Installing Elsa

The Elsa NuGet package provides APIs to build and execute workflows. In this section, we'll see how to install the package into a .NET project and register the appropriate services with the DI container.

Add Package

dotnet add package Elsa

Register Services

To add Elsa services to your application, add the following code to Startup.cs:

public void ConfigureServices(IServiceCollection services)
{
    services.AddElsa();
}

You can now resolve workflow services to build, load and execute workflows. For example, here's a complete Hello World console application:

using System.Threading.Tasks;
using Elsa.Activities.Console;
using Elsa.Builders;
using Elsa.Services;
using Microsoft.Extensions.DependencyInjection;

namespace Elsa.Samples.HelloWorldConsole
{
    class Program
    {
        private static async Task Main()
        {
            // Create a service container with Elsa services.
            var services = new ServiceCollection()
                .AddElsa(options => options
                    .AddConsoleActivities()
                    .AddWorkflow<HelloWorld>()) // Defined a little bit below.
                .BuildServiceProvider();
            
            // Get a workflow runner.
            var workflowRunner = services.GetRequiredService<IBuildsAndStartsWorkflow>();

            // Run the workflow.
            await workflowRunner.BuildAndStartWorkflowAsync<HelloWorld>();
        }
    }
    
    /// <summary>
    /// A basic workflow with just one WriteLine activity.
    /// </summary>
    public class HelloWorld : IWorkflow
    {
        public void Build(IWorkflowBuilder builder) => builder.WriteLine("Hello World!");
    }
}

When you run the above program, you will see the following output:

Hello World!

See the Guides section for more examples.