Create a .NET client within minutes that connects to Diffusion™ Cloud . This example creates a client that prints the value of a JSON topic to the console when the topic is updated.

1. Create a .NET project that references the DLL file that can be downloaded from the following location: Download the .NET assembly

   Diffusion.Client

   The assembly contains the interface classes and interfaces that you use when creating a control client.

   The .NET assembly is also available through NuGet.

   Use the following .NET CLI command:

   dotnet add package Diffusion.Client -v 6.11.6

2. In your project, create a C# file that uses the following packages:

   using System.Threading;
   using System.Threading.Tasks;
   using PushTechnology.ClientInterface.Client.Callbacks;
   using PushTechnology.ClientInterface.Client.Factories;
   using PushTechnology.ClientInterface.Client.Features;
   using PushTechnology.ClientInterface.Client.Features.Topics;
   using PushTechnology.ClientInterface.Client.Topics.Details;
   using PushTechnology.ClientInterface.Data.JSON;
   using static PushTechnology.ClientInterface.Examples.Runner.Program;
   using static System.Console;
   
   namespace PushTechnology.ClientInterface.Example.Consuming {
     public sealed class ConsumingJSONTopics : IExample {
   
       }
   }

3. Create a Main method.

       public sealed class SubscribingClient
       {
           public static void Main( string[] args ) {
   
           }
       }

4. In the Main method, connect to Diffusion Cloud .

           public static void Main( string[] args ) {
               // Connect anonymously
               // Replace 'host' with your hostname
               var session = Diffusion.Sessions.Open("ws://host:80");
             }

   Or you can connect securely, using Secure Sockets Layer (SSL):

               var session = Diffusion.sessions().Open("wss://host:443");

   Or you can connect with a principal and credentials if that principal is assigned a role with the read_topic permission:

               var session = Diffusion.Sessions().Principal("principal")
               .Password("password").Open("wss://host:443");

   Replace the host, principal, and password values with your own information.
5. Next, in the Main method, get the Topics feature.

           // Get the Topics feature to subscribe to topics
             var topics = session.Topics;

   The Topics feature enables a client to subscribe to a topic or fetch its state.
6. Within the subscribing client class, create an inner class that implements IValueStream for a JSON topic.
   This inner class defines the behavior that occurs when a topic that the client subscribes to is updated. In this example, the topic stream prints the topic path and the content of the update to the console.

       internal sealed class JSONStream : IValueStream<IJSON> {
   
           public void OnClose() {
               Console.WriteLine( "The subscription stream is now closed." );
           }
   
           public void OnError( ErrorReason errorReason ) {
               Console.WriteLine( "An error has occured : {0}", errorReason );
           }
   
           public void OnSubscription( string topicPath, ITopicSpecification specification ) {
               Console.WriteLine( "Client subscribed to {0} ", topicPath );
           }
   
           public void OnUnsubscription( string topicPath, ITopicSpecification specification, TopicUnsubscribeReason reason ) {
               Console.WriteLine( "Client unsubscribed from {0} : {1}", topicPath, reason );
           }
   
           public void OnValue( string topicPath, ITopicSpecification specification, IJSON oldValue, IJSON newValue ) {
               Console.WriteLine( "New value of {0} is {1}", topicPath, newValue.ToJSONString() );
           }
       }

7. Back in the Main method of the subscribing client class, use the AddStream method to associate an instance of the topic stream that you created with the topic you want to subscribe to. In this example, the topic path is "foo/counter".

             var topic = ">foo/counter";
             // Add a topic stream for 'foo/counter' and request subscription
             var jsonStream = new JSONStream();
             topics.AddStream( topic, jsonStream );
             topics.Subscribe( topic, new TopicsCompletionCallbackDefault() );

8. Use a Thread.sleep() to hold the client open for 10 minutes while the updates are received and output.

             //Stay connected for 10 minutes
             Thread.Sleep( TimeSpan.FromMinutes( 10 ) );
   
             session.Close();

9. Compile and run your client.