Using Camunda with .NET

This is a tutorial how to interacte with Camunda BPM within a .NET Core application. Camunda BPM is an open source workflow engine written in Java. The engine offers a Java-API, but also a very good documentated REST-API. You can implement your own REST-Client or generate it from the provided OpenApi description. The Camunda.OpenApi.Client Nuget package includes a pre-buildet generated Camunda REST-Client from the OpenApi description. You don't have to take care about the generatation of the REST-Client, you can just use it. You can have a look at the Github Repo to see how the generatation of the REST-Client works.

You can add the Nuget Package to your project:

Install-Package Camunda.OpenApi.Client -Version 1.0.1

After that you can define your own extension to add this later over Dependency-Injection:

public static class CamundaClientExtension
    {
        public static void AddCamundaClient(this IServiceCollection services)
        {
            var config = new Configuration
            {
                BasePath = "http://localhost:8080/engine-rest",
                UserAgent = "CamundaClient"
            };

            // add all needed api's
            services.AddSingleton(new TaskApi(config));
            services.AddSingleton(new TaskVariableApi(config));
            services.AddSingleton(new ProcessInstanceApi(config));
            services.AddSingleton(new ProcessDefinitionApi(config));
            services.AddSingleton(new DeploymentApi(config));
            services.AddSingleton(new MessageApi(config));
            services.AddSingleton(new HistoricProcessInstanceApi(config));
            services.AddSingleton(new HistoricActivityInstanceApi(config));
        }
    }

Add services.AddCamundaClient(); in Startup.cs on the ConfigureServices method:

public void ConfigureServices(IServiceCollection services)
{
    services.AddControllers();
    services.AddCamundaClient();
    services.AddSwaggerGen(c =>
    {
        c.SwaggerDoc("v1", new OpenApiInfo {Title = "TestWebApp", Version = "v1"});
    });
}

Now you can inject the api services everywhere in your application. For example in a ApiController:

[ApiController]
[Route("[controller]")]
public class ExampleController : ControllerBase
{
    private readonly TaskApi _taskApi;

    public ExampleController(TaskApi taskApi)
    {
        _taskApi = taskApi;
    }

    [HttpGet]
    public IEnumerable<TaskDto> Get()
    {
        return _taskApi.QueryTasks();
    }
}

Comments

[Nicklas Wessel]

It would be helpful if you could introduce what it is in the beginning.
I'm still clueless to what this package can do for me or what it is at all :)

Also, you have just copy/pasted everything from github. I'm confused

[Silvan]

The idea is that not everyone need to care about generating the REST-Client itself. So you can just use the pre-buildet Nuget package. And yes it's more or less the same as on github. This blog post should be a oppertunity for me to share my project further.

[Nicklas Wessel]

I think it is fine to share your project.
But i think it would be good to explain what Camunda is, or link to their page, since i thought your project was Camunda, and I'm still not sure what problem it solves.

We need some background :) the project looks cool though