Essentially Im trying to get many many java clients connect to a socket on my ColdFusion server (Using the Socket Gateway). However before i even start to code this, Im a little confused about sockets and their performance. First of all, are sockets meant for many(1000+) clients connecting to one socket (say port 2202) on one server? How is the performance if all there waiting for is basically a ping, or something such that when these clients receive this "ping" they can go get some new data.
Thanks,
Faisal Abid
Socket is identified by following tuple,
Source IP
Source Port
Dest IP
Dest Port
Protocol (TCP or UDP)
Even 1000 clients all connect to the same port (dest port), each will get its own socket. So you will have 1000 sockets open.
It's going to be tough to maintain 1000 sockets with blocking I/O, which usually means 1000 threads. You need to use NIO. We have a server written with Mina, which can handle 2000 connections at peak.
First of all, are sockets meant for
many(1000+) clients connecting to one
socket (say port 2202) on one server
Yes, your server will open a socket on port 2202, and 1000 client will connect to it.
Server open server socket, and client will open client socket, it different.
How is the performance if all there
waiting for is basically a ping, or
something such that when these clients
receive this "ping" they can go get
some new data
On server, you use getInputStream function to get data from client, and getOutputStream function to send data to Client.
Notice: you should use Thread to process each request of client
There is nothing wrong with many socket clients that use blocking I/O (you may have a look at this article for more information about that). However, there are another approaches that can better fit your needs here:
nio;
multicasting;
Hi connecting with 1000 clients at the same time using simple java socket programming is not the perfect way. The probelm is that in fedora linux default maximum no of file can be open is 1024 and in windows it is 2048 or something like that. so in your server side you will find more than 1000 files open and after that if client will go on increaing then you will find too many files opnened error. so the better way is to use non blocking socket programming (I mean to say to use SocketChannel) Using socket channel at the same time as per i have check we can connect with 20,000 clients without any problem.
So better use nio. there is a very good book from Oreilly publication for java nio.
I have used java nio (socket channel)
Thanks
Sunil Kumar Sahoo
Related
I'm working on a BitTorrent Client and I need to setup a TCP connection for each peer. I read online that you can't set up a second active socket untill the first is closed, with a client socket.
Would setting up a multithreading server work just as well for managing each separate concretion?
I just need to read and write byte packets following the protocol to each IP/Port pair. Preferably in separate threads so multiple blocks can be downloaded across multiple torrents at the same time.
Whats the best way to approach this?
I have to write a Socket communication program to implement
Inter Process Communication.
I understand I need to have a client and server implementation.
Server implementation:
MyServerice = new ServerSocket(PortNumber);
Client and server will be on same machine so I don't want to interfere with any other running applications
How to decide which port number to use?
You can look at this table
those are mostly all, you will never know if any other external app is taking the port you have in mind, so in your case is a
Firt to come, first to serve issue
I think in implementing the websocket object, the WebSocket protocol communications typically use TCP port number 80, so environments that block non-standard internet connections by using a firewall will still pass WebSocket packets.
I have to write a program in which clients send the server some number and wait to its response, other random number. It works Infinitely-send number and wait for response and so on...
I would like to write a server which gets a lot of connections ( and creates sockets) how can I do that in effeicient way (without creating thread to every socket created)?
Is it better to open and close sockets for every request and response?
Is there a way to send answer over a socket when I don't know which one is the right socket, but I know that all the sockets starts from the same client computer and I know the port source of the client
(I thought about making sockets array)
how can I do that in effeicient way (without creating thread to every socket created)?
You are assuming without proof that a new thread per socket is inefficient. It isn't.
Is it better to open and close sockets for every request and response?
No. Take a look at the history of HTTP. The major change between 1.0 and 1.1 was the introduction of persistent connections, which was done regardless of server-side architectures.
Is there a way to send answer over a socket when I don't know which one is the right socket
I don't understand how that situation could possibly arise. The answer only makes sense in the context of a specific session, which is associated with a specific socket. If you aren't retaining that information you should be. It's just a data structure problem.
but I know that all the sockets starts from the same client computer and I know the port source of the client (I thought about making sockets array)
If you can remember the source port you can remember the socket itself. Again, this is just a data structure problem. And there is no need for the assumption/constraint that all connections are from the same client. And unless that client is multi-threaded there is no need for multiple connections from it at all.
I'm making a java program & I want this to be both as server and a client (using sockets). How is this best achieved?
If you mean that you want to both send and receive data, a single regular socket (on each computer) will do just fine. See Socket.getInputStream and Socket.getOutputStream.
The usual "server" / "client" distinction just boils down which host is listening for incoming connections, and which hosts connect to those hosts. Once the connection is setup, you can both send and receive from both ends.
If you want both hosts to listen for incoming connections, then just set up a ServerSocket and call accept on both hosts.
Related links:
Official trail: The Java™ Tutorials, Lesson: All About Sockets
If you want each station to function as a server and a client, like a p2p chat,
you should implement a thread with a ServerSocket, listening for incoming connections, and once it got a connection, open a new thread to handle it so the current one will keep on listening for new connections.
For it to be able to connect to others, simple use SocketAddress and Socket, in a different thread to try to connect to a specified server address (e.g. by a list of the user's friends)
you can find plenty of chat examples by googling.
cheers.
If you want the program to perform the same operations regardless of whether it is a server or a client for a certain connection, I could imagine handing off both the client Socket and the ServerSocket.accept()-produced socket to the same method for processing.
Have a look at jgroups it's a library that allows the creation of groups of processes whose members can send messages to each other. Another option would be to use hazelcast...
You may also look at this question.
The best way to do this is to run the server on a thread:
You run server.accept() therefore while your program is listening for a connection on that thread you can do whatever you want on the main thread, even connect to another server therefore making the program both a server & a client.
Ok so I've found out Sockets are not serializable... so I cant pass them over TCP...
My problem is I have a homework assignment where I have 10 servers that must listen on one socket(lets call it request). For input from any of x number of clients that write to that socket. Then after one of the server processes reads a message from request it must communicate with that client over its own socket...
I tried making each server socket and the request socket on the server side, then passing those to the clients when they connected to the server... but this doesn't work...
Any tips on how I might do this? Having TCP not be 1-1 is really toying with me here.
Passing a socket over a TCP connection is like trying to pass a telephone over a telephone call, or trying to fax your fax machine. What you need to do is organize another connection between the parties concerned.
EDIT: In fact your assignment as stated doesn't even make sense:
I have 10 servers that must listen on one socket(lets call it
request).
That's not even correct terminology. Servers listen at ports, not sockets, and 10 servers listening at one port is impossible. They must each have their own port.
For input from any of x number of clients that write to that socket.
See above. Clients don't write to 'that socket'. They create their own socket that is connected to the server port, and they write to that.
Then after one of the server processes reads a message from request it
must communicate with that client over its own socket
If the server has received a connection from a client it already has a socket representing its endpoint to that connection. So all the server has to do is write the response back to the same socket it read the request from.
In short you have a major terminology problem, but you don't have a software problem at all.
Passing sockets seems crazy to me. If you're trying to write a better server, you'll have a hard time beating Netty. I'd recommend giving it a look.