public IHttpActionResult PostActivity(PostActivityModel model)
        {
            var activityIdBytes = Encoding.UTF8.GetBytes(model.ActivityId);
            var streamIdBytes = Encoding.UTF8.GetBytes(model.StreamId);

            var activity = new Activity(streamIdBytes, activityIdBytes, model.Body, null);
            WebApiApplication.ActivityRepository.Append(activity);
            return this.Ok(model.ActivityId);
        }
        public IHttpActionResult PostActivity(PostActivityModel model)
        {
            var activityIdBytes = Encoding.UTF8.GetBytes(model.ActivityId);
            var streamIdBytes   = Encoding.UTF8.GetBytes(model.StreamId);

            var activity = new Activity(streamIdBytes, activityIdBytes, model.Body, string.Empty);

            WebApiApplication.ActivityRepository.Append(activity);

            return(Ok(model.ActivityId));
        }