I need to develop a client server system where I can have multiple clients communicating with one server at the same time. I want to communicate xml serialized objects and also need to send and receive other commands to invoke methods. Now, I am just starting with socket programming in C# and .Net and found that the asynchronous I/O is the way to go so that the methods dont block the execution of code. Also there are many examples of how to
make a simple client server system. So I have a basic understanding of how that works.
Anyway, what still is not clear to me is how I can set up a server which can manage connections to multiple clients?
Can I just create a new socket per connection and then store those in some kind of list?
Do I need some kind of multiplexing to achieve this?
Do I have to listen at multiple ports?
What`s the best way here?
And the other thing is if I need to develop my own protocol to differentiate between what I am actually sending over the network --> xml serialized object or a command which might be just a string encoded in ascII or something. Or would I develop my own protocol just to send these commands?
Any kind of help is apreciated! If someone knows a good book which covers this sort of stuff, let me know. Cheers
I forgot to mention that some of my clients which are supposed to communicate with my server will be pda and I therefore use the compact framework... So this might bring in some restrictions...
You may find several of my TCP/IP .NET FAQ entries helpful, particularly using a socket as a server socket, which explains how listening servers create new client connections, and XML over TCP/IP, which discusses the decisions you have to make for an XML-over-TCP/IP protocol.
I would abandon your plan to use Sockets and switch to WCF Windows Communication Foundation. It's far more elegant and is designed to do all the things you wanted, in a considerably easier and simpler way than .NET sockets.
If you want a guide of how to use it, there are a set of amazing Microsoft webcasts by Michele Leroux Bustamante that will have you up and running in no time.
Related
I am developing a winform application.I need to implement real time notifications into it.After searching a lot on the net, I have found out that it can be done using web-sockets technology.But creating sockets is also a way of creating a bidirectional connection with the server.So,can't we just create a socket connection to the server and just don't close it.So,when server has to send some notification to the client then it can do so through that socket.If Yes, then what is the need of web-sockets? And if No, then what exactly is the difference between web-sockets and sockets?
If you control the technology used on both the server and the client, I would definitely recommend using SignalR
Because:
It's dead easy to set up
Allows you to broadcast messages to virtually any number of clients
Manages keep-alive and re-connections for you
Provides an easy to use RPC style messaging pattern
Picks the best connection method for you, depending on the type of connection and client
Allows you to use javascript clients too (using a jQuery-like library)
Doing your own socket implementation for these kind of purposes is not very "2015" ;)
If you want to use sockets, the way I would go about this is to create a Listener in the client application, and for the server to send packets to this listener.
This is a good resource to help you get started
i want to write a server-client application with C#. Server app must send a message or object to client and after this message must trigger some functions in client app. What class or tech should i use? System.Net TcpClient class or .NET Remoting or other technology? Where should i begin? I am beginner at network programming. Any advise will be helpful. Thanks for reading this question and your answers.
If you are specifically dealing with a publish/subscribe scenario, I would advise using ZeromMQ (clrzmq + libzmq). ZeroMQ is extremely easy to use and very fast. You'll find plenty of C# examples, corresponding to various scenarios on the ZeroMQ site. Depending on your specific needs, you can combine ZeroMQ and OpenPGM to do pgm (tcp) or epgm (udp) multicasting.
Simply use UdpClient class. Later you can move to TCP, if you need more reliability. UDP is simplest way to send messages across network.
Try figuring out how these chat client/server apps work. It Will get you thinking in the right direction.
I have the same dilemma as the one who posted this topic, Real-time communication with WCF
except that my problem is not about games programming. I would like to know what's the best method to use to be able to have a real time communication in between two windows applications (server-client). I am using visual c++/c# to date and i would like to be able to display all the Feeds that are being received by my server to the client in real time.
I have started trying to use .NET remoting but in my continuous research, it appears that it will use SOAP-http, and might affect the speed of the communication. My server and client will communicate using the internet and .NET remoting does not permit the use of TCP Channel when communicating in between a firewall or the internet.
Your inputs will be greatly appreciated.
I guess it depends on your escenario, if you want "real-time" and you are willing to lose some packages in the process you are better with UDP, take a video conferencing tool for example, by the time you recover your slow packages you will have to move and display the next frame in the video or audio; that is a good example for the use of UDP. This is the reason why UDP is much faster than TCP.
If however, you are not willing to lose a single bit of your message, then TCP was made for you because if you lost a package the protocol will request it again to have your complete message as complete as possible.
Additionally it depends on the way the communication is being sustained, is the information flowing from one to many?, from many to many?, one to tone?
Take NetNamedPipeBinding for instance, this will be much faster process, but is only deployed in a single machine but accross processes. Whereas NetMsmqBinding will help you to build queues and it will be amazingly reliable and scalable for scenarios where your load will be a massive number of connections.
In the end, it all boils down to your concrete escenario and your business goals.
Hope it helps
If you are willing to do your own message parsing, you can use standard TCP sockets with the TcpClient and TcpListener classes. If your data is already a serializable object, you could serialize it into a text stream and just send it over the socket, deserializing it on the client side.
To get it to work over the internet, the server needs to have the port forwarded on your router, the client would just attach to the server's public IP. You would obviously need to add an exception in your firewall for this port as well.
The biggest problem with WCF and large data is setting up the streaming, by default WCF sends everything at once, which isn't practical for large files.
Lets say I have my C# app installed on 2 laptops connected to a WiFi Wireless Local Area Network.
How can these apps send messages to each other? What method or library can I use? I heard of using sockets but I have no idea how to work with these.
You could use WCF to build a communication pipe between the 2 applications. WCF encapsulates the sockets into a more manageable interface. You can start here.
Basically, you'll want to do it the same way you would in any other language. You'll open a network connection of one flavor or another (raw TCP or UDP, or a higher level protocol like HTTP) with one side acting as a server and the other acting as a client. Then each side can write data through or read data sent by the other side. It's can get pretty complicated from there. If you Google "C# Sockets" or "C# HTTP", etc, you'll find quite a few tutorials on the subject.
This is a very good article on sending C# objects (which could include whatever messages that you want to send) over a Socket connection using the Binary Formatter. Although it is not the most efficient, it is quite easy to grasp and get working.
I would like to have a client-server application written in .NET which would do following:
server is running Linux
on the server there is SQL database (mySQL) containing document URLs
What we want:
- server side would regularly crawl all URLs and create a full text index for them
- client side would be able to perform a query into this index using GUI
The client application is written in .NET using C#. Besides of searching in documents it will be able to do a lot of other things which are not described here and which are done client-side very well.
We would like to use C# for the server side as well, but we have no experience in this area. How are things like this usually done?
Clarifying question now based on some answers:
The thing which is most unclear to me is how client-server communication is usually handled. Is client and server usually using sockets, caring about details like IP addresses, ports or NAT traversal? Or are there some common frameworks and patters, which would make this transparent, and make client-server messaging or procedure calling easy? Any examples or good starting points for this? Are there some common techniques how to handle the fact a single server is required to server multiple clients at the same time?
To use c# on Linux you will need to use Mono. This is an open source implementation of the CLR specification.
Next you need to decide on how to communicate between server and client, from the lowest level of just opening a TCP/IP socket and sending bits up and down, to .Net remoting, to WCF, to exposing webservices on the server. I do not know how compleat WCF implementation is on mono, also I think you may have issue with binary remoting between mono and MS .Net .
I would suggest RPC style WebServices offer a very good solution. WebServices also have the advantage of alowing clients from other platforms to connect easily.
EDIT
In response to the clarification of the question.
I would suggest using mono/ASP.NET/WebServices on the server, if you wish to use c# on both server and client.
One assumption I have made is that you can do a client pull model, where every message is initiated by the client. Using another approach could allow the server to push events to the client. Given the client has the ability to pole the server regularly I don't consider this much of a draw back but it may be depending on the type of application you are developing.
Mono allow execution of c# (compiled to IL) on a Linux box. Mono ASP.NET allows you to use the standard ASP.NET and integrate into Apache see http://www.mono-project.com/ASP.NET and finally WebServices allow you to communicate robustly in a strongly typed manner between you client and your server.
Using this approach negates most of the issues raised in your clarification and makes them someone else's problem.
Sockets/SSL - is taken care of by standard .Net runtime on the client and Apache on the server.
IPAddress/ports/NAT traversal - Is all taken care of. DNS look up will get the servers IP. Open socket will allow the server to respond through any firewall and NAT setup.
Multiple Clients - Apache is built to handle multiple clients processing at the same time as is ASP.NET, so you should not encounter any problems there.
As many have already mentioned there are a number of thing that you have mentioned which are going to cause you pain. I'm not going to go into those, instead I will answer your original question about communication.
The current popular choice in this kind of communication is web services. These allow you to make remote calls using the HTTP protocol, and encoding the requests and responses in XML. While this method has its critics I have found it incredibly simple to get up and running, and works fine for nearly all applications.
The .NET framework has built in support for web services which can definitely be called by your client. A brief look at the mono website indicates that it has support for web services also, so writing your server in C# and running it under mono should be fine. Googling for "C# Web Service Tutorial" shows many sites which have information about how to get started, here is a random pick from those results:
http://www.codeguru.com/Csharp/Csharp/cs_webservices/tutorials/article.php/c5477
have a look at Grasshopper:
"With Grasshopper, you can use your favorite development environment from Microsoft® to deploy applications on Java-enabled platforms such as Linux"
Or see here
The ideea is to convert your app to Java and then run it on Tomcat or JBoss.
Another approach: use the Mod_AspDotNet module for Apache, as described here.
This Basic Client/Server Chat Application in C# looks like a kind of example which might be a starting point for me. Relevant .NET classes are TcpClient and TcpListener