ClientA and Client B connect to the NettyServer.
when the connection builds, there is a channel between Client and NettyServer, I want when channel active, I can add Client side info in the channel, so that I can store like Map(ClientInfo,Channel). The on the server side, I can use Map.get(ClientInfo) to get the specific channel, then I can use channel.writeAndFlush() to send message to the specific client.
how to implement it? Use attachment? But, in neety5 API ChannelHandler, the attachment example is not the way I want to use. I wander if I can add attachment at Client side, and I can get it at the Server side?
You can use the AttributeKey or AttributeMap to store your client info, and store them into channel or channelContext, if necessary you can use them using get or set method.
Related
I did a simple chatserver in the java ... I'm wondering about adding a username to a chat that you need to enter when you enter chat. Also, I do not understand how private messages are sent only to the addressee
If the destination is not logged in to the chat server, the error message should be sent to the sender
Each message sent by the server to the client must be accompanied by the name of the original sender and the time when the message was sent.
Java Code ---> https://dijaspora24.info/?page_id=4123
I am not going to show the implementation, since it's a big problem to solve here. However, I will give an idea of how to implement this.
I assume you know how to connect a client to a server (for example by using ServerSocket and Socket).
First, to add the username of a connected client, the server simply has to force the client enter a string to the server as the first thing when it connects to the server.
Second, create a Map to store all clients, where key is the username entered and value is the socket.
Third, when a client want to send a message to another client, some format must be used to send a string that is understandable by the server. When sending a string to another client, the username of the receiving client must be within the string. When the server receives the string, it extracts the username of the receiving client's username and locates the client in the Map by its key. As mentioned, the value of the Map element is the socket instance of the client you want to send to.
To make all of this possible, a thread must be used for each client that listens for input from each client.
I'm using channel-adapters (not gateways) to send data with MessagingTemplate's sendAndReceive from spring integration server to a connected nonspring client (or just telnet).
After receiving the data in the client, somewhen I want to reply data to the server and resolve that sendAndReceive-Waiting. I still want to be able to send other data to the server.
How will sendAndReceive detect a response? Right now I can send whatever I want to the server, it will assume it as a new incoming message.
Is there a predefined way, like prefixing a messageid or do I have to implement it manually by interpreting the incoming messages and somehow "resolve" the sendAndReceive-blocker?
MessagingTemplate.sendAndReceive is based on the TemporaryReplyChannel which is placed to the MessageHeaders and afterward some AbstractReplyProducingMessageHandler just uses that header to send reply back.
Yes, the sending Thread is blocked to wait for the reply throughout that TemporaryReplyChannel.
Hope that can help you a bit.
All other your comment regarding TCP/IP isn't clear for me yet...
I want to send data to my connected clients, but I want to send the message only to one specific user. I don't know how to accomplish this. Do I have to use the client's IP address or what? I'm programming in Java with sockets.
you need to add connected connection in some collection.
Socket client = serverSocket.accept();
map.put("someKey", client);
when you have to send message to any specific client. just get his connection from map by giving its key.
Socket clnt = map.get("someKey");
// further processing.
in c# you can use dictionary in place of maps.
You have to keep track of the clients that connect to your server. Most likely using a client ID with a Key/Value collection (try looking up Map).
I'm trying to make a port of a chat program a friend of mine made with lacewing and multimedia fusion 2 for android device.
I've managed to create a socket connecting to the listening socket of the server successfully, but I cannot seem to be able to send data to login and enter the chat. The login for now just requires a name, but even if I send a String of data, the server doesn't seem to reply or accept that data to get me over the channel.
I know I could easily port this with other way like using the NDK of the multimedia fusion 2 exporter, but I just want to figure out how this works
PS: I'm using Java and libgdx for the development
You need to read the liblacewing relay protocol:
https://github.com/udp/lacewing/blob/0.2.x/relay/current_spec.txt
On initial connection, you have to send byte 0 to identify that you are not an HTTP client. After this, you can exchange normal protocol messages.
The first message you need to send is the connection request (which may be denied by the server with a deny message). This would be:
byte 0 (2.1.0 request)
(1.2 size)
byte 0 (2.1.0.0 connection request)
string "revision 3" (2.1.0.0 connection request -> version)
When the server responds with response 0 (2.2.0.0 Connect), you then have to set a name before you may join any channels. This is done with message 2.1.0.1 SetName, which is the same structure as above but instead of 2.1.0.0's byte 0, it is 2.1.0.1's byte 1, followed by the name as a string instead of the protocol version.
The server should then respond with 2.2.0.1 SetName, assuming it accepted your name change request. You should process this message in case the server gave you a different name than you requested. Finally, once you have a name, you can join a channel with 2.1.0.2 JoinChannel. The flags you specify here will be used if the channel doesn't exist yet (e.g. nobody is in the chat yet) - these should match the ones in the MMF2 project file. The name should also match.
After all that, you're still not done! You have to process more messages, etc. it's almost like writing the RelayClient class yourself. It's a tough task, but with the protocol specification in hand you should be able to work it all out.
I am trying to create a client socket connection, when a new request is created a connection is established & data transfer takes place. Is there any way that once the Connection is created it will be open for all time ? If yes then how can create it & also how can I identify what request is sent & got the response for the same request?
Looking forward for your response.
You can create a connection for all time, by not closing it. However the trick is detecting when a connection has failed. e.g. the client/server has restarted.
If you want to match requests to responses you can use a request id, but a much simpler approach is to only send one request at a time per socket, that way the response you get is for the request you just sent. You can use more than one socket in a thread if this is required.