/// <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>
/// 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);
}
}
}
