protected async void createActivity_Click(object sender, EventArgs e) { string accessToken = GetFromCache("AccessToken").ToString(); string requestUri = "https://www.yammer.com/api/v1/activity.json"; HttpClient client = new HttpClient(); HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Post, requestUri); request.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json")); request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", accessToken); ActivityEnvelope envelope = new ActivityEnvelope(); envelope.Activity.Actor.Name = actorName.Text; envelope.Activity.Actor.Email = actorEmail.Text; envelope.Activity.Action = "create"; envelope.Activity.Message = activityMessage.Text; envelope.Activity.OG_Object.Title = objectTitle.Text; envelope.Activity.OG_Object.Url = objectUrl.Text; string json = envelope.GetJSON(); StringContent requestContent = new StringContent(json); request.Content = requestContent; request.Content.Headers.ContentType = new MediaTypeHeaderValue("application/json"); HttpResponseMessage response = await client.SendAsync(request); XElement root = Json2Xml(await response.Content.ReadAsStringAsync()); }