How to use ZMQ when Server on IP other than the client - zeromq

Question

I learned how to use ZeroMQ on a localhost, but I failed to do it on a remote IP.
Q1: Do I need a broker?If so,Q2: which broker and how to do it.?
Update:
OK. I'm using the ZMQ Weather Update example but with a remote IP ( not the localhost ). Here is what I do using C# ZMQ bindings ( however, I'm OK to use any other language ):
ZMQ Server:
using (var context = new ZContext())
using (var publisher = new ZSocket(context, ZSocketType.PUB))
{
string address = "tcp://*:5001";
publisher.Bind(address);
publisher.Send("msg")
}
Proxy:
using (var context = new ZContext())
using (var frontend = new ZSocket(context, ZSocketType.XSUB))
using (var backend = new ZSocket(context, ZSocketType.XPUB))
{
// Frontend is where the weather server sits
string localhost = "tcp://127.0.0.1:5001";
Console.WriteLine("I: Connecting to {0}", localhost);
frontend.Connect(localhost);
// Backend is our public endpoint for subscribers
string remoteIP = "216.123.23.98"; // For example
var tcpAddress = string.Format("tcp://{0}:8100", remoteIP); // I also tried localhost address here
Console.WriteLine("I: Binding on {0}", tcpAddress);
backend.Bind(tcpAddress);
var epgmAddress = string.Format("epgm://localhost;{0}:8100", remoteIP);
Console.WriteLine("I: Binding on {0}", epgmAddress);
backend.Bind(epgmAddress);
using (var subscription = ZFrame.Create(1))
{
subscription.Write(new byte[] { 0x1 }, 0, 1);
backend.Send(subscription);
}
// Run the proxy until the user interrupts us
ZContext.Proxy(frontend, backend);
}
Client:
using (var context = new ZContext())
using (var subscriber = new ZSocket(context, ZSocketType.SUB))
{
string remoteIP = "tcp://216.123.23.98"; //For example
Console.WriteLine("I: Connecting to {0}…", remoteIP);
subscriber.Connect(connect_to);
// Subscribe to zipcode
string zipCode = args[0];
Console.WriteLine("I: Subscribing to zip code {0}…", zipCode);
subscriber.Subscribe(zipCode);
// Process 10 updates
int i = 0;
long total_temperature = 0;
for (; i < 20; ++i)
{
ZError err;
using (var replyFrame = subscriber.ReceiveFrame(out err))
{
string reply = replyFrame.ReadString(Encoding.ASCII);
Console.WriteLine(reply);
total_temperature += Convert.ToInt64(reply.Split(' ')[1]);
}
}
Console.WriteLine("Average temperature for zipcode '{0}' was {1}", zipCode, (total_temperature / i));
}
When I run this I get error in Server and error in proxy - server gets
Invalid end point
and proxy gets EINVAL(22):
Invalid argument at ZeroMQ.ZSocket.Bind(String endpoint)

Answer 1

A1: No, ZeroMQ is a Broker-less messaging framework.
A2: N/A
How to repair the code?
All the services need to obey respective transport-class addressing rules, for the TCP/IP case - both the .bind() / .connect() methods have to state both parts of the IP:PORT# specification ( with some aids from DNS-resolution for the IP-part, but the :PORT#-part is still mandatory )
( which the source-code does not meet in client, ref.:
subscriber.Connect(connect_to);
whereas there ought be also a Proxy-side matching :PORT#, i.e.:8100, specified, for a correct .connect() ).
For the clarity and for avoiding a port#-collision, remove the epgm transport class from the code.