAC-807T)
You would need to track the connections at the application level so you can send to all of them. But take a look at SignalR instead where a lot of the work involved with webSockets and long polling is being written for you. With SignalR you can use GetClients to get all the clients connected to a Hub.
When using PostgreSQL, you could use NOTIFY from within the database to notify the application layer, which could generate messages sent via WebSockets.
Related
I have a server that needs to get instructions to run processes for clients on another machine.
The clients send a job message, the Server processes the job and later sends the back results.
I tried using the NetMQ Request-Response pattern (see below)
This works nicely for 1 client, BUT if a second client sends a request before previous client job is finished - I get an error.
I really need to be able to receive ad-hoc messages from clients, and send results when they are completed. Clearly, I am using the wrong pattern, but reading the ZeroMQ docs has not highlighted a more appropriate one.
namespace Utils.ServerMQ
{
class ServerMQ
{
public static void Go()
{
using (var responseSocket = new ResponseSocket("#tcp://*:393"))
{
while (true)
{
Console.WriteLine("Server waiting");
var message = responseSocket.ReceiveFrameString();
Console.WriteLine("Server Received '{0}'", message);
//System.Threading.Thread.Sleep(1000);
var t2 = Task.Factory.StartNew(() =>
{
RunProcMatrix(message, responseSocket);
});
}
}
}
public static void RunProcMatrix(object state, ResponseSocket responseSocket)
{
var process = new Process
{
StartInfo = new ProcessStartInfo
{
FileName = Path.Combine(#"H:\Projects\Matrix\Matrix\bin\Debug\", "Matrix001.exe"),
Arguments = (string)state,
WindowStyle = ProcessWindowStyle.Normal,
CreateNoWindow = false
}
};
process.Start();
process.WaitForExit();
responseSocket.SendFrame((string)state);
}
}
}
You want a ROUTER socket on the server side, so it can receive multiple requests at a time. (Guide) REQ sockets on the client side are still fine unless the server may arbitrarily push data to them, then they need to be DEALER sockets.
Note that for sockets beyond REQ/RESP you need to manually handle the message envelope (the first frame of the message indicating its destination). Guide
The 0MQ docs are incredibly dense... I don't blame you for not intuiting this from them :)
This example from the NetMQ docs is full ROUTER-DEALER: https://netmq.readthedocs.io/en/latest/router-dealer/#router-dealer, you can take just the router side and it should work the same though.
I wish to send messages to a client directly via their IP address. I am currently only able to send messages when ChannelRead0 is called in the handler and grabbing the context from there:
protected override void ChannelRead0(IChannelHandlerContext ctx, DatagramPacket packet) {
ctx.WriteAsync(new DatagramPacket(buffer, packet.Sender));
}
My bootstrapper:
var bootstrap = new Bootstrap();
bootstrap
.Group(group)
.Channel<SocketDatagramChannel>()
.Option(ChannelOption.SoBroadcast, true)
.Handler(new LoggingHandler("SRV-LSTN"))
.Handler(new ActionChannelInitializer<IChannel>(channel => {
channel.Pipeline.AddLast("UDPServer", new protocols.UDP());
}));
IChannel boundChannel = await bootstrap.BindAsync(8888);
I want to be able to send messages from outside this function as well. Is there any way in which I can send a client a message from outside this function / class? I have tried writing to boundChannel however it appears that it doesn't wave a .write or .writeAsync function.
I am using the DotNetty library (https://github.com/Azure/DotNetty) which was ported from Java.
An IChannel has an WriteAndFlushAsync method that you can use to write a message, this is similair to the writeAndFlush method in the Java version of Netty.
I'm trying to host a websockets server on Azure. I'm a bit confused and was hoping you could help me.
I've followed many articles but my code is close to the one from this article : https://azure.microsoft.com/en-us/blog/introduction-to-websockets-on-windows-azure-web-sites/
public void ProcessRequest(HttpContext context)
{
if (context.IsWebSocketRequest)
{
context.AcceptWebSocketRequest(ProcessWS);
}
}
public bool IsReusable { get { return false; } }
private async Task ProcessWS(AspNetWebSocketContext context)
{
try
{
WebSocket socket = context.WebSocket;
while (true)
{
var url = context.RequestUri;
ArraySegment<byte> buffer = new ArraySegment<byte>(new byte[1024]);
WebSocketReceiveResult result = await socket.ReceiveAsync(buffer, CancellationToken.None);
if (socket.State == WebSocketState.Open)
{
string userMessage = Encoding.UTF8.GetString(buffer.Array, 0, result.Count)
.Trim(new char[] { ' ' }); // We remove the spaces before and after
// DO SOMETHING
}
else
{
break;
}
}
}
catch (Exception e)
{
Log.Info("Exception" + e.Message + " >>>" + e.StackTrace);
}
}
This works fine, I'm able to get the messages from my devices and answer to them.
But in some cases I need to send a message to another device, example :
DEVICE A sends "Tell Device B to blink"
Since it's a websockets server and Device B has already talked with the server I should have somewhere a connection opened with Device B. And when Device A asks me for it I can send a message to Device B.
But how can I achieve that with my code ? How can I find the connection to device B ? If not possible how should I do it ?
I hope my problem is described enough to be understood.
Thank you,
But how can I achieve that with my code ? How can I find the connection to device B ? If not possible how should I do it ?
According to your scenario, I followed this tutorial about webapi-and-websockets and implement my Web API project that could establish connection between clients. Here is the screenshoot for test, you could refer to it:
Additionally, you could leverage SignalR and map your client (user) to signalR connections. For more details, you could refer to Mapping SignalR Users to Connections. Also, you could refer to the git sample Microsoft.AspNet.SignalR.Samples.
UPDATE:
How would you use signalR in that case ?
For a simple way, we could retain connection and user info stored in memory, For more details, you could refer to In-memory storage. Based on this scenario, I wrote a sample project AspDotNet-SignalR-Chat, you could refer to it, and here is the screenshot for test:
hello all i have this issue , and i am stuck with it so any help will be greatly appreciated
i have to build a socket chat (client Server) module and i have done almost 80% of the work but now i am stuck , Scenario is that i have a server app and clients connect to it now if say 4 clients are connected to server each of them can communicate to each other , one client will send message and server will receive that message and will pass it along ,this is working very fine but when 2 or more clients send a message to 3rd client at the same time than i can not get one message and client get disconnected i know i have to build up a queue structure but i am not getting succeeded in it here
here is my code structure
StartReceive(SocketAsyncEventArgs) ->
First of all i call this method to start listening for incoming messages
and when i got one message i check if it is completed Sync or Async
and after this there is an io completed listener which is called every time one receive opertaion is completed and in that io completed method i do call processReceive method which is used to process received chunks
so finally my code structure is like this
StartReceive-> IO Completed -> ProcessReceive
i have designed the structure so that every client will have a Receive SOCKETASYNCEVENTAGRS
object and a Send SOCKETASYNCEVENTAGRS at server side and i do maintain a pool for this
so each client receives and sends data through its own SOCKETASYNCEVENTAGRS object
i want a scenario such that if two or more clients send messages to 3rd client than 3rd client should not receive all messages at the same time instead it should have a queue structure and it should receive one message at a time and same for send operation
here is some of my code
private void StartReceive(SocketAsyncEventArgs receiveSendEventArgs)
{
DataHoldingUserToken receiveSendToken = (DataHoldingUserToken)receiveSendEventArgs.UserToken;
receiveSendEventArgs.SetBuffer(receiveSendToken.bufferOffsetReceive, this.socketListenerSettings.BufferSize);
bool willRaiseEvent = receiveSendEventArgs.AcceptSocket.ReceiveAsync(receiveSendEventArgs);
if (!willRaiseEvent)
{
ProcessReceive(receiveSendEventArgs);
}
}
This is IO Completed
void IO_Completed(object sender, SocketAsyncEventArgs e)
{
DataHoldingUserToken receiveSendToken = (DataHoldingUserToken)e.UserToken;
switch (e.LastOperation)
{
case SocketAsyncOperation.Receive:
ProcessReceive(e);
break;
default:
}
}
and this is my StartReceive with Queue implemented but it is not working
Queue rec = new Queue();
bool IsExecuted = true;
private void StartReceive(SocketAsyncEventArgs receiveSendEventArgs)
{
if (IsExecuted)
{
DataHoldingUserToken receiveSendToken = (DataHoldingUserToken)receiveSendEventArgs.UserToken;
rec.Enqueue(receiveSendToken);
}
try
{
receiveSendEventArgs.SetBuffer(receiveSendToken.bufferOffsetReceive, this.socketListenerSettings.BufferSize);
bool willRaiseEvent = receiveSendEventArgs.AcceptSocket.ReceiveAsync(receiveSendEventArgs);
if (!willRaiseEvent)
{
ProcessReceive(receiveSendEventArgs);
}
rec.Dequeue();
IsExecuted = true;
}
catch
{
IsExecuted = false;
StartReceive(receiveSendEventArgs);
}
}
looking for a decent help or some good direction
I'm not sure if this is the root cause of your problem but it seems to me that you are running out of DataHoldingUserToken at some time because you are never doing anything with the objects you dequeue, hence you are throwing it away.
Also note that it is recommended to use the generic form of the Queue class for non-trivial object. That would be System.Collections.Generic.Queue<DataHoldingUserToken>.
At this line of code i am getting the error as i mentioned
I declared MSMQ_NAME as string as follows
private const string MSMQ_NAME = ".\\private$\\ASPNETService";
private void DoSomeMSMQStuff()
{
using (MessageQueue queue = new MessageQueue(MSMQ_NAME))
{
queue.Send(DateTime.Now); //Exception raises
queue.Close();
}
}
Can you first verify the queue is existing with the name 'ASPNETService' at below location?
Computer Management -> Services and Applications -> Message Queuing -> Private Queues
I had a similar problem. I was confused because my code worked on my local development machine, but not in production. Even stranger, the queues were created the exact same way.
It turns out that IIS doesn't have access to them by default. I just opened up the permissions.
Computer Management -> Private Queues -> right-click queue name -> Properties -> Security Tab -> click "Everyone" user -> click Full Control/Allow checkbox -> click OK
This fixed it for me, and in my case it's not an issue, but you may want to think about the ramifications of just opening it up for all users.
Also, I had to do this across all queues on all servers. There doesn't seem to be a way to multi-select queues or folders in order to set permissions for multiple queues simultaneously.
I was having the same problem.
I had created a new private queue and gave Full Permission to Everyone.
But I was still catching a "Queue does not exist or you do not have sufficient permissions to perform the operation" when trying to Send() to the queue. And I was able to verify that MessageQueue.Exists(".\\private$\\myqueue") was returning true.
Restarting the Message Queuing Service resolved my the problem for me.
I had same problem and I did like below where I check whether queue exists or not. If yes send message else create queue and then send message
MessageQueue msgQueue = null;
string queuePath = ".\\Private$\\billpay";
Payment newPayment = new Payment()
{
Payee = txtPayee.Text,
Payor = txtPayor.Text,
Amount = Convert.ToInt32(txtAmount.Text),
DueDate = dpDueDate.SelectedDate.Value.ToShortDateString()
};
Message msg = new Message();
msg.Body = newPayment;
msg.Label = "Gopala - Learning Message Queue";
if (MessageQueue.Exists(queuePath) == false)
{
//Queue doesnot exist so create it
msgQueue = MessageQueue.Create(queuePath);
}
else
{
msgQueue = new MessageQueue(queuePath);
}
msgQueue.Send(msg);
I was facing the same problem, I had resolved it using the following class to create queue
private MessageQueue messageQueue;
public const string DEFAULT_QUEUE_NAME = "newQueue";
public const string QUEUENAME_PREFIX = ".\\Private$\\";
public static string QueueName
{
get
{
string result = string.Format("{0}{1}", QUEUENAME_PREFIX, DEFAULT_QUEUE_NAME);
return result;
}
}
public void SendMessage()
{
string queuePath = QueueName;
MessageQueue messageQueue = MessageQueue.Create(queuePath);
messageQueue.Send("msg");
}
Create message queue in same manner for receiving the message.
For others struggling with this and pulling their hair out like I have been, I finally found something that works when all of the upvoted suggestions failed.
Even if you think the host name of your target queue's hosting system is being resolved correctly, don't believe it. Try replacing the host name with an IP address and see if it works. It does for me. I can WRITE to a public queue using a host name on my remote server without problems, but trying to READ from it produces exactly the error listed for this question.
For example, if I declare the following:
private static string QueueName = #"FormatName:DIRECT=TCP:SOMEHOST\MyQueue";
private static System.Messaging.MessageQueue Queue = new System.Messaging.MessageQueue(QueueName);
Where "MyQueue" is a public queue on server SOMEHOST, the following code will successfully insert messages to the queue, but always fails on the Receive():
Queue.Formatter = new XmlMessageFormatter(new Type[] { typeof(String) });
// The Receive() call here is a blocking call. We'll wait if there is no message in the queue, and processing
// is halted until there IS a message in the queue.
//
try
{
Queue.Send("hello world", System.Messaging.MessageQueueTransactionType.Single);
var msg = Queue.Receive(MessageQueueTransactionType.Single);
}
catch (Exception ex)
{
// todo error handling
}
One simple change in how I specify the queue location is all that's needed to make the Receive() stop failing with the dreaded "queue does not exist or you do not have sufficient permissions" error:
private static string QueueName = #"FormatName:DIRECT=TCP:192.168.1.100\MyQueue";
(Obviously I've obfuscated IP addresses and other sensitive info). Using the IP address is not obviously a production-worthy scenario, but it did point me to some type of name resolution problem as being the possible cause of the error. I cannot explain why Send() works but Receive() does not when I am using a host name instead of IP, but I can reproduce these results consistently. Until I can figure out what's going on with the name resolution, I'm no longer wasting a day trying to read messages from a queue.