Monday, April 27, 2009

Creating the client application

In most regards, creating a multi-tiered client application is similar to creating a traditional two-tiered client. The major differences are that a multi-tiered client uses

A connection component to establish a conduit to the application server.
One or more TClientDataSet components to link to a data provider on the application server. Data-aware controls on the client are connected through data source components to these client datasets instead of TTable, TQuery, TStoredProc or TADODataSet components.

To create a multi-tiered client application, start a new project and follow these steps:
1.Add a new data module to the project.

2.Place a connection component on the data module. The type of connection component you add depends on the communication protocol you want to use.

3.Set properties on your connection component to specify the application server with which it should establish a connection. To learn more about setting up the connection component.

4.Set the other connection component properties as needed for your application. For example, you might set the ObjectBroker property to allow the connection component to choose dynamically from several servers. For more information about using the connection components.

5.Place as many TClientDataSet components as needed on the data module, and set the RemoteServer property for each component to the name of the connection component you placed in Step 2.

6.Set the ProviderName property for each TClientDataSet component. If your connection component is connected to the application server at design time, you can choose available application server providers from the ProviderName property’s drop-down list.

7.Create the client application in much the same way you would create any other database application. You will probably want to use some of the special features of client datasets that support their interaction with the provider components on the application server.

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