Timmy Kokke

public class BingModel : IBingModel

{

    // this string is used to make the actual call to the bing API. 

    // the blancs are filled in when SearchBing method is called

    const string BingRequestURL =

        "http://api.bing.net/json.aspx?AppId={0}&Version=2.2&"

        +"Market=en-US&Query={1}&Sources=web&Web.Count={2}";

    // the request is kept so it can be used to handle the response

    private WebRequest request;

    // the SearchBing method is called from the UI thread

    //(note: //you can get your AppId at http://bing.com/developers)

    public void SearchBing(string searchText, string appId)

    {

        //the blancs are filled in  

        string requestString = 

            string.Format(BingRequestURL, 

                          appId, 

                          HttpUtility.UrlEncode(searchText),

                          20); //20 results will be givin.

        //a new request is made.

        request = HttpWebRequest.Create(requestString);

        //the getting of the response is started. The OnRequestCompleted 

        //method is provided so it can be called when the request is 

        //completed. The Current SynchronizationContext is provided as 

        state so it can be handled by the result.

        request.BeginGetResponse(OnRequestCompleted, 

                                 SynchronizationContext.Current);

    }

    //when the request is completed this method is called

    private void OnRequestCompleted(IAsyncResult ar)

    {

        //the response is extracted from the result and read thru a stream.

        var webResponse = (HttpWebResponse)request.EndGetResponse(ar);

        var response = new StreamReader(webResponse.GetResponseStream());

        //Because a string of Json is returned by the service, this string is 

        //parsed into a JsonObject.

        var json = JsonObject.Parse(response.ReadToEnd());

        //the ExtractResults method (defined below) is used to create 

        //an enumeration of the results

        IEnumerable<BingResult> ress = ExtractRestults(json);

        // this method (defined below) is used to fire a custom event on the UI thread

        // the state is provided as Synchronization context along with the json results

        InvokeSearchBingCompletedEvent(ar.AsyncState as SynchronizationContext, ress);

    }

    private void InvokeSearchBingCompletedEvent(SynchronizationContext context, 

                                                IEnumerable<BingResult> ress)

    {

        if (context != null) // just in case the context has become null somehow

            // call an anonymous method asynchronous on the context that was used to start 

            //the search

            context.Post((e) => 

                     {

                         if (SearchBingCompleted != null) 

                             //raise the event

                             SearchBingCompleted(this, new SearchBingCompletedArgs() 

                                                   {

                                                       SearchResults = ress.ToList()

                                                   }

                                 );

                     }, null);

    }

    // Extract search result from Json returned by Bing API  

    private static IEnumerable<BingResult> ExtractRestults(JsonValue json)

    {

        var results = json["SearchResponse"]["Web"]["Results"] as JsonArray;

        return from res in results

               select new BingResult()

                          {

                              Title = res["Title"],

                              Url = res["Url"]

                          };

    }

    // the definition of the event handler

    public event EventHandler<SearchBingCompletedArgs> SearchBingCompleted;

}