/// <summary>
/// What is the result of the this request?
/// The method will keep waiting/requesting an answer till the answer is received or the timeout is reached
/// </summary>
/// <param name="message">The request</param>
/// <param name="timeOut">The time to wait in milliseconds, 0 means forever</param>
/// <returns>The result, null in the case an answer isn't received</returns>
public object SendRequest(object message, long timeOut)
{
Contract.Requires(message != null);
Contract.Requires(timeOut >= 0);
// Send a request
this.requestId++;
Packet packet = new Packet("server", this.name, this.requestId.ToString(), message);
this.udpMulticast.Send(packet);
// Start listening for a reply
long preTime = DateTime.Now.ToFileTime();
// Test if the timeout is 0 or the timeout value has run out
while (timeOut == 0 || DateTime.Now.ToFileTime() < preTime + (timeOut * 10000)) {
// Wait for reply
object result = this.udpMulticast.Receive(500);
if (result == null) {
// No reply - resend...
Debug.WriteLine("Client repeats");
this.udpMulticast.Send(packet);
}
else if (result is Packet) {
// A packet was received
Packet recPacket = (Packet)result;
// Test if the packet is for us
if (recPacket.GetReceiverId.Equals(this.name) && recPacket.GetRequestId.Equals(this.requestId.ToString())) {
return recPacket.GetMessage;
}
}
}
// The timeout value has expired
return null;
}
/// <summary>
/// Listen for calls for this amount of time
/// If a request with the same request id is repeated, the reply is repeated
/// </summary>
/// <param name="timeOut">The time to wait in miliseconds</param>
public void ListenForCalls(long timeOut)
{
Contract.Requires(timeOut >= 0);
Contract.Requires(this.RequestHandler != null);
// If the server should listen for requests forever
bool runForever = timeOut == 0;
// The time before the loop was entered
long preTime = DateTime.Now.ToFileTime();
// Listen
while (runForever || DateTime.Now.ToFileTime() < preTime + (timeOut * 10000)) {
// Receive the packet
object data;
if (runForever) {
// The udpMulticast is allowed to block forever
data = this.udpMulticast.Receive(0);
}
else {
// The udpMulticast is allowed to block for the time left
long timeLeft = ((preTime + (timeOut * 10000)) - DateTime.Now.ToFileTime()) / 10000;
data = this.udpMulticast.Receive(timeLeft);
}
// Test if it's a valid packet
if (data == null || !(data is Packet)) {
continue;
}
// Test if the packet is for the server
Packet recPacket = (Packet)data;
if (recPacket.GetReceiverId.Equals("server")) {
// If the packet has been received before
if (this.prevPackets.ContainsKey(recPacket.GetSenderId + "#" + recPacket.GetRequestId)) {
// Repeat the reply
this.udpMulticast.Send(this.prevPackets[recPacket.GetSenderId + "#" + recPacket.GetRequestId]);
}
else {
// The package has not been seen before and we need to generate a response
Console.Out.WriteLine("Server sends fresh");
string senderId = recPacket.GetSenderId;
string requestId = recPacket.GetRequestId;
object resultMessage = this.RequestHandler.Invoke(recPacket.GetMessage);
Packet resultPacket = new Packet(senderId, "server", requestId, resultMessage);
// Add this request and reply to the list of previous packets
this.prevPackets.Add(recPacket.GetSenderId + "#" + recPacket.GetRequestId, resultPacket);
this.udpMulticast.Send(resultPacket);
}
}
}
}
