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

Figure 10-10: The user interface of the application when the batch update fails on a row.Notice the custom error message on the row in error. This message is obtained usingthe following code:// Select all the rows in error after the batch updateforeach(DataRow row inm_dataSet.Tables["Employees"].GetErrors()){string msg = row.RowState.ToString() + "row. Failed.";row.RowError = msg;}Updating conflicts and reconciling tables after a batch update procedure can beexpensive. Sometimes, it might be even more costly than working connected. Choosingthe right application perspective is a delicate task with quite a simple guideline: go fordisconnection if you have a low degree of data contention and your tables aren'tupdated frequently with highly volatile data.ConclusionIf you've recently programmed data-driven applications, disconnected programming isnothing new for you. Disconnected scenarios are key in the era of the Internet, as theylet you gain in scalability and mobility, bringing simplification to the software and to theuser. For disconnected applications, effective local copies of the data are more thanvital—they're absolutely mandatory.For .NET Framework applications, the DataSet object is the ideal candidate to take theposition of the client-side data container in disconnected, intermittent applications. Inthis chapter and in Chapter 9, we analyzed various options for serializing the contentsof a DataSet object to output streams. In this chapter in particular, we analyzed astateful way to persist the DataSet contents.In general, there are two different angles from which you should look at the DataSetobject's serialization. One is the physical layout of the data when stored to disk; theother is the statefulness of the format. Normally, a DataSet object serializes itself usinga couple of XML blocks—schema and data. This data can then be saved as is to a textor SOAP output stream or saved to a more compact binary stream. In this case,385