/// <summary>
/// Add an observer for the given observable resource
/// </summary>
/// <param name="coapReq">A request message from client that is requesting resource observation</param>
public void AddResourceObserver(CoAPRequest coapReq)
{
if (coapReq == null)
{
throw new ArgumentNullException("CoAP message requesting for observation is NULL");
}
if (!coapReq.IsObservable())
{
throw new ArgumentException("CoAP message requesting for observation is not marked as observable");
}
string observableURL = coapReq.GetURL().Trim().ToLower();
//First, add this URL as an observable resource
this.AddObservableResource(observableURL);
//Now, add this observer for the given observable resource
this._observableListSync.WaitOne();
bool observerAlreadyExists = false;
ArrayList observers = (ArrayList)this._observers[observableURL];
for (int count = 0; count < observers.Count; count++)
{
CoAPRequest storedObserver = (CoAPRequest)observers[count];
if (storedObserver.ID.Value == coapReq.ID.Value)
{
observerAlreadyExists = true;
break;
}
}
if (!observerAlreadyExists)
{
observers.Add(coapReq);
}
this._observableListSync.Set();
}
/// <summary>
/// Send the CoAP message to client
/// </summary>
/// <param name="coapMsg">The CoAP message to send</param>
/// <returns>Number of bytes sent</returns>
public override int Send(AbstractCoAPMessage coapMsg)
{
if (coapMsg == null)
{
throw new ArgumentNullException("Message is NULL");
}
if (this._socket == null)
{
throw new InvalidOperationException("CoAP server not yet started");
}
int bytesSent = 0;
try
{
//We do not want server to die when a socket send error occurs...
//just clean all settings specific to the remote client and
//keep going
byte[] coapBytes = coapMsg.ToByteStream();
bytesSent = this._socket.SendTo(coapBytes, coapMsg.RemoteSender);
if (coapMsg.MessageType.Value == CoAPMessageType.CON)
{
//confirmable message...need to wait for a response
coapMsg.DispatchDateTime = DateTime.Now;
this._msgPendingAckQ.AddToWaitQ(coapMsg);
}
}
catch (Exception e)
{
this._msgPendingAckQ.RemoveFromWaitQ(coapMsg.ID.Value);
if (coapMsg.GetType() == typeof(CoAPRequest))
{
CoAPRequest coapReq = (CoAPRequest)coapMsg;
this._observers.RemoveResourceObserver(coapReq.GetURL(), coapReq.Token.Value);
}
else if (coapMsg.GetType() == typeof(CoAPResponse))
{
CoAPResponse coapResp = (CoAPResponse)coapMsg;
this._observers.RemoveResourceObserver(coapResp);
}
this.HandleError(e, coapMsg);
}
return(bytesSent);
}
/// <summary>
/// Called when a CoAP request is received...we will only support CON requests
/// of type GET... the path is sensors/temp
/// </summary>
/// <param name="coapReq">CoAPRequest object</param>
static void OnCoAPRequestReceived(CoAPRequest coapReq)
{
string reqPath = (coapReq.GetPath() != null) ? coapReq.GetPath().ToLower() : "";
/*We have skipped error handling in code below to just focus on observe option*/
if (coapReq.MessageType.Value == CoAPMessageType.CON && coapReq.Code.Value == CoAPMessageCode.GET)
{
if (!coapReq.IsObservable() /*Does the request have "Observe" option*/)
{
/*Request is not to observe...we do not support anything no-observable*/
CoAPResponse resp = new CoAPResponse(CoAPMessageType.ACK,
CoAPMessageCode.NOT_IMPLEMENTED,
coapReq /*Copy all necessary values from request in the response*/);
coapServer.Send(resp);
}
else if (!coapServer.ObserversList.IsResourceBeingObserved(coapReq.GetURL()) /*do we support observation on this path*/)
{
//Observation is not supported on this path..just to tell you how to check
CoAPResponse resp = new CoAPResponse(CoAPMessageType.ACK,
CoAPMessageCode.NOT_FOUND,
coapReq /*Copy all necessary values from request in the response*/);
coapServer.Send(resp);
}
else
{
//This is a request to observe this resource...register this client
coapServer.ObserversList.AddResourceObserver(coapReq);
/*Request contains observe option and path is correct*/
CoAPResponse resp = new CoAPResponse(CoAPMessageType.ACK,
CoAPMessageCode.EMPTY,
coapReq /*Copy all necessary values from request in the response*/);
//send it..tell client we registered it's request to observe
coapServer.Send(resp);
}
}
}
/// <summary>
/// Based on the token value, find which resource was being observed
/// </summary>
/// <param name="token">The CoAP token that is used for req/resp matching</param>
/// <returns>The URL of the resource being observed</returns>
protected string FindResourceBeingObserved(CoAPToken token)
{
if (token == null || token.Value == null)
{
throw new ArgumentNullException("Invalid token");
}
bool observerFound = false;
string observedResourceURL = null;
CoAPRequest observerEntry = null;
this._observableListSync.WaitOne();
foreach (string observedResURL in this._observers.Keys)
{
ArrayList observers = (ArrayList)this._observers[observedResURL];
foreach (CoAPRequest req in observers)
{
if (AbstractByteUtils.AreByteArraysEqual(req.Token.Value, token.Value))
{
observerFound = true;
observerEntry = req;
break;
}
}
if (observerFound)
{
break;
}
}
this._observableListSync.Set();
if (observerFound && observerEntry != null)
{
observedResourceURL = observerEntry.GetURL();
}
return(observedResourceURL);
}