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WCF RIA Service

In this tutorial I will explain about RIA(Rich Internet Application) WCF service in a silverlight application.

Software Requirement

Before you start reading this tutorial you should make sure that

Visual studio 2010 is installed on your machine.
WCF RIA Services SP2 for Silverlight 4 and 5 are installed on your machine.
WCF RIA Services Toolkit is installed on your machine.

Prerequisite Knowledge

Before you go ahead, it is required that you should know

How ASP.NET application works?
What is XAML file?
How to bind a silverlight control like combobox from a datasource?
What is ADO.NET entity model?
How to query to data source using LINQ?
What is IEnumerable and IQueryable interfaces?

ASP.NET Application Vs Silverlight Application

Picture showing how the application is layered in traditional web application

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In the traditional web applications data access layer, business layer and presentation layer are placed on server. When the request comes from the browser, the request is processed and output in the form of HTML is rendered.

Picture showing how the application is layered in silverlight application

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But in case of silverlight application the presentation layer resides on the client and business layer resides on the server. RIA WCF service is a resource that resides between the presentation layer and business layer and from which interaction between the two layers is possible.

Creation Of A New Project

First of all create a new silverlight application by selecting Silverlight Application from visual studio installed templates.

Picture showing creating a new project of type silverlight application

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When you click ok a popup will open which asks you whether you want to create a web application as well.

Picture showing selecting the version of silverlight and enabling WCF RIA service

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The checkbox Enable WCF RIA Service when checked ensures that application created should support RIA WCF service.

See the folder structure for the project in the figure below.

Picture showing the project structure in the solution explorer of the visual studio

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Add Data Tables

Once the project is created the next step is to add a datasource in the project. For this tutorial I am creating two tables

Picture showing the data in category and books table

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First table contains the category of books and the second table contains the name of the books category wise.

Add ADO.NET Entity Data Model

Now add an ADO.NET entity data model in the web application. For that right click on the web application and click Add New Item. Once you click on it, a pop window comes as shown in figure below.

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Select ADO.NET Entity Data Model and click Add. A new window appears from which you can choose whether to generate the model from the database or create an empty model.

Picture showing the window to select model contents

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Select Generate from database option and click next

Picture showing a window to select the data source

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On click of next button,a windows comes to select the datasource(See the above figure). If you already have the database mapped then this window will show the details of the database else you have to create a new connection by clicking on New Connection… button.

Picture showing the database objects of the selected data source

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Once you have selected the datasource click on next. The next screen shows you the database objects the database contains.

Select Tables checkbox and click Finish

Once you click finish a new datamodel is added in the web application.

Picture showing the new data model added in the web application

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Adding A Domain Service Class

The next step is to add file of type domain service. Again right click on the web application and click Add New Item.

Picture showing adding the domain service class in the project

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Select Domain Service Class and click Add. A new popup window appears

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The checkbox Enable client access ensures that this service should be accessible to client. Second point to notice here is Entities section. Here the list of tables present in database is displayed.

If there are 5 tables in the database and you have selected only 2 tables (without selecting Enable editing checkbox) then it means 2 methods are generated in code, one for selecting Book and other is for selecting categoryTable. Enable editing checkbox ensures that code for insert, update and delete should also generate(see the image below. This code is generated when user clicks ok button after selecting tables.).

Click Ok. Domain Service file is added in the website

Domain Service Code

Picture showing the autogenerated code of the domain service class

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The figure above is the code generated in the domain service class. In the CategoryTable entity I had enabled edit so there are three extra functions generated (InsertCategoryTable, UpdateCategoryTable and DeleteCategoryTable). There are two methods for selecting records from each table(GetBooks and GetCategoryTables).

Now add some code in the client part i.e. silverlight application. In the file MainPage.xaml add following code

Adding Code In Xaml File

Picture showing adding the code in the MainPage.xaml file

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In the code we have a combobox and a button. Our job is to bind the combobox with data of CategoryTable entity on button click.

Now add the following code in code behind

Calling RIA WCF Service Through Code Behind

Picture showing how to call RIA WCF service through code behind

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First of all add the namespace RIAQCFDemo.Web. Then call method BindControl() on button click. In the method BindControl() first of all I am creating an instance of MyDomainContext class which is generated when domain service class was created.

In the second line I am calling the method GetCategoryTablesQuery() method. In the third line I am calling Load method which calls the database and loads the result.

Once the data is loaded loadOp_Completed method is called and gets the result in a variable of type List using LINQ. Finally bind the list to the combo box.

When you run the program the following output will come.

Output

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Conclusion

Silverlight is a client side technology. To connect to the server the technology needs a medium and RIA wcf service is that medium.

WCF Vs WCF RIA Service

WCF RIA service runs on top of WCF framework. WCF RIA service simplifies the development of n-tier solution for Rich Internet Applications like Silverlight.

Posted By -	Karan Gupta

Posted On -	Thursday, January 19, 2012

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