OK, I'm new to server-client applications, and i need some basic information, so forgive me if my question is not clear...
I want to make a chat application that would function like this:
Client A sends information to server, server sends the same information to client B, and vice versa... Think of it as of a simple chat program.
All communication is done through sockets, so i would have a server socket application, and a client socket application... I want my client application to be on my PCs and server application to be on a remote server ( it would be hosted on some free hosting websites).
My question is how do I start that server application on that remote server?
Thanks in advance!
If you are just trying to make a chat client, I don't think you would need an intermediate server. Just connect two machines using server and client sockets
SERVER:
ServerSocketChannel serverSocket;
serverSocket = ServerSocketChannel.open();
serverSocket.socket().bind()
serverSocket.socket().accept()
CLIENT:
SocketChannel clientSocket = SocketChannel.open();
clientSocket.connect();
Of course you would have to use the bind and connect functions properly. Read up on their API's
The remote server can be started manually. (If you do not have access to remote server or if you are hosting your server on some third party infrastructure, then they might have a way to do it.)
To be able to start it remotely via some program, you again need a server on the remote machine that listens to this kind of requests.
Usually, you want an application that is running all the time at your hosting provider (like a web server or perhaps inetd) to start (or embed) your application. The details will be determined by what your hosting provider provides.
If you're using plain sockets, you should look for some remote server with SSH login. You're able to start your application on the shell then, sth like:
java -jar yourapp.jar
Free hosting websites are rather targeting customers that want to host their website. In my opinion that is not the best choice for hosting a socket application.
For developing purposes, I'd stick with the local machine for the beginning. Running/testing server/client connections on the same machine is much easier as you don't have to work on two different machines, copy code, etc.
This tutorial is relatively short, but fully covers basics of Java networking. And it is right about simple chat.
Related
Heyy guys. I'm writing a chat application in java, works pretty well. But can i somehow host my Server file or the Serversocket on the web? I want to make it so my friends from other pcs can use the client and connect to the server file which is hosted on the web. Is that possible? Can i host the File/socket online?
When you run a java application that opens a ServerSocket, it opens a port on your local machine and starts listening for incoming connections. What you do with those connections is up to the implementation of the java code that you write.
The "web" is much less foreign than you are making it out to be. Your own computer can be on the web that you're talking about and people can connect to your chat service. Or you can choose to host it on something like an AWS server.
The following approach is assuming you are behind a pretty standard NAT config.
Once you run your java application, you need to make sure other computers can see you, either inside your LAN or outside on the internet. You want to start testing from as close to your computer as possible, then start expanding outward.
First you need to make sure that your computer's firewall is actually allowing connections on the port that your java application is listening on.
Opening ports in the Windows Firewall
Setting up and opening ports in Linux
Now computers on your LAN will be able to connect to your java program. Now you need to go one layer out, and port forward your router. This is much less standard so I can't help you too much, but Google can.
At this point, anyone on this internet, knowing your external ip and what port your java application is listening, can connect to your service.
If you chose to host this on an third party hosting service, you'll need to go through similar steps, but there may be slight differences that you can either ask about, or again Google is a great resource.
I'm developing a Desktop LAN base java server and client application
where a Client must login and also to pass some data to server.
assuming i have 10 clients that inserting record simultaneously to server.
which is the best approach in this kind of situation, should I use RMI for login and record insertion? or Sockets?
if sockets please provide a key idea for me to start with.
key points to consider
-Multithreading
-able to send back data on client
If you want to connect your server via internet (and/or firewalls) it is probably a hassle to do this with plain RMI. In the past I have used Java Simon for such tasks which is very easy to implement. However if you plan to support other clients than Java clients, then you should have a look at Apache Thrift or Google Protocoll Buffers
I am having difficulties understanding the difference between network mode and non-network mode terms as used when dealing with client server applications in java.
I know how to develop simple client server apps. For example I can create a client application and server application. These applications can connect to through sockets and send and receive data. I however get confused when people talk about running a server and client in standalone mode, where both the client and server use the same instance of a JVM without loop back networking involved. I have seen this happening with the java derby database.
So my main question is how do you take code that was using sockets to communicate and convert it to use the so called "standalone mode" where the client and server run as one application? I will appreciate any comments that point me to the right material.
In the so-called network mode you have to connect to a remote server, as you describe, typically through a socket and so your client asks the server to do certain task, the server carries out the task and responds to the client.
In this mode, it is customary that the client and the server will be different nodes, that is different machines, running independently.
But what if you wanted to run you client and your server in the same machine? Even in the same virtual machine? Would it make sense to go through a socket to ask your server to do something?
That would be like using Skype to chat with a friend sat right by your side, to simply ask him to go have lunch.
So, ideally, in these cases, you should be able to run your application in non-network mode. That is, instead of going through a socket, you access your sever object directly and ask it to do something for you. Since your server object is located in the same virtual machine as your client.
Evidently, for you to be able to do this, you need a good design that exposes your server functionality through an interface, and your application uses this interface to interact with the server. When you are running in network mode, you use an implementation of this server interface that uses a socket (or RMI or whatever you do for network communication). When you are in non-network mode, you get an implementation of the server object itself.
i am developing an android application in which the server side execution is done using a simple java udp program.i want to know how i can host this application because i need a static ip server to run the java program.can i run my java program in a server.is it possible if yes how?
You'll have to write a listener in some language (PHP, Java, Etc.). As for a static ip address, you can also look at a dynamic ip redirection service like no-ip;
http://www.no-ip.com/services/managed_dns/free_dynamic_dns.html
You can use a personal machine thats always online, or you can try to use a shared hosting plan that allows you to have a listening port open. A web service will likely be easier to work with than having some custom UDP/TCP connection.
I am developing an application to send, receive or update files using Socket, ServerSocket class in Java.
There is one single application which is both server as well as client. I need to get the IP addresses of all other applications running on the same Local Area Network.
How can this be done?
You should use broadcast for this.
For more details take a look here: http://docs.oracle.com/javase/tutorial/networking/datagrams/broadcasting.html