I'm building a UDP server that handles each incoming request in a separate
thread. The problem is, a UDP client may send out multiple requests
concurrently by using multiple threads. Each thread on the client will wait
for responses from the server. Since UDP is connectionless, a client thread
may receive a mismatching datagram. In this case, does have any
built-in mechanism or pattern that helps a client thread to get the matching response?
(for example send each request from server to specific udp port !!?)
I don't want use queue because it lost concurrently property.
If not, I guess we can build a queue that dispatches responses to
appropriate client threads. However, what if I need to run multiple clients
in different JVMs on the same client machine, and each client will make
requests to the same server?
Use a separate socket for each udp client. That way you have a different ip and port for sending and would receive response on the same i.e. the client which sent the request would only receive it's response (i presume that is what you meant by matching) This should be done automatically unless you share the same socket between threads and use it to send messages to server which seems like a bad idea.
You can set any port in your source (sender port) in client before sending message to server. The server can extract your source port and respond to the same port
e.g.
Client 1 source port:10401 -> server:listening port:2000. Server responds to port 10401.
Client 2 source port:10402 -> server: listening port: 2000. Server responds to port 10402.
If you are wanting to do concurrent connections, make multiple connections. Spawn a new UDP connection on the client, the server will just open a new connection on it's end. Anything sent on connection1 on the client comes in on comes on on connection1 on the server, anything sent on connection2 gets received on connection 2.
Related
I am using Tcplistener to listen on a port for requests. When the requests come in from the client I want to know the client ip making the request.
the problem is : the server and all client take the same Ip
so I decided to send massage from server to client by port ... I search a lot on google But I did not knew how I can send message from server to client using the port ? so can any body help me ?
The clients are not listening for incoming connections, so the only way for the server to send a message to a client is by using an existing connection, that was previously established by the client.
You don't have to specify the port number when sending a message on an existing connection, your server can just use:
Socket handlerSocket = tcpListener.AcceptSocket();
// a connection is now established, "handlerSocket" can be used for both receiving and sending messages
handlerSocket.Send(...);
Your clients currently send data and immediately close the connection though, you'll have to modify them to read data from the NetworkStream in order to receive anything.
There are tons of tutorials available, I think you just googled the wrong keywords. Have you tried something like c# chat tutorial?
You are running them all in the same computer. That is why the IP is always the same.
SOP for this kind of thing is to have two ports: a control port and a data port.
The way this works is:
The control port is used to initiate the connection.
Upon successful connection, the server and the client negotiate a set of ports to be used for the data (local server data port and remote client data port).
The server establishes a connection to the remote client data port from the local server data port.
The client issues a request for data (e.g. command) through the control port.
The server sends the information back through the data port.
is it possible to have one socket router that would pass incoming sockets to socket servers?
I need this because I want to have multiple servers for handling sockets but only one port for clients to connect to. so if one of the servers goes down, router would send the socket to other healthy socket servers.
Is this even possible and how? or any other solution for my problem?
Yes this is definitely possible, and is used very widespread.
Basically you need to have one TCP server running on that one port you want clients to connect to. Then you can listen for connections. When a connection is established you can reroute packets to other servers (you choose).
Listen on a port with your main server
Accept connections as they come in.
When a connection is opened, read the data in another thread. Take that data and send it to the other server you want to.
Basically, it is a proxy.
I've no idea how I would go about this but I'm assuming that it is possible in some way, shape or form.
If I have a server that allow multiple connections to it through one port, is there a way I can make some sort of log of the connections, so that I could choose a certain connection to send a message to? Also if this is possible.
Is it also possible to do the same with connections through different ports?
How would I go about this? I'm fairly new to C# so not very experienced - any help is greatly appreciated!
Basically I want 3 clients to connect to a server. The clients will all send a message to the server, and the server will wait for a message from each client before replying to them, in the order in which the messages were sent.
I hope this makes more sense now.
If you are using TCP/IP, this is very much possible - the Socket that listens for incoming connections only does that - it does not handle the communication with each individual socket. Instead, the Accept() and BeginAccept() methods return a new Socket instance for each client that connects.
So the Socket instance you get when a client connects only receives messages from that client, and sending a message on that socket sends it to only that client.
Keeping track of which connection sent what - and which came first - will be more of a challenge, but definately possible.
If you are using UDP though things are a bit different, you would need to use a custom means of identifying each client.
i am wondering how tcp servers work because there is no multicasting. I am interested in using tcp for my game since it won't require to much packets to be sent like some other games. It still needs to have a client / server architecture though.
Since there is no multicasting, is there just a loop to send everything directly from server to client for every client? Is this what minecraft does (cuz i read it uses tcp)
it was my understanding that only 1 socket can be bound to a port. With udp, the server socket can accept connections from IPAdress.Any, so it can receive information from all clients. Since TCP is connection only, how would this work? Can multiple TCP connections be made on the same socket?
Only one listening connection can exist per port on the server. However, many clients can connect to that one listening port. A "Connection" under the hood is the combination of ServerIP + ServerPort + ClientIP + ClientPort, also the client port does not need to be the same every time (only the server side port needs to stay static), the OS chooses a random high number port and give that to the client side for the connection. That is why you can have many outgoing connections on a client but only one listening connection on the server.
Look at this page for a example on how to set up multiple connections to one port.
I have a custom TCP Server listening on port 5888(dummy port). The proxy server listens for incoming connections. When the proxy receives HTTP request for certain pages, it should relay it to the main server on port 80.For other page requests the proxy is required to send data to the main Server on port 8081.
The port 80 is used to service the HTML Pages where as the port 8081 is used for streaming data to the clients.
I am able to receive the incoming connections on the proxy and then read the data from the clients. After reading the data, I can determine which port to connect to on the main server for sending the data.
I am stuck at deciding how to connect on 2 ports for sending the data from the clients to the Main Server?
In that case you either need 2 socket connection objects to the same IP on the different ports (this is legal), or you have one connection object which reconnects according to the port you have to deal with.
Depending on how often you have to switch connections the latter version might have a huge overhead, plus the first one allows you to send data to both ports virtually simultaneously.
You need to stop thinking of your program as a server. After you have received the connection, read the data, and decided what port to send it to, shift gears and start operating as a client would.
Just open a new connection to "localhost" on either port 80 or 8081 and re-send the data you received as if you were the original client.
Your client is connected to the proxy server on port 5888 so no matter from what real server (Web or streaming) you take the data, you are going to provide the data to the client using port 5888 only.
It seems to be a not so practical solution. I am assuming here that you are trying to achieve a kind of control port and data port structure where one port is controlling the streaming from another port.
Just creating two sockets is sufficient for obtaining data from two servers. Here you will have to manually create a protocol which your client understands as you are going to provide both html and streaming data to the client using single port.