CoAP response does not contain a definition of remote sender

Question

I am trying to make a CoAP NON server using CoAPSharp binary in Visual Studio 2015. My target device is Raspberry Pi with Windows IoT core.

"Remotesender" part has the error. I don't know how to solve it

/// <summary>
/// Called when a request is received
/// </summary>
/// <param name="coapReq">The CoAPRequest object</param>
void OnCoAPRequestReceived(CoAPRequest coapReq)
{
    //This sample only works on NON requests of type GET
    //This sample simualtes a temperature sensor at the path "sensors/temp"

    string reqURIPath = (coapReq.GetPath() != null) ? coapReq.GetPath    ().ToLower() : "";
/**
        * Draft 18 of the specification, section 5.2.3 states, that if     against a NON message,
        * a response is required, then it must be sent as a NON message
        */
    if (coapReq.MessageType.Value != CoAPMessageType.NON)
    {
        //only NON  combination supported..we do not understand this send a RST back
        CoAPResponse msgTypeNotSupported = new CoAPResponse    (CoAPMessageType.RST, /*Message type*/
                                                            CoAPMessageCode.NOT_IMPLEMENTED, /*Not implemented*/
                                                            coapReq.ID.Value /*copy message Id*/);
        msgTypeNotSupported.Token = coapReq.Token; //Always match the     request/response token
        msgTypeNotSupported.RemoteSender = coapReq.RemoteSender;
        //send response to client
        this._coapServer.Send(msgTypeNotSupported);
    }
    else if (coapReq.Code.Value != CoAPMessageCode.GET)
    {
        //only GET method supported..we do not understand this send a RST back
        CoAPResponse unsupportedCType = new CoAPResponse    (CoAPMessageType.RST, /*Message type*/
                                        CoAPMessageCode.METHOD_NOT_ALLOWED, /*Method not allowed*/
                                        coapReq.ID.Value /*copy message Id*/);
        unsupportedCType.Token = coapReq.Token; //Always match the request/response token
        unsupportedCType.RemoteSender = coapReq.RemoteSender;
        //send response to client
        this._coapServer.Send(unsupportedCType);
}
    else if (reqURIPath != "sensors/temp")
{
        //classic 404 not found..we do not understand this send a RST back 
        CoAPResponse unsupportedPath = new CoAPResponse    (CoAPMessageType.RST, /*Message type*/
                                            CoAPMessageCode.NOT_FOUND, /*Not found*/
                                            coapReq.ID.Value /*copy message Id*/);
        unsupportedPath.Token = coapReq.Token; //Always match the     request/response token
        unsupportedPath.RemoteSender = coapReq.RemoteSender;
        //send response to client
        this._coapServer.Send(unsupportedPath);
    }
    else
    {
        //All is well...send the measured temperature back
    //Again, this is a NON message...we will send this message as a JSON
    //string
    Hashtable valuesForJSON = new Hashtable();
    valuesForJSON.Add("temp", this.GetRoomTemperature());
    string tempAsJSON = JSONResult.ToJSON(valuesForJSON);
    //Now prepare the object
    CoAPResponse measuredTemp = new CoAPResponse(CoAPMessageType.NON, /*Message type*/
                                        CoAPMessageCode.CONTENT, /*Carries content*/
                                        coapReq.ID.Value/*copy message Id*/);
    measuredTemp.Token = coapReq.Token; //Always match the request/response token
    //Add the payload
    measuredTemp.Payload = new CoAPPayload(tempAsJSON);
    //Indicate the content-type of the payload
    measuredTemp.AddOption(CoAPHeaderOption.CONTENT_FORMAT,
                        AbstractByteUtils.GetBytes(CoAPContentFormatOption.APPLICATION_JSON));
    //Add remote sender address details
    measuredTemp.RemoteSender = coapReq.RemoteSender;
    //send response to client
    this._coapServer.Send(measuredTemp);
}
}

Error:

error: CS1061 C# does not contain a definition for and no extension method accepting a first argument of type could be found (are you missing a using directive or an assembly reference?)

Simply following the tutorial on CoAPSharp official website.

Answer 1

If you want to run the CoAPSharp library on Raspberry Pi with Windows 10 IoT core, you need to download the experimental release for Windows 10 IoT core. The URL is http://www.coapsharp.com/releases/ . See the last download link.

Also, you may want yo get the source and recompile to get the latest binary to reference in your main project.

Additional information added on 3-Nov-16: OK, I understood what the problem is. Here is a full and large answer :-)

1. The CoAPSharp experimental library has a small bug (although unrelated to your problem). I am one of the CoAPSharp developers and work for the company which built the library. The updated library with the fix should be available in a day or two. The issue was with synchronous receive.

2. The sample you are trying to run, is for NETMF and not for Windows 10 IoT Core and that is why you are getting the errors. There are no samples for the Raspberry Pi experimental release. To help you with the problem, I'm giving below step-by-step solution:

3. First, download the latest CoAPSharp experimental library to get the fix for synchronous receive bug.

4. Next, create a solution in which, create one UWA project and add the CoAPSharp library to the solution. Reference the library in the UWA project.

5.1 Create a small server code for Raspberry Pi in this project, as shown below:

    /// <summary>
    /// We will start a server locally and then connect to it
    /// </summary>
    private void TestLocalCoAPServer()
    {
        /*_coapServer variable is a class level variable*/
        _coapServer = new CoAPServerChannel();
        _coapServer.CoAPRequestReceived += OnCoAPRequestReceived;
        _coapServer.Initialize(null, 5683);
    }
    /// <summary>
    /// Gets called everytime a CoAP request is received
    /// </summary>
    /// <param name="coapReq">The CoAP Request object instance</param>
    private async void OnCoAPRequestReceived(CoAPRequest coapReq)
    {
        //send ACK back
        Debug.WriteLine("Received Request::" + coapReq.ToString());
        CoAPResponse coapResp = new CoAPResponse(CoAPMessageType.ACK, CoAPMessageCode.CONTENT, coapReq);
        coapResp.AddPayload("GOT IT!");
        await _coapServer.Send(coapResp);
    }

5.2 Next, ensure that port 5683 is not blocked on Raspberry Pi. If yes, then use the powershell to unblock it.

5.3 Next, create a new solution on your desktop(I used Windows 10 and Visual Studio 2015 Community edition) and add another copy of CoAPSharp Raspberry Pi experimental library.

5.3 Now create another UWA project on your desktop . Also, refer the CoAPSharp project in this new project.

5.4 Now write a client in this project that will send/receive CoAP messages from the server hosted on the Raspberry Pi:

    private async void TestCoAPAsyncClient()
    {
        /*_coapAsyncClient is declared at class level*/
        this._coapAsyncClient = new CoAPClientChannel();
        /*minwinpc was the name of the device running Windows IoT core on Raspberry Pi*/
        this._coapAsyncClient.Initialize("minwinpc", 5683);
        this._coapAsyncClient.CoAPError += delegate (Exception e, AbstractCoAPMessage associatedMsg) {
            Debug.WriteLine("Exception e=" + e.Message);
            Debug.WriteLine("Associated Message=" + ((associatedMsg != null) ? associatedMsg.ToString() : "NULL"));
        };
        this._coapAsyncClient.CoAPRequestReceived += delegate (CoAPRequest coapReq) {
            Debug.WriteLine("REQUEST RECEIVED !!!!!!!!!!!!!!" + coapReq.ToString());
        };
        this._coapAsyncClient.CoAPResponseReceived += delegate (CoAPResponse coapResp) {
            Debug.WriteLine("RESPONSE RECEIVED <<<<<<<<<<<<<" + coapResp.ToString());
        };

        CoAPRequest req = new CoAPRequest(CoAPMessageType.CON, CoAPMessageCode.GET, 100);
        //req.SetURL("coap://capi.coapworks.com:5683/v1/time/pcl?mid=CPWK-TESTM");
        req.SetURL("coap://localhost:5683/someurl");
        await this._coapAsyncClient.Send(req);
    }

6. You can call the method TestCoAPAsyncClient() in a button click or when the page is loaded.

7. The setup I used was, one desktop with Windows 10 and Visual Studio Community Edition 2015. This was connected to Raspberry Pi running Windows 10 IoT core (OS: 10.0.10240.16384). Both my desktop and the Raspberry Pi were connected to ethernet.

CoAPSharp team added a sample at the link http://www.coapsharp.com/coap-server-windows-10-iot-core-raspberry-pi/ to elaborate this further.