WCF REST and Silverlight Synchronous calls within same domain

In my previous blog Silverlight and WCF REST near synchronous calling we saw how to achieve near synchronous behavior in the cross domain scenario. But if you have the advantage of hosting the WCF REST in the same domain of Silverlight; it is possible to achieve synchronous behavior using Wilco's HTTP requests for Silverlight

Below is the sample code which I used;
var result = Request.To("/services1.svc/DoWork")
.WithHeader("Content-Type","application/xml")
.Send().ReadAllText();

ASP.NET Validators inside AJAX UpdatePanels

Got a requirement to use ASP.NET Validators inside AJAX UpdatePanels? Don't worry, here is the solution. Just follow the steps provided in the link below;
http://blogs.msdn.com/b/mattgi/archive/2007/01/23/asp-net-ajax-validators.aspx

Silverlight and WCF REST, near synchronous calling

It may be very annoying since Silverlight doesn't provide synchronous calls with WCF. Loads and loads of debate happened around this but no concrete solution yet out in the market. I tried to solve this problem to an extend (not exactly synchronous) using Microsoft Rx (Reactive Extensions) framework and Wilco Bauwer's Http Request in Silverlight approach. See below how I did;


Microsoft Rx Extensions


1) Download the Microsoft Reactive Extensions framework
2) Add the System.Reactive.dll assembly reference to your Silverlight app
3) Add the following property and private variables;


private string _result;
protected bool _pageRefreshed;
public string Result1
{
get
{
return _result;
}
set
{
_result = value;
_pageRefreshed = true;
MainPage_Loaded(null, null);
}
}


Here what I am trying to do is that, instead of having the separate delegate function to handle the callback, I am pushing the callback to Silverlight Page_Loaded event. This is very similar to the way we deal with Postbacks in Page_Load in ASP.NET


4) Use this code to invoke your WCF REST service


WebClient client1 = new WebClient();
Uri url = new Uri(https://www.WCFRESTService.Demo/BLServiceImplementation.svc/TraceError);
string input = "<LoggingServices_TraceError xmlns='http://tempuri.org/'><message>Hello!! I am from Silverlight!!!</message></LoggingServices_TraceError>";


var o = Observable.FromEventPattern(client1, "UploadStringCompleted").Select(newstring => newstring.EventArgs.Result);

o.Subscribe(s => Result1 = s);


client1.Headers["Content-Type"] = "application/xml";
client1.UploadStringAsync(url, input);


This is how it works, the result from asynchronous WCF REST call will be assigned to the Result1 property. In the Set section, after assigning to the local variable; I am also firing the Page_Loaded event of silverlight.
And in the Page_Loaded event, I am handling the result like shown below;


void MainPage_Loaded(object sender, RoutedEventArgs e)

{
if (_pageRefreshed == true)
{
_pageRefreshed = false;
result.Text = _result;
return;
}
}

Wilco Bauwer's Http Request in Silverlight approach

1) Download the code from Wilco HTTP Request and Silverlight
2) Before actually using this in you application, you need to get the code build.
3) Also, you need to make some modifications to be able to use XML and JSON WCF REST calls. Locate the Request.cs file and modify the SetRequestProperties as shown below;

private void SetRequestProperties(HttpWebRequest request) {

request.Method = _method;
foreach (var entry in _headers) {
if (entry.Key.ToLower() == "content-type")
{
request.ContentType = entry.Value;
}
else
request.Headers[entry.Key] = entry.Value;
}
}
4) Follow Step 3 in the above approach
5) Use the code below to call the WCF REST service;
Request.To(https://www.WCFREST.Demo/BLServiceImplementation.svc/TraceError)

.WithHeader("Content-Type", "application/xml")
.WithMethod("POST")
.WithBody("Hello!! I am from Silverlight!!!")
.SendAsync(response => Result1 = response.ReadAllText());

The approach is same as above except that Wilco provides Fluent Interface which is the user friendly LINQ.
The Page_Load code also same except for one small modification as below;

Dispatcher.BeginInvoke(()=> {

result.Text = _result;
});

You will make to wrap any assignment to UI controls with Dispatcher.BeginInvoke otherwise you will get cross thread access issue.

Happy coding!!! Let me know if you face any issues.

ScreenUpdating property and Excel/Word/Outlook Add-In

Recently while developing an Excel Add-In we faced a peculiar problem of Excel worksheet hanging after completing the processing. No problem in functionality, no memory leaks, no exceptions and nothing... We were breaking our heads where else it could fail...

After a couple of trials, we figured out that Workbook.ActiveWorksheet.ScreenUpdating was set to FALSE and was not turned back to TRUE. We usually set ScreenUpdating to FALSE to speed up the macro processing, but if we forget to turn back to TRUE; thats it; you will think Excel is hanging or something happened.. So please watch out while using ScreenUpdating in your code :)

Silverlight Integration in DNN

Here are the simple steps to integrate Silverlight in DotNetNuke.
1) Publish the silverlight application

2) Host the published silverlight application in IIS

3) Goto the DNN website. Create a web page for hosting the silverlight application

4) 4) Add the “HTML” module to the newly created page. And then, go to the HTML view in the Rich Text Editor. Place the <IFRAME> tag with the src to the silverlight HTML page hosted in IIS in the above steps

5) Voila!!! Now you can see that silverlight functionality working in the DNN site