Written by: Michael Washington
6/3/2012 7:14 PM 

The following is an excerpt from the book: OData And Visual Studio LightSwitch Using ASP.NET / Windows Phone / jQuery / datajs / Knockout available at: http://lightswitchhelpwebsite.com/Market/Books/ODataAndVisualStudioLightSwitch.aspx.

Chapter 1: What Is This Book About?

This book is about Microsoft Visual Studio LightSwitch and OData. The purpose of this book is to demonstrate its use, and explain its importance.

What Is Visual Studio LightSwitch?

Visual Studio LightSwitch is a development tool that provides the easiest and fastest way to create ‘forms over data, line of business applications’. It allows you to build applications for the desktop and the cloud. It does this by allowing you to quickly and easily define and connect to your data, program your security and business rules, and expose this via OData to practically any ‘client’ such as mobile devices and web pages.

What Is OData?

OData is a protocol used to expose and consume data over the web. It uses a common REST-like (representational state transfer) interface to communicate, rather than the usual pre-defined application specific interfaces used by traditional web services. OData is a project created by Microsoft. The home page for the project is at: http://www.odata.org.

As described in the article: LightSwitch Architecture: OData (John Rivard) (http://blogs.msdn.com/b/lightswitch/archive/2012/03/22/lightswitch-architecture-odata.aspx), OData allows CRUD (Create, Read, Update, Delete) operations using the following HTTP (Hypertext Transfer Protocol) verbs:

• Create: POST
• Read: GET
• Update: PUT
• Delete: DELETE

This allows you to have full data interaction when you use OData. In addition, OData provides a mechanism to query the data. For example, in subsequent chapters we will demonstrate how a mobile application is able to query for orders for a specific customer. This is done without the need to define a “get customer orders” web service. We simply use the standard OData protocol.

OData is Communication with Clients and Servers Outside of Your LightSwitch Application

Communication between your LightSwitch application, and clients that need to communicate with it, is very important. For example, allowing a user to place orders in your LightSwitch application using a mobile phone or a tablet is an important component to creating productive applications for your end users.

OData Allows You to Centralize Your Business Rules and Security

Security is an important aspect of your application. Using LightSwitch, you are able to easily configure security.

The following code restricts a non administrator from accessing any order that is not their own:

This code needs to be implemented only once to protect the data and to enforce the business rule, no matter what client is being used.

This allows you to centralize your business rules and security and have them enforced consistently no matter what client (web page, mobile phone, IPad) is accessing it.

You will not need to duplicate the business rules and security in each client that consumes your application. Each client will be simpler to create, and easier to maintain.

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