CoAP.NET - A CoAP library for .NET

The Constrained Application Protocol (CoAP) (https://datatracker.ietf.org/doc/draft-ietf-core-coap/) is a RESTful web transfer protocol for resource-constrained networks and nodes. CoAP.NET is an implementation in C# providing CoAP-based services to .NET applications. Reviews and suggestions would be appreciated.

Copyright

Copyright (c) 2011-2013, Longxiang He <[email protected]>, SmeshLink Technology Co.
Copyright (c) 2016-2020, Jim Schaad <[email protected]>
Copyright (c) 2023-, Stephen Berard <[email protected]>

How to Install

The C# implementation is available in the NuGet Package Gallery under the name CoAP.NET. To install this library as a NuGet package, enter 'Install-Package CoAP.NET' in the NuGet Package Manager Console.

Documentation

Coming soon

CoAP Client

Access remote CoAP resources by issuing a Request and receive its Response(s).

  // new a GET request
  Request request = new Request(Method.GET);
  request.URI = new Uri("coap://[::1]/hello-world");
  request.Send();
  
  // wait for one response
  Response response = request.WaitForResponse();

There are 4 types of request: GET, POST, PUT, DELETE, defined as Method.GET, Method.POST, Method.PUT, and Method.DELETE.

Responses can be received in two ways. By calling request.WaitForResponse() a response will be received synchronously, which means it will block until timeout or a response is arrived. If more responses are expected, call WaitForResponse() again.

To receive responses asynchronously, register a event handler to the event request.Respond before executing.

Parsing Link Format

Use LinkFormat.Parse(String) to parse a link-format response. The returned enumeration of WebLink contains all resources stated in the given link-format string.

  Request request = new Request(Method.GET);
  request.URI = new Uri("coap://[::1]/.well-known/core");
  request.Send();
  Response response = request.WaitForResponse();
  IEnumerable<WebLink> links = LinkFormat.Parse(response.PayloadString);

See CoAP Example Client for more.

CoAP Server

A new CoAP server can be easily built with help of the class CoapServer

  static void Main(String[] args)
  {
    CoapServer server = new CoapServer();
    
    server.Add(new HelloWorldResource("hello"));
    
    server.Start();
    
    Console.ReadKey();
  }

See CoAP Example Server for more.

CoAP Resource

CoAP resources are classes that can be accessed by a URI via CoAP. In CoAP.NET, a resource is defined as a subclass of Resource. By overriding methods DoGet, DoPost, DoPut, or DoDelete, one resource accepts GET, POST, PUT or DELETE requests.

The following code gives an example of HelloWorldResource, which can be visited by sending a GET request to "/hello-world", and respones a plain string in code "2.05 Content".

  class HelloWorldResource : Resource
  {
      public HelloWorldResource()
          : base("hello-world")
      {
          Attributes.Title = "GET a friendly greeting!";
      }

      protected override void DoGet(CoapExchange exchange)
      {
          exchange.Respond("Hello World from CoAP.NET!");
      }
  }
  
  class Server
  {
      static void Main(String[] args)
      {
          CoapServer server = new CoapServer();
          server.Add(new HelloWorldResource());
          server.Start();
      }
  }

See CoAP Example Server for more.

Logging

Logging makes use of the Microsoft.Extensions.Logging package. Logging is configured using the static LogManager class. By default, logs will be output to the console. A custom logger can be specified by calling LogManager.SetLoggerFactory(ILoggerFactory) as follows:

var loggerFactory = LoggerFactory.Create(builder =>
{
    builder.AddConsole();
});
LogManager.SetLoggerFactory(loggerFactory);

Building the sources

The project is built using Visual Studio 2022. The project is set up to use the latest .NET framework (version 7.0 as of this writing). The project can be built direction in Visual Studio or via the the command line as follows:

> dotnet build

License

BSD with attribution See LICENSE for more info.

Acknowledgements

This project is built on the CoAP-CSharp project of jimsch and the CoAP.NET project of smeshlink (which in turn is based on Eclipse Californium). This is a refresh of the original codebases as they were both no longer being maintained.
The package and class names have been reset to the original names per the CoAP.NET project.