RavenApiController.cs

using System;
using System.Net.Http;
using System.Threading;
using System.Threading.Tasks;
using System.Web.Http;
using System.Web.Http.Controllers;
using Raven.Client;
using Raven.Client.Document;

namespace Webinars.Controllers
{
	public abstract class RavenApiController : ApiController
	{
		public static Lazy<IDocumentStore> DocumentStore = new Lazy<IDocumentStore>(() =>
			{
				var docStore = new DocumentStore
					{
						Url = "http://localhost:8080",
						DefaultDatabase = "Webinars"
					};
				docStore.Initialize();

				return docStore;
			});

		private IDocumentSession session;
		public IAsyncDocumentSession asyncSession;

		public override async Task<HttpResponseMessage> ExecuteAsync(
			HttpControllerContext controllerContext,
			CancellationToken cancellationToken)
		{
			var result = await base.ExecuteAsync(controllerContext, cancellationToken);
			if (session != null)
				session.SaveChanges();
			if (asyncSession != null)
				await asyncSession.SaveChangesAsync();
			return result;
		}

		public IDocumentSession Session
		{
			get
			{
				if (asyncSession != null)
					throw new NotSupportedException("Can't use both sync & async sessions in the same action");
				return session ?? (session = DocumentStore.Value.OpenSession());
			}
			set { session = value; }
		}

		public IAsyncDocumentSession AsyncSession
		{
			get
			{
				if (session != null)
					throw new NotSupportedException("Can't use both sync & async sessions in the same action");
				return asyncSession ?? (asyncSession = DocumentStore.Value.OpenAsyncSession());
			}
			set { asyncSession = value; }
		}
	}
}

Webinar.cs

using System;
using System.Collections.Generic;

namespace Webinars.Models
{
	public class Webinar
	{
		public string Id { get; set; } 
		public DateTimeOffset ScheduledAt { get; set; }
		public string Presenter { get; set; }
		public List<string> Tags { get; set; }
		public string Description { get; set; }

		public Webinar()
		{
			Tags = new List<string>();
		}
	}
}

WebinarsController.cs

using System;
using System.Threading.Tasks;
using System.Web.Http;
using Webinars.Models;

namespace Webinars.Controllers
{
	public class WebinarsController : RavenApiController
	{
		[HttpGet]
		 public async Task<string> Create(string presenter,[FromUri] string[] tags, string desc)
		 {
			 var webinar = new Webinar
				 {
					 Description = desc,
					 ScheduledAt = DateTime.Today.AddDays(7),
					 Presenter = presenter,
				 };
			 webinar.Tags.AddRange(tags);
			 await AsyncSession.StoreAsync(webinar);

			 return webinar.Id;
		 }

		 [HttpGet]
		 public Webinar Load(int id)
		 {
			 return Session.Load<Webinar>(id);
		 }
	}
}