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Benefits of ADO.NET

.NET Framework 3.5

ADO.NET offers several advantages over previous versions of ADO and over other data access components. These benefits fall into the following categories:

ADO.NET applications can take advantage of the flexibility and broad acceptance of XML. Because XML is the format for transmitting datasets across the network, any component that can read the XML format can process data. In fact, the receiving component need not be an ADO.NET component at all: The transmitting component can simply transmit the dataset to its destination without regard to how the receiving component is implemented. The destination component might be a Visual Studio application or any other application implemented with any tool whatsoever. The only requirement is that the receiving component be able to read XML. As an industry standard, XML was designed with exactly this kind of interoperability in mind.

In the life of a deployed system, modest changes are possible, but substantial, architectural changes are rarely attempted because they are so difficult. That is unfortunate, because in a natural course of events, such substantial changes can become necessary. For example, as a deployed application becomes popular with users, the increased performance load might require architectural changes. As the performance load on a deployed application server grows, system resources can become scarce and response time or throughput can suffer. Faced with this problem, software architects can choose to divide the server's business-logic processing and user-interface processing onto separate tiers on separate machines. In effect, the application server tier is replaced with two tiers, alleviating the shortage of system resources.

The problem is not designing a three-tiered application. Rather, it is increasing the number of tiers after an application is deployed. If the original application is implemented in ADO.NET using datasets, this transformation is made easier. Remember, when you replace a single tier with two tiers, you arrange for those two tiers to trade information. Because the tiers can transmit data through XML-formatted datasets, the communication is relatively easy.

ADO.NET data components in Visual Studio encapsulate data access functionality in various ways that help you program more quickly and with fewer mistakes. For example, data commands abstract the task of building and executing SQL statements or stored procedures.

Similarly, ADO.NET data classes generated by the designer tools result in typed datasets. This in turn allows you to access data through typed programming. For example, consider the following line of code that accesses a data member in an untyped dataset:

if (totalCost > (double)dataSet1.Tables["Customers"].Rows[n]["AvailableCredit"])

The equivalent line to access a data member in a typed dataset looks like the following:

if (totalCost > dataSet2.Customers[n].AvailableCredit)

The code for the typed dataset is easier to read. It is also easier to write, because statement completion is provided. For example, "AvailableCredit" is among the list of choices for completing the following statement:

If totalCost > dataSet2.Customers(n).

Finally, the code for the typed dataset is safer, because it provides for the compile-time checking of types. For example, suppose that AvailableCredit is expressed as a currency value. If the programmer erroneously assigns a string value to AvailableCredit, the environment would report the error to the programmer during compile time. When working with untyped datasets, the programmer would not learn of the error until run time.

For more information about typed and untyped datasets, see Datasets in Visual Studio Overview.

For disconnected applications, ADO.NET datasets offer performance advantages over ADO disconnected recordsets. When using COM marshalling to transmit a disconnected recordset among tiers, a significant processing cost can result from converting the values in the recordset to data types recognized by COM. In ADO.NET, such data-type conversion is not necessary.

Because the Web can vastly increase the demands on your data, scalability has become critical. Internet applications have a limitless supply of potential users. Although an application might serve a dozen users well, it might not serve hundreds —or hundreds of thousands — equally well. An application that consumes resources such as database locks and database connections will not serve high numbers of users well, because the user demand for those limited resources will eventually exceed their supply.

ADO.NET accommodates scalability by encouraging programmers to conserve limited resources. Because any ADO.NET application employs disconnected access to data, it does not retain database locks or active database connections for long durations.