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If you find that your application domain is being restarted frequently and contributing to prematurely lost sessions, you can try to counter the effect by changing some of the process model settings (see 18), or you can change to one of the more robust session state providers Before you use either the out-of-process or the SQL Server state service, keep in mind that more considerations will apply: When using the StateServer or SqlServer mode, the objects you store in session state must be serializable Otherwise, ASPNET will not be able to transmit the object to the state service or store it in the database If you re hosting ASPNET on a web farm, you ll also need to take some extra configuration steps to make sure all the web servers are in sync.

If you have an existing web application created with Visual Studio .NET 2002 or 2003, you can open the project or solution file using the File Open Project command. When you do, Visual Studio begins the Conversion Wizard. The Conversion Wizard is exceedingly simple. It prompts you to choose whether to create a backup and, if so, where it should be placed (see Figure 2-3). If this is your only copy of the application, a backup is a good idea in case some aspects of your application can t be converted successfully. Otherwise, you can skip this option.

The GridView sorting features allow the user to reorder the results in the GridView by clicking a column header. It s convenient and easy to implement. To enable sorting, you must set the GridView. AllowSorting property to True. Next, you need to define a SortExpression for each column that can be sorted. In theory, a sort expression can use any syntax that s understood by the data source control. In practice, a sort expression almost always takes the form used in the ORDER BY clause of a SQL query. That means the sort expression can include a single field or a list of comma-separated fields, optionally with the word ASC or DESC added after the column name to sort in ascending or descending order. Here s how you could define the FirstName column so it sorts by alphabetically ordering rows by first name: <asp:BoundField DataField="FirstName" HeaderText="First Name" SortExpression="FirstName"/> Note that if you don t want a column to be sort-enabled, you simply don t set its SortExpression property.

Otherwise, one might encode information in session state differently than another, which will cause a problem if the user is routed from one server to another during a session The solution is to modify the <machineKey> section of the machineconfig file so it s consistent across all servers For more information, refer to 5 If you aren t using the in-process state provider, the SessionStateModuleEnd event won t be fired, and any event handlers for this event in the globalasax file or an HTTP module will be ignored..

Figure 2-3. Importing a Visual Studio .NET 2003 project When you click Finish, Visual Studio performs an in-place conversion. The conversion tool is fairly aggressive, and it attempts to convert every web page to use Visual Studio s new code-behind model. Any errors and warnings are added to a conversion log, which you can display when the conversion is complete. In a typical website, the conversion operation runs without any errors but generates a long list of warnings. These inform you when Visual Studio removes precompiled files, changes pages to use automatic event wire-up, and modifies the accessibility of event handlers (switching them from private to protected). All of these changes are minor modifications designed to apply the new code model, which is described in the section The Code Model later in this chapter. Figure 2-4 shows a sample log.

If you use autogenerated columns, each bound column has its SortExpression property set to match the DataField property.