I Receive Many UDP Connection From None IP Valid Devices With This Code:
receivingUdpClient = New System.Net.Sockets.UdpClient(Port)
Dim byteBuffer As [Byte]() = receivingUdpClient.Receive(RemoteIpEndPoint)
Now I Want Response Data To Device After Receive Data
I use This Code
receivingUdpClient.Send(receiveBytes, 10)
Buy Recived This Error :
"The operation is not allowed on non-connected sockets."
In general, you you need to use SendTo and ReceiveFrom methods instead of Send and Receive with UDP sockets. That way, you can get the IP:port (endpoint) of the sender - so you can send the response back to that same address. My VB is weak, so I'll give you a simple example in C#.
byte [] buffer = new byte[1500];
IPEndPoint sender = new IPEndPoint(IPAddress.Any, 0);
EndPoint senderRemote = (EndPoint)sender;
EndPoint senderRemote;
int bytesReceived = socket.recvFrom(buffer, senderRemote);
// echo the message back to the sender
if (bytesReceived > 0)
socket.sendTo(buffer, bytesReceived, senderRemote);
In your code, RemoteIpEndPoint captures the address you received the data from. To send data back to that host you need to pass that address (endpoint) to your call to Send.
Related
I want implement some functional like user send me a message and I reply to him with my (bot) latest message from chat history.
As you can see in the Telegram Bot API Documentation you can use sendMessage to send a message to the user.
When you receive a message, look for the chat or the from parameter in the JSON (depends if you want to answer to the person when it's a group chat or not). You can use the id parameter of the chat or from to send the message.
So the first parameter for your sendMessage would be chat_id=message.chat.id
You don't need the parse_mode, disable_web_page_preview and reply_markup for this example.
As you want to reply to the message of the user you may want to set the reply_to_message_id to the id of the received message.
reply_to_message_id = message.message_id
Last but not least, you want to set the text parameter. If I understand it correctly, your program will send the last received message.text to the user.
So what you want to do is, as soon as you get a message, save it.
Message oldMessage = message
And when you send the Message to the user use the old messages text property as the text.
text = oldMessage.text
Alright to sum it up here is the pseudocode of the function that will happen as soon as you receive a message:
Message oldMessage = null;
public void NewMessage(Message message){
int chat_id = message.chat.id;
int reply_to_message_id = message.message_id;
String text = "There is no old Message"; //fallback value
if(oldMessage != null){
text = oldMessage.text;
}
//Send Message in this example only has 3 parameters, and ignores the
//not used ones
SendMessage(chat_id,text,reply_to_message_id);
oldMessage = message; //store the received message for future answering
}
As you store the whole message in oldMessage you could also set the text you will send to something like this:
String text = oldMessage.from.first_name+": "+oldMessage.text;
if you simply want to reply on users message you need this function:
public void sendMsg(Message message, String text){
SendMessage sendMessage = new SendMessage();
sendMessage.enableMarkdown(true);
sendMessage.setChatId(message.getChatId().toString());
sendMessage.setReplyToMessageId(message.getMessageId());
sendMessage.setText(text);
try{
setButtons(sendMessage);
sendMessage(sendMessage);
}catch (TelegramApiException e){
e.printStackTrace();
}
}
Is it possible to publish a message to only one client subscribed to channel? I know how to get the address (client list). Is it possible to get the address and publish to only that client?
In Redis you publish to a channel, not to a subscriber.
So the only way should be having one channel per client.
You can probably have one common channel to share the address, and then use the addresses as the channels name.
http://redis.io/topics/pubsub
As an example, using C# and StackExchange.Redis library:
//SERVER
var cnn = ConnectionMultiplexer.Connect("localhost");
var sub = cnn.GetSubscriber();
sub.Subscribe("common", (channel, value) =>
{
Console.WriteLine("SERVER Received in common: {0}", value);
sub.Publish("channel:" + value, "private from server to " + value);
});
//CLIENT
var cnn = ConnectionMultiplexer.Connect("localhost");
var address = "client1";
var sub = cnn.GetSubscriber();
sub.Subscribe("channel:" + address, (channel, value) =>
{
Console.WriteLine("Private: {0}", value);
});
sub.Publish("common", address);
Another solution: what I was trying to do was to have all subscribers listen but only one handle the message. The way I did this was create a stack in redis and have all subscribe to a key's list command notifications. So I would RPUSH a new value onto the key, the subscribers would get the keyspace notification and the fist to LPOP the value would handle it.
I am trying to add an event from my local database to the Davical server (in fact, this should apply to any CalDav server, as long as it is compliant with the CalDav protocol)...
From what I could read here, I can send a PUT request to add events contained in a VCALENDAR collection... So here is what I try to do:
try {
// Create the HttpWebRequest object
HttpWebRequest Request = (HttpWebRequest)HttpWebRequest.Create("http://my_caldav_srv/davical.php/user/mycalendar");
// Add the network credentials to the request
Request.Credentials = new NetworkCredential(usr, pwd);
// Specify the method
Request.Method = "PUT";
// some headers - I MAY BE MISSING THINGS HERE???
Request.Headers.Add("Overwrite", "T");
// set the body of the request...
Request.ContentLength = bodyStr.Length;
Stream reqStream = Request.GetRequestStream();
// Write the string to the destination as a text file.
reqStream.Write( Encoding.UTF8.GetBytes(body), 0, body.Length);
// Set the content type header.
Request.ContentType = contentType.Trim();
// Send the method request and get the response from the server.
Response = (HttpWebResponse)Request.GetResponse();
}
catch (Exception e) {
throw new Exception("Caught error: " + e.Message, e);
}
The body I send is actually an emtpy calendar:
BEGIN:VCALENDAR
VERSION:2.0
CALSCALE:GREGORIAN
METHOD:PUBLISH
PRODID:-//davical.org//NONSGML AWL Calendar//EN
X-WR-CALNAME:My Calendar
END:VCALENDAR
For a reason I cannot understand, the call with "PUT" returns an error (405) Method Not Allowed. The PUSH returns (500) Internal Server Error, but looking at the debug details, the reason is the same as for the PUT case...
In debugging on the server side, I found out that the reason is that in caldav-PUT-vcalendar.php, the following clause is violated:
$c->readonly_webdav_collections
Well, first, let me mention that with the SAME credentials entered in Lightning, I am able to add/remove events and, on the admin interface, I actually made sure to grant ALL rights to the user. So I'd be surprised it is due to that...
Any help would be most appreciated !
Kind regards,
Nik
OK, I got it....
The reason is that one must put the event to some EVENT adress....
I.e. the "url" is not the collection's address, but the EVENT's address...
So the same code using the following address works:
string url="http://my_server/caldav.php/username/calendarpath/_my_event_id.ics";
Does anybody know if it is possible to insert / delete multiple events at once ???
I'm new to RabbitMQ and was wondering of a good approach to this problem I'm mulling over. I want to create a service that subscribes to a queue and only pulls messages that meet a specific criteria; for instance, if a specific subject header is in the message.
I'm still learning about RabbitMQ, and was looking for tips on how to approach this. My questions include: how can the consumer pull only specific messages from the queue? How can the producer set a subject header in the message (if that's even the right term?)
RabbitMQ is perfect for this situation. You have a number of options to do what you want. I suggest reading the documentation to get a better understanding. I would suggest that you use a topic or direct exchange. Topic is more flexible. It goes like this.
Producer code connects to the RabbitMQ Broker and creates and Exchange with a specific name.
Producer publishes to exchange. Each message published will be published with a routing key.
Consumer connects to RabbitMQ broker.
Consumer creates Queue
Consumer binds Queue to the exchange, the same exchange defined in the producer. The binding also includes the routing keys for each message require for this particular consumer.
Lets say you were publishing log messages. The routing key might be something like "log.info", "log.warn", "log.error". Each message published by the producer will have the relevant routing key attached. You will then have a consumer that sends and email for all the error messages and another one that writes all the error messages to a file. So the emailer will define the binding from its queue to the exchange with the routing key "log.error". This way though the exchange receives all messages, the queue defined for the emailer will only contain the error messages. The filelogger will define a new separate queue bound to the same exchange and set up a different routing key. You could do three separate bindings for the three different routing keys require or just use the wildcard "log.*" to request all messages from the exchange starting with log.
This is a simple example that shows how you can achieve what you want to do.
look here for code examples specifically number tutorial number 5.
Making the best of exchange/routing of rabbitmq is recommended. If you do want to check according to the message content, the following code is a viable solution.
Retrieve messages from a queue and check, selectively ack the messages in which you're interested.
pull one message
GetResponse resp = channel.basicGet(QUEUE_NAME, false);
ack one message
channel.basicAck(resp.getEnvelope().getDeliveryTag(), false);
Example
import com.rabbitmq.client.*;
public class ReceiveLogs {
private final static String QUEUE_NAME = "hello";
public static void main(String[] argv) throws Exception {
ConnectionFactory factory = new ConnectionFactory();
factory.setHost("localhost");
try(Connection connection = factory.newConnection();
Channel channel = connection.createChannel();){
channel.queueDeclare(QUEUE_NAME, true, false, false, null);
// pull one message and ack manually and exit
GetResponse resp = channel.basicGet(QUEUE_NAME, false);
if( resp != null ){
String message = new String(resp.getBody(), "UTF-8");
System.out.println(" [x] Received '" + message + "'");
channel.basicAck(resp.getEnvelope().getDeliveryTag(), false);
}
System.out.println();
}
}
}
dependency
compile group: 'com.rabbitmq', name: 'amqp-client', version: '5.8.0'
To Retrieve Message from RabbitMQ we need to first connect with RabbitMQ server
public WebClient GetRabbitMqConnection(string userName, string password)
{
var client = new WebClient();
client.Credentials = new NetworkCredential(userName, password);
return client;
}
Now retrieve message from RabbitMQ using below code.
public string GetRabbitMQMessages(string domainName, string port,
string queueName, string virtualHost, WebClient client, string methodType)
{
string messageResult = string.Empty;
string strUri = "http://" + domainName + ":" + port +
"/api/queues/" + virtualHost + "/";
var data = client.DownloadString(strUri + queueName + "/");
var queueInfo = JsonConvert.DeserializeObject<QueueInfo>(data);
if (queueInfo == null || queueInfo.messages == 0)
return string.Empty;
if (methodType == "POST")
{
string postbody = "
{\"ackmode\":\"ack_requeue_true\",\"count\":
\"$totalMessageCount\",\"name\":\"${DomainName}\",
\"requeue\":\"false\",\"encoding\":\"auto\",\"vhost\" :
\"${QueueName}\"}";
postbody = postbody
.Replace("$totalMessageCount", queueInfo.messages.ToString())
.Replace("${DomainName}", domainName)
.Replace("${QueueName}", queueName);
messageResult = client.UploadString(strUri + queueName +
"/get", "POST", postbody);
}
return messageResult;
}
I think this will help you to implement RabbitMQ.
If you want to retrieve single message at a time please add the following properties with your Retrieving code .
Boolean autoAck = false;
model.BasicConsume(Queuename, autoAck);
model.BasicGet("Queuename", false);
model.BasicGet("Queuename", false);
By adding this properties of RabbitMQ you can retrieve the message one by one from the queue .Same like FIFO criteria
My code looks very similar to this post Read bytes from NetworkStream (Hangs), which I copied below. ( I realize this is c# - I need a vb solution)
// Create a TcpClient.
// Note, for this client to work you need to have a TcpServer
// connected to the same address as specified by the server, port
// combination.
TcpClient client = new TcpClient(server, port);
// Translate the passed message into ASCII and store it as a Byte array.
Byte[] data = System.Text.Encoding.ASCII.GetBytes(message);
// Get a client stream for reading and writing.
NetworkStream stream = client.GetStream();
// Send the message to the connected TcpServer.
stream.Write(data, 0, data.Length);
Console.WriteLine("Sent: {0}", message);
// Receive the TcpServer.response.
// Buffer to store the response bytes.
data = new Byte[256];
// String to store the response ASCII representation.
String responseData = String.Empty;
// Read the first batch of the TcpServer response bytes.
Int32 bytes = stream.Read(data, 0, data.Length);
responseData = System.Text.Encoding.ASCII.GetString(data, 0, bytes);
Console.WriteLine("Received: {0}", responseData);
// Close everything.
stream.Close(); client.Close();
My issue lies in this:
I have a form that takes user input on which tif file(s) to find (which ends up being the getBytes(message) ). When one does this, it always returns one result - the first tif file that fits the criteria, However, I know in certain instances I should recieve more than one match.
Then I send the results to a picturebox and should be able to scroll through results (which this part works fine)
I've tried a few ways to get multiple results, but maybe I'm missing the obvious? My best guess is using the asyncronous beginread/write....
I've attempted using a for loop but I end up getting a bunch of the same tif files as a result...
Could anyone help me (even with a generic direction)? I'm not a pro. Thanks in advance for the help.
I ended up finding out what the issue was. the data i was looking for wasn't standardized as so the results were the same data over and over. I changed what items I was looking for and tada it worked. anyway, thanks for the help