CODEWITHSUNDEEP
c#udponvifdevice-discovery
Steve Blomeley
Steve Blomeley

Reputation: 95

C# Onvif discovery request - responses sent from networked cameras are not received

We're trying to get a basic Onvif discovery C# program to discover cameras on a local network. We can discover the cameras using an off the shelf tool, like Onvif Device Manager. Using Wireshark, we can see the UDP requests that Onvif DM sends out, and the responses from the cameras.

When we run our basic Onvif discovery console app, Wireshark shows us almost identical UDP requests being broadcast, and within 1 second we can see responses on the network from the 3 cameras. But our application does not see the responses: our DiscoveryClient FindProgressChanged event handler is never invoked, and the collection of Endpoints returned by the DiscoveryClient's Find method is empty.

Here's our Discovery console app:

using System;
using System.ServiceModel.Discovery;
using System.Xml;

namespace DiscoveryClient
{
    public class Program
    {
        public static void Main(string[] args)
        {
            var endPoint = new UdpDiscoveryEndpoint(DiscoveryVersion.WSDiscoveryApril2005);

            var discoveryClient = new System.ServiceModel.Discovery.DiscoveryClient(endPoint);

            discoveryClient.FindProgressChanged += DiscoveryClient_FindProgressChanged;

            var findCriteria = new FindCriteria
            {
                Duration = TimeSpan.FromSeconds(10),
                MaxResults = int.MaxValue
            };

            findCriteria.ContractTypeNames.Add(new XmlQualifiedName("NetworkVideoTransmitter", @"http://www.onvif.org/ver10/network/wsdl"));

            Console.WriteLine("Initiating find operation.");
            var response = discoveryClient.Find(findCriteria);
            Console.WriteLine($"Operation returned - Found {response.Endpoints.Count} endpoints.");

            Console.ReadKey();
        }

        private static void DiscoveryClient_FindProgressChanged(object sender, FindProgressChangedEventArgs e)
        {
            Console.WriteLine($"Found this: {e}");
        }
    }
}

And here's an example UDP discovery request generated by the App (the only difference between this, and a request generated by Onvif DM is the Duration element within the Probe)

<s:Envelope xmlns:s="http://www.w3.org/2003/05/soap-envelope" xmlns:a="http://schemas.xmlsoap.org/ws/2004/08/addressing">
<s:Header>
    <a:Action s:mustUnderstand="1">http://schemas.xmlsoap.org/ws/2005/04/discovery/Probe</a:Action>
    <a:MessageID>urn:uuid:3445e6a6-0751-4953-9071-394ab3f85fcb</a:MessageID>
    <a:ReplyTo><a:Address>http://schemas.xmlsoap.org/ws/2004/08/addressing/role/anonymous</a:Address></a:ReplyTo>
    <a:To s:mustUnderstand="1">urn:schemas-xmlsoap-org:ws:2005:04:discovery</a:To>
</s:Header>
<s:Body>
    <Probe xmlns="http://schemas.xmlsoap.org/ws/2005/04/discovery">
        <d:Types xmlns:d="http://schemas.xmlsoap.org/ws/2005/04/discovery" xmlns:dp0="http://www.onvif.org/ver10/network/wsdl">dp0:NetworkVideoTransmitter</d:Types>
        <Duration xmlns="http://schemas.microsoft.com/ws/2008/06/discovery">PT10S</Duration>
    </Probe>
</s:Body>

Any ideas as to what's going on here - why does our application not see the responses to it's discovery request?

Upvotes: 2

Views: 1305

Answers (0)

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