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Remember that thanks to inheritance, the strongly typed DataSet really is a DataSet. This means you can Tip seamlessly cast the NorthwindDataSet class to the DataSet class and use ordinary string-based field and table lookup. However, the reverse is not true you can t cast an ordinary DataSet to the NorthwindDataSet type.

Allowed Data Types Storage Location Lifetime All serializable .NET data types. Nonserializable types are supported if you create a custom profile. A back-end database. Permanent.

Depending on the scenario, you might be able to respond to data source control events, but they aren t always fired at the point you need to perform your logic Essentially, data binding tasks take place in this order: 1 The page object is created (based on the aspx file) 2 The page life cycle begins, and the PageInit and PageLoad events fire 3 All other control events fire 4 The data source controls perform any updates If a row is being updated, the Updating and Updated events fire If a row is being inserted, the Inserting and Inserted events fire If a row is being deleted, the Deleting and Deleted events fire 5 The PagePreRender event fires 6 The data source controls perform any queries and insert the retrieved data in the linked controls The Selecting and Selected events fire at this point 7.

Summary

Server memory. Depends on the expiration policy you set but may possibly be released early if server memory becomes scarce. The same as application state (global to all users and all pages). Very secure, because data is never transmitted to the client. Storing a large amount of information may force out other, more useful cached information. However, ASP .NET has the ability to remove items early to ensure optimum performance. Storing data retrieved from a database.

The page is rendered and disposed In the rest of this chapter, you ll look in detail at the SqlDataSource and the ObjectDataSource and see how you can use both to enable a variety of data binding scenarios with the rich GridView control..

In this chapter, you learned how to create basic database components and took an in-depth look at the DataSet and DataView. In the next chapter, you ll continue working with the same database component and the DataSet albeit through a new layer. You ll learn how the data source controls wrap the ADO.NET world with a higher-level abstraction and let you build rich data-bound pages with minimal code. If you want to learn about all the features of the DataSet, including those that are tailored to distributed and rich client applications, you may want to consult Programming Microsoft ADO.NET 2.0: Core Reference (Microsoft Press, 2005) or Pro ADO.NET 2.0 (Apress, 2005).

The whole ASP.NET application. May also be accessed by other applications. Fairly secure, because although data is never transmitted, it is stored in a database that could be compromised. Large amounts of data can be stored easily, but there may be a nontrivial overhead in retrieving and writing the data for each request. Store customer account information.

Even if you plan to use the ObjectDataSource for binding your pages, you should begin by reading The SqlDataSource section, which will explain many of the basics about data source controls, including parameters, key fields, and two-way data binding.