Hi Jahan,

so your controller should look something like this:

[PluginController("ReplyApi")]
public class ReplyApiController : UmbracoAuthorizedJsonController
{
     [HttpPost]
     public bool ReplyMessage(string message)
     {
         //Send your message here
         //Maybe return if it was a success - thus the bool return value, can also be void or what you need
     }
}

Also your controller is in the wrong place. AppPlugins only contains all the angularjs stuff. Instead put it in AppCode or in a Controller folder in your solution.

Second the path to your api controller is wrong. I would suggest to use ServerVariables for these kind of paths.

You can add ServerVariables during application startup:

public class StartUp : IApplicationEventHandler
{
     public void OnApplicationStarted(UmbracoApplicationBase umbracoApplication, ApplicationContext applicationContext)
     {
            ServerVariablesParser.Parsing += ServerVariablesParser_Parsing;
     }

void ServerVariablesParser_Parsing(object sender, Dictionary<string, object> e)
        {
            if(HttpContext.Current == null) throw new InvalidOperationException("HttpContext is null");
            var urlHelper = new UrlHelper(new RequestContext(new HttpContextWrapper(HttpCo

ntext.Current), new RouteData()));

        var dict = new Dictionary<string, object>();

        dict.Add("replyBaseUrl", urlHelper.GetUmbracoApiServiceBaseUrl<ReplyApiController>(controller => controller.ReplyMessage("")));

        if (!e.Keys.Contains("replyController"))
        {
            e.Add("replyController", dict);
        }
    }
}

With that you can use the path in your angular controller like so:

Umbraco.Sys.ServerVariables.replyController.replyBaseUrl

So your http call will look like this:

$http.post(Umbraco.Sys.ServerVariables.replyController.replyBaseUrl + "ReplyMessage?message=" + textMessage) // Can not find this URL
        .then(function (response) {
            alert("YES!");
            //TODO: 
        });

Hope that helps