2.0: Exposing and using data in the Web services domain

This article is based on the pre-release version of ASP.net 3.5 and the Microsoft AJAX library. All the information in this article may be changed.

This article describes the following:

The meaning of data services

Exposing and using data

Using the Entity Data model to describe data

Data security

This article uses the following techniques:

Ado.net Data Services, LINQ, and Entity data models

Think back to the rich Internet application (RIA) you built last time. How did you get your data? How do you differentiate between this data and the presentation and user interface (UI) information that is sent to the browser? What if there is a simpler way to do this?

Separating presentations and data is not a new idea, but it is becoming more popular as RIA technologies, such as AJAX and silverlight™, become more prevalent. These technologies are built on the idea of separating presentations and data to develop more interactive and responsive applications.

For example, a Silverlight-based RIA application can precompile code to drive a presentation and deploy that code to the client through a WEB server. Then, when you reach the Web browser, the code will callback to the Web server to retrieve the data to be displayed in the user interface. Such techniques typically do not require the server-side rendering process to be selected, as this mixes data with presentation code.

In addition to separating presentations and data to make the Web experience richer and more interactive, the web also has a tendency to expose and use independent data that is independent of any user interface. The wide application of data-driven applications, such as "Resource aggregation", shows that the promotion of meaningful and easy-to-use data creates new application scenarios.

Based on the observation of these trends, the Ado.net Data Services Framework was originally designed to help developers who want to expose and use data through services in their RIA applications. In exploring this field, there are two main ideas: the idea of using existing methods to build common client libraries and tools for data-centric services is difficult; creating and maintaining these services requires a large number of developers. In this article, we will focus on what data services are and how many of the main features are.

In general, the goal of the Ado.net Data Services framework is to create a simple framework based on representational state transfer (REST) for exposing and using data-centric services. Such services use a unified interface to expose data for use by all WEB clients across the enterprise Intranet or the Internet. The framework consists of a server library and a set of client libraries that are used to expose data as a service security, which is built for a range of Microsoft applications and Technologies (Microsoft®.net Framework and Silverlight, etc.) that can be used with services. Figure 1 shows the architecture.

Figure 1 Ado.net Data Service Framework Architecture