ObjectDataSource Control
The large web application are normally layered as,

·          Presentation Layer

·          Business Objects

·          DAL

Our previous examples in Part 1 does everything in ASP.Net Page itself and also it has some disadvantages like if the underlying the table schema changes then we have to re configure the Datasource control.
For doing the above with ObjectDataSource control we have to design an entity (Business Object) and DAL to access the DB. In our example it is Employee and EmployeeDAL.
Employee.cs

public class Employee
{
#region Private Members
private int empid;
private string fname;
private string lname;
private string gender;
private DateTime dob;
#endregion
#region Public Properties
public int EmpID
{
get
{
return empid;
}
set
{
empid = value;
}
}
public string FirstName
{
get
{
return fname;
}
set
{
fname = value;
}
}
public string LastName
{
get
{
return lname;
}
set
{
lname = value;
}
}
public string Gender
{
get
{
return gender;
}
set
{
gender = value;
}
}
public DateTime DOB
{
get
{
return dob;
}
set
{
dob = value;
}
}
#endregion
}

EmployeeDAL.cs
public static void UpdateEmployee(int empid, string firstname, string lastname, string gender, DateTime dob)
{
//For Update
}
public static List Getemployee(string sortexp)
{
//For Sorting
}
public static List Getemployee(int maximumRows,int startRowIndex,string sortexp)
{
//For Paging
}
public static void DeleteEmployees(int Empid)
{
//For Deleting
}

Steps for using ObjectDataSource Controls
1) Drag an ObjectDataSource and Gridview Control from the data tab in visual studio.
2) Click Configure Datasource and set the DAL as shown in figure. Click Next.

3) Select the select, update and delete methods as shown in figure and Click Finish as shown in Figure.

4) Set the DatasourceID of the Gridview to Datasource ID of the Object Datasource.Set Paging,Editing,sorting and Deleting.
5) Run the application.

Things to Remember
Update
Make sure that the column name in Gridview and the arguments of the Update Method are same. The signature for the Update method depends on the ObjectDataSource's ConflictDetection property. If you are using the default behavior OverwriteChange then the Update method needs to accept the original primary key field(s) along with parameters for the non-primary key updated values. If, on the other hand, CompareAllValues is used, the Update method must accept both the updated and original non-primary key field values along with the original primary key field(s).

Sorting and Paging
For a pageable GridView from an ObjectDataSource the underlying DAL class's SELECT method must accept the following inputs: the first one specifying the maximum number of records to return as int and the second specifying the starting record index as int and the third one will be SortExpression as string. The following parameters should be set in ObjectDatasource for Sorting and Paging to work.

EnablePaging, set this to true.
MaximumRowsParameterName, this property provides the name of the first integer parameter to the method that pages the results. It defaults to maximumRows. If you use a different parameter name in your methods, you'll need to specify that parameter name in this property.
StartRowIndexParameterName is similar to MaximumRowsParameterName, in that this property value specifies the second integer parameter name for paging. It defaults to startRowIndex, so we need to set this property explicitly if we use a different parameter name in your code.
SelectCountMethod  is the name of the method that returns the total number of records to be paged through.
SortParameterName is the name of the string input parameter specifying how to sort the data. In my example I used sortexp.
Deleting
Specify the DataKeyNames to Primary key filed in GridView Property.

XmlDataSource
For understanding the XmlDataSource we need an XML data file.

Steps for using XmlDataSource controls
1) Drag a GridView and XmlDatasource controls from the toolbox.
2) Configure the XmlDataSource to get the data from an xml source as shown below.

The above window shows 3 textbox but specifying data file alone will do.
The above window takes,
1. The path to the XML file, which is required.
2. The path to an XSD file that defines the schema for the XML file. You do not need to provide a schema, as the XmlDataSource does not use schema information at all. However, a data Web control might require type-specific information, which the schema file provides.
3. An optional path to an XSL transform file. If the XML in the file does not conform to a structure you want, you can specify a translation through this XSL transform file setting.
4. An optional XPath expression, useful for filtering the data returned by the XmlDataSource. By default, the entire contents of the XML file will be loaded by the XmlDataSource. By specifying an XPath expression, however, you can limit those elements retrieved.