Applied XML Programming for Microsoft .NET.pdf - Csbdu.in

{// Propertiesprotected SalesDataProvider m_dataManager;// Constructorpublic ServiceSalesProvider(){m_dataManager = new SalesDataProvider();}// GetSalesReportpublic DataSet GetSalesReport(int theYear){DataSet ds = new DataSet();ds.Tables.Add(m_dataManager.GetSalesReport(theYear));return ds;}}// GetSalesReportBarChartpublic string GetSalesReportBarChart(int theYear){return m_dataManager.GetSalesReportBarChart(theYear);}The SalesDataProvider protected member is initialized only once, when theServiceSalesProvider class instance is constructed. After that, any call to the variousmethods is resolved using the same instance of the helper class.The ServiceSalesProvider class has two public methods with the same names as themethods in SalesDataProvider. The implementation of these methods is straightforwardand fairly self-explanatory. The only aspect worth noting is that the remotableGetSalesReport method adds the DataTable object returned by the correspondingmethod on the SalesDataProvider class to a newly created DataSet object. TheDataSet object is then returned to the caller.NoteWhen writing remotable classes, be sure that all the methods useand return serializable classes. No extra steps are required if youdecide to write your own, user-defined classes as long as theyinclude SerializableAttribute or implement the ISerializable interface.Publishing the Remote Service ComponentTo be usable in a distributed environment, a remotable class must be configured andexposed so that interested callers can reach it. A remotable object needs a runninghost application to handle any incoming calls. In addition, the object must specify whatprotocol, port, and name a potential client must use to issue its calls. All requirementsthat callers must fulfill are stored in the remote object's configuration file.438