DataSets vs. Collections

DataSets vs. Collections by Dino Esposito对比分析了DataSet, Typed DataSet和Custom Entities and Collections（定制业务实体和集合）作为multi-tier之间的数据传递，并阐述各自的适用情况（When to Use Which）。

 
When to Use Which

Both DataSets and custom classes don't limit what you can do in any way, and both can be used to accomplish the same aims. That said, DataSets are fantastic tools for prototyping applications and represent excellent solutions for building systems in a kind of emergency—a limited budget, an approaching deadline, or a short application lifetime. For relatively simple applications, custom entities add a perhaps unnecessary level of complexity. In this case, I suggest that you seriously consider using DataSets.

In the economy of a large, durable, complex enterprise system that takes several months to complete, the cost of architecting and implementing a bunch of collections classes is relatively minimal and is incurred only once. The advantages in terms of performance, expressivity, readability, and ease of maintenance largely repay the investment. You are not bound to a tabular rendering of data. Business rules and custom business entities can't always be adapted to look like a collection of tables. In general, you should avoid adapting data to the data container—quite the reverse, I'd say. Finally, using custom classes makes for easier unit testing because classes and logic are more strictly related than with DataSets. In Figure 3, you find a synoptic table with DataSets, typed DataSets, and custom entities compared by several factors.

In any case, bear in mind that your decision should be based on full awareness of the benefits, implications, and repercussions. If you go for custom classes, take a look at some commonly used enterprise design patterns. Figure 4 details a few of them.

Wrap Up

The DataSet versus custom collection disagreement is an old one that for various reasons has never escalated into an outright war. However, the advent of the .NET Framework 2.0 and generics enables developers to generate and manage collections much more quickly and effectively. For example, implementing IBindingList—which is required for data binding—is as easy as adding a couple of overrides to a generic class. This could push the use of custom entities by making it affordable for more developers and in more scenarios. For this reason, it's more important than ever to learn the underpinnings of DataSets and collections so you can make your choice consciously and wisely. For more information on these topics, take a look at the following blogs: Scott Hanselman's at Returning DataSets from WebServices is the Spawn of Satan and Represents All That Is Truly Evil in the World, Jelle Druyts' at DataSets Are Not Evil, Andrew Conrad's at Nix the DataSet??????, and ObjectSharp at DataSet FAQ.

The URL of the Article:

http://msdn.microsoft.com/msdnmag/issues/05/08/CuttingEdge/default.aspx by Dino Esposito.