// .split try to call a service
// Here, we first check if the requested MDP service is defined or not,
// using a MMI lookup to the Majordomo broker. If the service exists,
// we send a request and wait for a reply using the conventional MDP
// client API. This is not meant to be fast, just very simple:
static bool Titanic_ServiceSuccess(Guid uuid, CancellationTokenSource cts)
{
// Load request message, service will be first frame
string fn = TitanicCommon.RequestFilename(uuid);
FileStream fs;
if (!fn.TryFileOpenRead(out fs))
{
// If the client already close request, treat as successful
return(true);
}
fs.Dispose();
ZMessage request = fn.DeserializeFromXml <ZMessage>();
var service = request.Pop();
string servicename = service.ToString();
bool res = false;
// Create MDP client session with short timeout
using (var client = new MajordomoClient("tcp://127.0.0.1:5555", false))
{
client.Set_Timeout(1000); // 1sec
client.Set_Retries(1); // only 1 retry
// Use MMI protocol to check if service is available
ZMessage mmirequest = new ZMessage {
service
};
bool service_ok;
using (var mmireply = client.Send("mmi.service", mmirequest, cts))
service_ok = (mmireply != null &&
mmireply.First().ToString().Equals("200"));
res = false;
if (service_ok)
{
using (ZMessage reply = client.Send(servicename, request, cts))
if (reply != null)
{
fn = TitanicCommon.ReplyFilename(uuid);
reply.SerializeToXml(fn);
res = true;
}
else
{
request.Dispose();
}
}
}
return(res);
}
// .split Titanic request service
// The {{titanic.request}} task waits for requests to this service. It writes
// each request to disk and returns a UUID to the client. The client picks
// up the reply asynchronously using the {{titanic.reply}} service:
private static void Titanic_Request(ZContext ctx, ZSocket backendpipe, CancellationTokenSource cancellor, object[] args)
{
using (MajordomoWorker worker = new MajordomoWorker("tcp://127.0.0.1:5555", "titanic.request", (bool)args[0]))
{
ZMessage reply = null;
while (true)
{
// Send reply if it's not null
// And then get next request from broker
ZMessage request = worker.Recv(reply, cancellor);
if (request == null)
{
break; // Interrupted, exit
}
// Ensure message directory exists
Directory.CreateDirectory(TitanicCommon.TITANIC_DIR);
// Generate UUID and save mesage to disk
Guid uuid = TitanicCommon.GenerateUuid();
string fn = TitanicCommon.RequestFilename(uuid);
request.SerializeToXml(fn);
request.Dispose();
// Send UUID through tho message queue
reply = new ZMessage();
reply.Add(new ZFrame(uuid.ToString()));
ZError error;
if (!backendpipe.Send(reply, out error))
{
if (error.Equals(ZError.ETERM))
{
break;
}
}
//backendpipe.Send(reply);
// Now send UUID back to client
// Done by the mdwrk_recv() at the top of the loop
reply = new ZMessage();
reply.Add(new ZFrame("200"));
reply.Add(new ZFrame(uuid.ToString()));
}
}
}
// .split Titanic close task
// The {{titanic.close}} task removes any waiting replies for the request
// (specified by UUID). It's idempotent, so it is safe to call more than
// once in a row:
private static void Titanic_Close(ZContext context, CancellationTokenSource cts, bool verbose)
{
using (var worker = new MajordomoWorker("tcp://127.0.0.1:5555", "titanic.close", verbose))
{
ZMessage reply = null;
while (true)
{
ZMessage request = worker.Recv(reply, cts);
if (request == null)
{
break;
}
var g = Guid.Parse(request.Pop().ReadString());
var reqfn = TitanicCommon.RequestFilename(g);
var repfn = TitanicCommon.ReplyFilename(g);
File.Delete(reqfn);
File.Delete(repfn);
request.Dispose();
reply = new ZMessage();
reply.Add(new ZFrame("200"));
}
}
}
// .split Titanic reply service
// The {{titanic.reply}} task checks if there's a reply for the specified
// request (by UUID), and returns a 200 (OK), 300 (Pending), or 400
// (Unknown) accordingly:
private static void Titanic_Reply(ZContext context, CancellationTokenSource cts, bool verbose)
{
using (var worker = new MajordomoWorker("tcp://127.0.0.1:5555", "titanic.reply", verbose))
{
ZMessage reply = null;
while (true)
{
var request = worker.Recv(reply, cts);
if (request == null)
{
break; // Interrupted, exit
}
var g = Guid.Parse(request.Pop().ReadString());
var reqfn = TitanicCommon.RequestFilename(g);
var repfn = TitanicCommon.ReplyFilename(g);
if (File.Exists(repfn))
{
reply = repfn.DeserializeFromXml <ZMessage>();
reply.Prepend(new ZFrame("200"));
}
else
{
reply = new ZMessage();
if (File.Exists(reqfn))
{
reply.Prepend(new ZFrame("300")); //Pending
}
else
{
reply.Prepend(new ZFrame("400")); //Unknown
}
}
request.Dispose();
}
}
}