//
// Load-balancing broker in C#
//
// Clients and workers are shown here in-process.
// While this example runs in a single process, that is just to make
// it easier to start and stop the example. Each thread may have its own
// context and conceptually acts as a separate process.
//
// Author: metadings
//
// Basic request-reply client using REQ socket
static void LBBroker_Client(ZContext context, int i)
{
// Create a socket
using (var client = new ZSocket(context, ZSocketType.REQ))
{
// Set a printable identity
client.IdentityString = "CLIENT" + i;
// Connect
client.Connect("inproc://frontend");
using (var request = new ZMessage())
{
request.Add(new ZFrame("Hello"));
// Send request
client.Send(request);
}
// Receive reply
using (ZMessage reply = client.ReceiveMessage())
{
reply.DumpZmsg("---Client received from broker---");
Console.WriteLine("CLIENT{0}: {1}", i, reply[0].ReadString());
}
}
}
public void SendToBroker(string command, string option, ZMessage msg)
{
using (msg = msg != null ? msg.Duplicate() : new ZMessage())
{
if (!string.IsNullOrEmpty(option))
msg.Prepend(new ZFrame(option));
msg.Prepend(new ZFrame(command));
msg.Prepend(new ZFrame(MdpCommon.MDPW_WORKER));
msg.Prepend(new ZFrame(string.Empty));
if (Verbose)
msg.DumpZmsg("I: sending '{0:X}|{0}' to broker", command.ToMdCmd());
Worker.Send(msg);
}
}
public void SendToBroker(string command, string option, ZMessage msg)
{
using (msg = msg != null ? msg.Duplicate() : new ZMessage())
{
if (!string.IsNullOrEmpty(option))
{
msg.Prepend(new ZFrame(option));
}
msg.Prepend(new ZFrame(command));
msg.Prepend(new ZFrame(MdpCommon.MDPW_WORKER));
msg.Prepend(new ZFrame(string.Empty));
if (Verbose)
{
msg.DumpZmsg("I: sending '{0:X}|{0}' to broker", command.ToMdCmd());
}
Worker.Send(msg);
}
}
// .until
// .skip
// The send method now just sends one message, without waiting for a
// reply. Since we're using a DEALER socket we have to send an empty
// frame at the start, to create the same envelope that the REQ socket
// would normally make for us:
public int Send(string service, ZMessage request, CancellationTokenSource cancellor)
{
if (request == null)
{
throw new NotImplementedException();
}
if (cancellor.IsCancellationRequested ||
(Console.KeyAvailable && Console.ReadKey(true).Key == ConsoleKey.Escape))
{
_context.Shutdown();
}
// Prefix request with protocol frames
// Frame 0: empty (REQ emulation)
// Frame 1: "MDPCxy" (six bytes, MDP/Client x.y)
// Frame 2: Service name (printable string)
request.Prepend(new ZFrame(service));
request.Prepend(new ZFrame(MdpCommon.MDPC_CLIENT));
request.Prepend(new ZFrame(string.Empty));
if (Verbose)
{
request.DumpZmsg("I: send request to '{0}' service:", service);
}
ZError error;
if (!Client.Send(request, out error))
{
;
}
{
if (Equals(error, ZError.ETERM))
{
cancellor.Cancel(); // Interrupted
}
//throw new ZException(error);
}
return(0);
}
public static void Identity(string[] args)
{
//
// Demonstrate request-reply identities
//
// Author: metadings
//
using (var context = new ZContext())
using (var sink = new ZSocket(context, ZSocketType.ROUTER))
{
sink.Bind("inproc://example");
// First allow 0MQ to set the identity
using (var anonymous = new ZSocket(context, ZSocketType.REQ))
{
anonymous.Connect("inproc://example");
anonymous.Send(new ZFrame("ROUTER uses REQ's generated 5 byte identity"));
}
using (ZMessage msg = sink.ReceiveMessage())
{
msg.DumpZmsg("--------------------------");
}
// Then set the identity ourselves
using (var identified = new ZSocket(context, ZSocketType.REQ))
{
identified.IdentityString = "PEER2";
identified.Connect("inproc://example");
identified.Send(new ZFrame("ROUTER uses REQ's socket identity"));
}
using (ZMessage msg = sink.ReceiveMessage())
{
msg.DumpZmsg("--------------------------");
}
}
}
// .split worker send method
// This method formats and sends a command to a worker. The caller may
// also provide a command option, and a message payload:
public void Send(string command, string option, ZMessage msg)
{
msg = msg != null
? msg.Duplicate()
: new ZMessage();
// Stack protocol envelope to start of message
if (!string.IsNullOrEmpty(option))
{
msg.Prepend(new ZFrame(option));
}
msg.Prepend(new ZFrame(command));
msg.Prepend(new ZFrame(MdpCommon.MDPW_WORKER));
// Stack routing envelope to start of message
msg.Wrap(Identity.Duplicate());
if (Broker.Verbose)
{
msg.DumpZmsg("I: sending '{0:X}|{0}' to worker", command.ToMdCmd());
}
Broker.Socket.Send(msg);
}
static void Main(string[] args)
{
//
// Demonstrate request-reply identities
//
// Author: metadings
//
using (var context = new ZContext())
using (var sink = new ZSocket(context, ZSocketType.ROUTER))
{
sink.Bind("inproc://example");
// First allow 0MQ to set the identity
using (var anonymous = new ZSocket(context, ZSocketType.REQ))
{
anonymous.Connect("inproc://example");
anonymous.Send(new ZFrame("ROUTER uses REQ's generated 5 byte identity"));
ZMessage msg = sink.ReceiveMessage();
msg.DumpZmsg("-------------anonymous-------------");
using (msg)
using (ZMessage newMsg = new ZMessage())
{
//send three frame, but the client received is the only data frame, it's the 3rd frame.
newMsg.Add(msg[0]);
newMsg.Add(new ZFrame());
newMsg.Add(new ZFrame("router to REQ"));
sink.Send(newMsg);
}
using (ZMessage routerMsg = anonymous.ReceiveMessage())
{
routerMsg.DumpZmsg("-------------anonymous-------------");
}
}
// Then set the identity ourselves
using (var identified = new ZSocket(context, ZSocketType.REQ))
{
identified.IdentityString = "PEER2";
identified.Connect("inproc://example");
identified.Send(new ZFrame("ROUTER uses REQ's socket identity"));
ZMessage msg = sink.ReceiveMessage();
msg.DumpZmsg("------------identified--------------");
using (msg)
using (ZMessage newMsg = new ZMessage())
{
//send three frame, but the client received is the only data frame, it's the 3rd frame.
newMsg.Add(msg[0]);
//here, this is very important. If we do not add the empty frame, client will receive nothing.
newMsg.Add(new ZFrame());
newMsg.Add(new ZFrame("router to REQ"));
sink.Send(newMsg);
}
using (ZMessage routerMsg = identified.ReceiveMessage())
{
routerMsg.DumpZmsg("-------------identified-------------");
}
}
using (var DEALERIdentify = new ZSocket(context, ZSocketType.DEALER))
{
DEALERIdentify.Connect("inproc://example");
DEALERIdentify.Send(new ZFrame("ROUTER uses Dealer's generated 5 byte identity, But there is no empty frame as separeator"));
ZMessage msg = sink.ReceiveMessage();
msg.DumpZmsg("------------DEALERIdentify--------------");
using (msg)
using (ZMessage newMsg = new ZMessage())
{
//send three frame, but the client received is the only data frame, it's the 3rd frame.
newMsg.Add(msg[0]);
//here, this is very important. That there is no separeator for Dealer!!!!!!!!!!!!!!, If we add the empty frame, it will be treat as data frame
//newMsg.Add(new ZFrame());
newMsg.Add(new ZFrame("router to REQ"));
sink.Send(newMsg);
}
using (ZMessage routerMsg = DEALERIdentify.ReceiveMessage())
{
routerMsg.DumpZmsg("-------------DEALERIdentify-------------");
}
}
}
Console.WriteLine();
Console.WriteLine("Press any key to exit...");
Console.ReadLine();
}
// .split worker send method
// This method formats and sends a command to a worker. The caller may
// also provide a command option, and a message payload:
public void Send(string command, string option, ZMessage msg)
{
msg = msg != null
? msg.Duplicate()
: new ZMessage();
// Stack protocol envelope to start of message
if (!string.IsNullOrEmpty(option))
msg.Prepend(new ZFrame(option));
msg.Prepend(new ZFrame(command));
msg.Prepend(new ZFrame(MdpCommon.MDPW_WORKER));
// Stack routing envelope to start of message
msg.Wrap(Identity.Duplicate());
if(Broker.Verbose)
msg.DumpZmsg("I: sending '{0:X}|{0}' to worker", command.ToMdCmd());
Broker.Socket.Send(msg);
}
// .split broker worker_msg method
// This method processes one READY, REPLY, HEARTBEAT, or
// DISCONNECT message sent to the broker by a worker:
public void WorkerMsg(ZFrame sender, ZMessage msg)
{
if(msg.Count < 1) // At least, command
throw new InvalidOperationException();
ZFrame command = msg.Pop();
//string id_string = sender.ReadString();
bool isWorkerReady;
//string id_string;
using (var sfrm = sender.Duplicate())
{
var idString = sfrm.Read().ToHexString();
isWorkerReady = Workers.ContainsKey(idString);
}
Worker worker = RequireWorker(sender);
using (msg)
using (command)
{
if (command.StrHexEq(MdpCommon.MdpwCmd.READY))
{
if (isWorkerReady)
// Not first command in session
worker.Delete(true);
else if (command.Length >= 4
&& command.ToString().StartsWith("mmi."))
// Reserd servicee name
worker.Delete(true);
else
{
// Attach worker to service and mark as idle
using (ZFrame serviceFrame = msg.Pop())
{
worker.Service = RequireService(serviceFrame);
worker.Service.Workers++;
worker.Waiting();
}
}
}
else if (command.StrHexEq(MdpCommon.MdpwCmd.REPLY))
{
if (isWorkerReady)
{
// Remove and save client return envelope and insert the
// protocol header and service name, then rewrap envelope.
ZFrame client = msg.Unwrap();
msg.Prepend(new ZFrame(worker.Service.Name));
msg.Prepend(new ZFrame(MdpCommon.MDPC_CLIENT));
msg.Wrap(client);
Socket.Send(msg);
worker.Waiting();
}
else
{
worker.Delete(true);
}
}
else if (command.StrHexEq(MdpCommon.MdpwCmd.HEARTBEAT))
{
if (isWorkerReady)
{
worker.Expiry = DateTime.UtcNow + MdpCommon.HEARTBEAT_EXPIRY;
}
else
{
worker.Delete(true);
}
}
else if (command.StrHexEq(MdpCommon.MdpwCmd.DISCONNECT))
worker.Delete(false);
else
{
msg.DumpZmsg("E: invalid input message");
}
}
}
// .split send request and wait for reply
// Here is the {{send}} method. It sends a request to the broker and gets
// a reply even if it has to retry several times. It takes ownership of
// the request message, and destroys it when sent. It returns the reply
// message, or NULL if there was no reply after multiple attempts:
public ZMessage Send(string service, ZMessage request, CancellationTokenSource cancellor)
{
if (request == null)
{
throw new InvalidOperationException();
}
// Prefix request with protocol frames
// Frame 1: "MDPCxy" (six bytes, MDP/Client x.y)
// Frame 2: Service name (printable string)
request.Prepend(new ZFrame(service));
request.Prepend(new ZFrame(MdpCommon.MDPC_CLIENT));
if (Verbose)
{
request.DumpZmsg("I: send request to '{0}' service:", service);
}
int retriesLeft = Retries;
while (retriesLeft > 0 && !cancellor.IsCancellationRequested)
{
if (cancellor.IsCancellationRequested ||
(Console.KeyAvailable && Console.ReadKey(true).Key == ConsoleKey.Escape))
{
_context.Shutdown();
}
// Copy the Request and send on Client
ZMessage msgreq = request.Duplicate();
ZError error;
if (!Client.Send(msgreq, out error))
{
if (Equals(error, ZError.ETERM))
{
cancellor.Cancel();
break; // Interrupted
}
}
var p = ZPollItem.CreateReceiver();
ZMessage msg;
// .split body of send
// On any blocking call, {{libzmq}} will return -1 if there was
// an error; we could in theory check for different error codes,
// but in practice it's OK to assume it was {{EINTR}} (Ctrl-C):
// Poll the client Message
if (Client.PollIn(p, out msg, out error, Timeout))
{
// If we got a reply, process it
if (Verbose)
{
msg.DumpZmsg("I: received reply");
}
if (msg.Count < 3)
{
throw new InvalidOperationException();
}
using (ZFrame header = msg.Pop())
if (!header.ToString().Equals(MdpCommon.MDPC_CLIENT))
{
throw new InvalidOperationException();
}
using (ZFrame replyService = msg.Pop())
if (!replyService.ToString().Equals(service))
{
throw new InvalidOperationException();
}
request.Dispose();
return(msg);
}
else if (Equals(error, ZError.ETERM))
{
cancellor.Cancel();
break; // Interrupted
}
else if (Equals(error, ZError.EAGAIN))
{
if (--retriesLeft > 0)
{
if (Verbose)
{
"W: no reply, reconnecting...".DumpString();
}
ConnectToBroker();
}
else
{
if (Verbose)
{
"W: permanent error, abandoning".DumpString();
}
break; // Give up
}
}
}
if (cancellor.IsCancellationRequested)
{
"W: interrupt received, killing client...\n".DumpString();
}
request.Dispose();
return(null);
}
// .split send request and wait for reply
// Here is the {{send}} method. It sends a request to the broker and gets
// a reply even if it has to retry several times. It takes ownership of
// the request message, and destroys it when sent. It returns the reply
// message, or NULL if there was no reply after multiple attempts:
public ZMessage Send(string service, ZMessage request, CancellationTokenSource cancellor)
{
if (request == null)
throw new InvalidOperationException();
// Prefix request with protocol frames
// Frame 1: "MDPCxy" (six bytes, MDP/Client x.y)
// Frame 2: Service name (printable string)
request.Prepend(new ZFrame(service));
request.Prepend(new ZFrame(MdpCommon.MDPC_CLIENT));
if (Verbose)
request.DumpZmsg("I: send request to '{0}' service:", service);
int retriesLeft = Retries;
while (retriesLeft > 0 && !cancellor.IsCancellationRequested)
{
if (cancellor.IsCancellationRequested
|| (Console.KeyAvailable && Console.ReadKey(true).Key == ConsoleKey.Escape))
_context.Shutdown();
// Copy the Request and send on Client
ZMessage msgreq = request.Duplicate();
ZError error;
if (!Client.Send(msgreq, out error))
{
if (Equals(error, ZError.ETERM))
{
cancellor.Cancel();
break; // Interrupted
}
}
var p = ZPollItem.CreateReceiver();
ZMessage msg;
// .split body of send
// On any blocking call, {{libzmq}} will return -1 if there was
// an error; we could in theory check for different error codes,
// but in practice it's OK to assume it was {{EINTR}} (Ctrl-C):
// Poll the client Message
if (Client.PollIn(p, out msg, out error, Timeout))
{
// If we got a reply, process it
if (Verbose)
msg.DumpZmsg("I: received reply");
if(msg.Count < 3)
throw new InvalidOperationException();
using (ZFrame header = msg.Pop())
if (!header.ToString().Equals(MdpCommon.MDPC_CLIENT))
throw new InvalidOperationException();
using (ZFrame replyService = msg.Pop())
if(!replyService.ToString().Equals(service))
throw new InvalidOperationException();
request.Dispose();
return msg;
}
else if (Equals(error, ZError.ETERM))
{
cancellor.Cancel();
break; // Interrupted
}
else if (Equals(error, ZError.EAGAIN))
{
if (--retriesLeft > 0)
{
if (Verbose)
"W: no reply, reconnecting...".DumpString();
ConnectToBroker();
}
else
{
if (Verbose)
"W: permanent error, abandoning".DumpString();
break; // Give up
}
}
}
if (cancellor.IsCancellationRequested)
{
"W: interrupt received, killing client...\n".DumpString();
}
request.Dispose();
return null;
}
// .split broker worker_msg method
// This method processes one READY, REPLY, HEARTBEAT, or
// DISCONNECT message sent to the broker by a worker:
public void WorkerMsg(ZFrame sender, ZMessage msg)
{
if (msg.Count < 1) // At least, command
{
throw new InvalidOperationException();
}
ZFrame command = msg.Pop();
//string id_string = sender.ReadString();
bool isWorkerReady;
//string id_string;
using (var sfrm = sender.Duplicate())
{
var idString = sfrm.Read().ToHexString();
isWorkerReady = Workers.ContainsKey(idString);
}
Worker worker = RequireWorker(sender);
using (msg)
using (command)
{
if (command.StrHexEq(MdpCommon.MdpwCmd.READY))
{
if (isWorkerReady)
{
// Not first command in session
worker.Delete(true);
}
else if (command.Length >= 4 &&
command.ToString().StartsWith("mmi."))
{
// Reserd servicee name
worker.Delete(true);
}
else
{
// Attach worker to service and mark as idle
using (ZFrame serviceFrame = msg.Pop())
{
worker.Service = RequireService(serviceFrame);
worker.Service.Workers++;
worker.Waiting();
}
}
}
else if (command.StrHexEq(MdpCommon.MdpwCmd.REPLY))
{
if (isWorkerReady)
{
// Remove and save client return envelope and insert the
// protocol header and service name, then rewrap envelope.
ZFrame client = msg.Unwrap();
msg.Prepend(new ZFrame(worker.Service.Name));
msg.Prepend(new ZFrame(MdpCommon.MDPC_CLIENT));
msg.Wrap(client);
Socket.Send(msg);
worker.Waiting();
}
else
{
worker.Delete(true);
}
}
else if (command.StrHexEq(MdpCommon.MdpwCmd.HEARTBEAT))
{
if (isWorkerReady)
{
worker.Expiry = DateTime.UtcNow + MdpCommon.HEARTBEAT_EXPIRY;
}
else
{
worker.Delete(true);
}
}
else if (command.StrHexEq(MdpCommon.MdpwCmd.DISCONNECT))
{
worker.Delete(false);
}
else
{
msg.DumpZmsg("E: invalid input message");
}
}
}
// .until
// .skip
// The send method now just sends one message, without waiting for a
// reply. Since we're using a DEALER socket we have to send an empty
// frame at the start, to create the same envelope that the REQ socket
// would normally make for us:
public int Send(string service, ZMessage request, CancellationTokenSource cancellor)
{
if (request == null)
throw new NotImplementedException();
if (cancellor.IsCancellationRequested
|| (Console.KeyAvailable && Console.ReadKey(true).Key == ConsoleKey.Escape))
_context.Shutdown();
// Prefix request with protocol frames
// Frame 0: empty (REQ emulation)
// Frame 1: "MDPCxy" (six bytes, MDP/Client x.y)
// Frame 2: Service name (printable string)
request.Prepend(new ZFrame(service));
request.Prepend(new ZFrame(MdpCommon.MDPC_CLIENT));
request.Prepend(new ZFrame(string.Empty));
if (Verbose)
request.DumpZmsg("I: send request to '{0}' service:", service);
ZError error;
if(!Client.Send(request, out error));
{
if (Equals(error, ZError.ETERM))
cancellor.Cancel(); // Interrupted
//throw new ZException(error);
}
return 0;
}
