22 replies to this topic

[kenNET]

Hi, Can I connect to a webservice (developed in .NET) and get/post as I do with a regular C# windows application? Thanks!

[Chris Walker]

Hi kenNET, You can call web services, but you'll need to parse the results manually. There might be a component for this, but I'm not sure if it will fit on small microcontrollers like Netduino. Chris

[Fred]

You should be able to, but you'll have to do the work of constructing the HTTP request yourself. Keep it simple. If you're not committed to a web service already I'd suggest looking at something like MVC so you just need to construct a URL or a basic HTTP post on the Netduino. If you do get it working please let us all know how it went.

[kenNET]

Thanks for your quick answers. I think I will go for a simple http post to a regular .aspx webpage where I just return commaseparate data, this will reduce data and is easy to parse. Now I just wait for the netduino Plus to be on sale, I want one now ;-) /Ken

[Osi]

Hello

I used socketclient sample from .Net Microframework SDK to call a web service. There is a better way I'm sure, but I'm newbie and I wanted to port my Arduino code fast.

It works.

Regards,
Mark

using System;
using System.Text;
using System.Net;
using System.Net.Sockets;
using System.Threading;
using Microsoft.SPOT;
using Microsoft.SPOT.Hardware;
using SecretLabs.NETMF.Hardware;
using SecretLabs.NETMF.Hardware.NetduinoPlus;
using Socket = System.Net.Sockets.Socket;

namespace NetduinoPlus_Temperature_Logger
{
    public class Program
    {
        static OutputPort led = new OutputPort(Pins.ONBOARD_LED, false);
        static bool pressing = false;
        static string httpserver = "10.146.104.211";
        static Int32 httpport = 81;
        static string SensorID = "000000000000000000000000000000000001";

        public static void Main()
        {
            InterruptPort button = new InterruptPort(Pins.ONBOARD_SW1, false, Port.ResistorMode.Disabled, Port.InterruptMode.InterruptEdgeBoth);
            button.OnInterrupt += new NativeEventHandler(button_OnInterrupt);
            while (true)
            {
                if (!pressing)
                {
                    led.Write(true);
                    Thread.Sleep(250);
                    led.Write(false);
                    Thread.Sleep(250);
                }
            }
        }

        static void button_OnInterrupt(uint data1, uint data2, DateTime time)
        {
            pressing = data2 == 0;
            String request = "POST /SensorService.asmx HTTP/1.1\n";
            request += "Host: " + httpserver + "\n";
            request += "Content-Type: text/xml; charset=utf-8\n";
            request += "Content-Length: 418\n";
            request += "SOAPAction: \"http://" + httpserver + "/StoreData\"\n\n";
            request += "<?xml version=\"1.0\" encoding=\"utf-8\"?>\n";
            request += "<soap:Envelope xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\" xmlns:soap=\"http://schemas.xmlsoap.org/soap/envelope/\">\n";
            request += "<soap:Body>\n";
            request += "<StoreData xmlns=\"http://" + httpserver + "/\">\n";
            request += "<password>upstempdata</password>\n";
            request += "<Value>";
            request += "22.22";
            request += "</Value>\n";
            request += "<SensorID>";
            request += SensorID;
            request += "</SensorID>\n";
            request += "</StoreData>\n";
            request += "</soap:Body>\n";
            request += "</soap:Envelope>\n\n";
            try
            {
                String html = Post(httpserver, httpport, request);
                Debug.Print(html);
            }
            catch (SocketException se)
            {
                Debug.Print("SocketException when connecting to " + httpserver + ":" + httpport);
                Debug.Print("If your network uses IPSec, you may need enable the port manually");
                Debug.Print("Socket Error Code: " + se.ErrorCode.ToString());
                Debug.Print(se.ToString());
            }
        }

        /// <summary>
        /// Issues a http POST request on the specified server.
        /// </summary>
        /// <param name="server"></param>
        /// <param name="port"></param>
        /// <param name="request"></param>
        /// <returns></returns>
        private static String Post(String server, Int32 port, String request)
        {
            const Int32 c_microsecondsPerSecond = 1000000;

            // Create a socket connection to the specified server and port.
            using (Socket serverSocket = ConnectSocket(server, port))
            {
                // Send request to the server.
                Byte[] bytesToSend = Encoding.UTF8.GetBytes(request);
                serverSocket.Send(bytesToSend, bytesToSend.Length, 0);

                // Reusable buffer for receiving chunks of the document.
                Byte[] buffer = new Byte[1024];

                // Accumulates the received page as it is built from the buffer.
                String page = String.Empty;

                // Wait up to 30 seconds for initial data to be available.  Throws an exception if the connection is closed with no data sent.
                DateTime timeoutAt = DateTime.Now.AddSeconds(30);
                while (serverSocket.Available == 0 && DateTime.Now < timeoutAt)
                {
                    System.Threading.Thread.Sleep(100);
                }

                // Poll for data until 30-second timeout.  Returns true for data and connection closed.
                while (serverSocket.Poll(30 * c_microsecondsPerSecond, SelectMode.SelectRead))
                {
                    // If there are 0 bytes in the buffer, then the connection is closed, or we have timed out.
                    if (serverSocket.Available == 0) break;

                    // Zero all bytes in the re-usable buffer.
                    Array.Clear(buffer, 0, buffer.Length);

                    // Read a buffer-sized HTML chunk.
                    Int32 bytesRead = serverSocket.Receive(buffer);

                    // Append the chunk to the string.
                    page = page + new String(Encoding.UTF8.GetChars(buffer));
                }

                // Return the complete string.
                return page;
            }
        }

        /// <summary>
        /// Creates a socket and uses the socket to connect to the server's IP address and port.
        /// </summary>
        /// <param name="server"></param>
        /// <param name="port"></param>
        /// <returns></returns>
        private static Socket ConnectSocket(String server, Int32 port)
        {
            // Get server's IP address.
            IPHostEntry hostEntry = Dns.GetHostEntry(server);

            // Create socket and connect to the server's IP address and port
            Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
            socket.Connect(new IPEndPoint(hostEntry.AddressList[0], port));
            return socket;
        }
    }
}

[Carsten Dressler]

I'd suggest you use a RESTful web service instead of a .NET (SOAP/XML) Web Service.

RESTful web services use basic HTTP GET/POST commands to process stuff. Normally the data returned is a JSON format (alot easier to work with compared to XML).

You can create a WCF RESTFul web services using IIS or selfhosted (exe).

Here is a Self-Hosted Web Service:

Imports System.ServiceModel
Imports System.ServiceModel.Channels
Imports System.ServiceModel.Web

<ServiceContract()> _
Public Class WCF

    <OperationContract()> _
    <WebGet(RequestFormat:=WebMessageFormat.Json, UriTemplate:="add&a={A1}&b={B1}")> _
    Public Function Add(ByVal A1 As String, ByVal B1 As String) As Integer
        Return A1 + B1
    End Function

End Class

Imports System
Imports System.ServiceModel
Imports System.ServiceModel.Description

Module Program

    Private _WS As servicehost

    Sub Main()

        Dim _uri As New Uri("http://" + Environment.MachineName + ":81/Pool")

        _WS = New ServiceHost(GetType(WCF), _uri)
        Dim ep As ServiceEndpoint = _WS.AddServiceEndpoint(GetType(WCF), New WebHttpBinding, String.Empty)
        ep.Behaviors.Add(New WebHttpBehavior)

        _WS.Open()

        Console.WriteLine("Ready")
        Console.Read()

    End Sub

End Module

Then to call the web service, you can use your web broswer to test. For example

http://hostname:81/P...ool/add?a=1&b=2

Hope that makes since....

[Carsten Dressler]

BTW, you could call the RESTful web service like this from the Netduino:

  HttpWebRequest myReq = (HttpWebRequest)WebRequest.Create("http://xxx:81/Pool/add?a=1&b=4");
  myReq.Method = "GET";
  HttpWebResponse WebResp = (HttpWebResponse)myReq.GetResponse();

[alum]

BTW, you could call the RESTful web service like this from the Netduino:

  HttpWebRequest myReq = (HttpWebRequest)WebRequest.Create("http://xxx:81/Pool/add?a=1&b=4");
  myReq.Method = "GET";
  HttpWebResponse WebResp = (HttpWebResponse)myReq.GetResponse();

I can't import HttpWebRequest. Are you sure this is possible?

[Chris Walker]

I can't import HttpWebRequest. Are you sure this is possible?

Have you added the System.Net.Http.dll assembly as a reference to your project (or equivalent)?

Chris

[alum]

Of course! Thanks alot! No need for socket programming! yay!

[Hector Cubillos]

An unhandled exception of type 'System.Net.WebException' occurred in System.Http.dll please help me

[NeonMika / Markus VV.]

An unhandled exception of type 'System.Net.WebException' occurred in System.Http.dll
please help me

Could you show us the code area in which this exception is thrown?

[Hans75]

BTW, you could call the RESTful web service like this from the Netduino:

  HttpWebRequest myReq = (HttpWebRequest)WebRequest.Create("http://xxx:81/Pool/add?a=1&b=4");
  myReq.Method = "GET";
  HttpWebResponse WebResp = (HttpWebResponse)myReq.GetResponse();

Does anyone have an complete example of this?.. I cant get it to work..(been fiddling all weekend..), managed to get a REST webservice on asp.net up and running,
but cant read it with my netduino.

[nakchak]

That's pretty much all their is to it, however that snippet you posted is using port 81 not port 80. Also have you opened the relevant ports on your windows firewall? By default you need to allow all traffic on port 80 (for http) to your windows box for your web service to connect Nak.

[Hans75]

That's pretty much all their is to it, however that snippet you posted is using port 81 not port 80.

Also have you opened the relevant ports on your windows firewall?

By default you need to allow all traffic on port 80 (for http) to your windows box for your web service to connect

Nak.

guess port 80, for http, is always open.. thats not my issue...
i am struggling and confused with all the drivers/dll to be used, and how they relate to each other..
System.Net, System.Net.Sockets System.Threading Microsoft.SPOT Microsoft.SPOT.Hardware, SecretLabs.NETMF.Hardware SecretLabs.NETMF.Hardware.NetduinoPlus?

i was getting close.. i get the message that .GetResponse is not recognized.. and should be .GetBeginResponse which, after googling, opened a few pages of additional code i dont understand.

[nakchak]

Check that inbound port 80 is allowed, outbound port 80 is always open, but inbound is nearly always closed unless you have explicitly opened it.
Where is the computer located that you are trying to connect to?

If you want a simple to use HTTP client for your netduino i would recommend the one in Stefan's netmf toolbox. Then you can use simple code like this:

using System;
using System.IO.Ports;
using System.Threading;
using Microsoft.SPOT;
using Microsoft.SPOT.Hardware;
using Microsoft.SPOT.Net.NetworkInformation;
using SecretLabs.NETMF.Hardware.NetduinoPlus;
using Toolbox.NETMF.NET;
namespace HTTPClient {
 public class Program {
  var webClient = new HttpClient(new IntegratedSocket(http://xxx, 80));
  var response = webClient.Get("/Pool/add?a=1&b=4");
  if(response.ResponseCode != 200) {
	Debug.Print("Invalid Response");
  }
  Debug.Print(response.ResponseBody);
  Thread.Sleep(Timeout.Infinite);
 }
}

Nak.

[Hans75]

Check that inbound port 80 is allowed, outbound port 80 is always open, but inbound is nearly always closed unless you have explicitly opened it.
Where is the computer located that you are trying to connect to?

If you want a simple to use HTTP client for your netduino i would recommend the one in Stefan's netmf toolbox. Then you can use simple code like this:

using System;
using System.IO.Ports;
using System.Threading;
using Microsoft.SPOT;
using Microsoft.SPOT.Hardware;
using Microsoft.SPOT.Net.NetworkInformation;
using SecretLabs.NETMF.Hardware.NetduinoPlus;
using Toolbox.NETMF.NET;
namespace HTTPClient {
 public class Program {
  var webClient = new HttpClient(new IntegratedSocket(http://xxx, 80));
  var response = webClient.Get("/Pool/add?a=1&b=4");
  if(response.ResponseCode != 200) {
	Debug.Print("Invalid Response");
  }
  Debug.Print(response.ResponseBody);
  Thread.Sleep(Timeout.Infinite);
 }
}

Nak.

I still have the same issue::
using System;
using System.IO.Ports;
using System.Threading;
using Microsoft.SPOT;
using Microsoft.SPOT.Hardware;
using Microsoft.SPOT.Net.NetworkInformation;
using SecretLabs.NETMF.Hardware.NetduinoPlus;
using Toolbox.NETMF.NET;

namespace HTTPClient {

public class Readservice {
public static void Main()
{
var webClient = new HttpClient(new IntegratedSocket("http://xxx, 80"));

it cant find HttpClient!
Error 1 The type or namespace name 'HttpClient' could not be found (are you missing a using directive or an assembly reference?)
Error 2 The type or namespace name 'IntegratedSocket' could not be found (are you missing a using directive or an assembly reference?) E:\VS2010\Netduino\georgiposted\Readserver.cs

in the Toolbox.NETMF.NET there is a only a Http_Client...

[Stefan]

in the Toolbox.NETMF.NET there is a only a Http_Client...

Interesting, I can't recall I renamed that class once. But it should be HTTP_Client indeed.

[Hans75]

Interesting, I can't recall I renamed that class once. But it should be HTTP_Client indeed.

And Integratedsocket renamed itself into SimpleSocket?

[Stefan]

And Integratedsocket renamed itself into SimpleSocket?

Nope, SimpleSocket is an interface, Integratedsocket follows that interface.

The reason for that interfacing is to also support managed network drivers, like the wifly driver. As explained here