Serialization: SOAP

1. Start a new Windows Application named WattsALoan3
2. In the Solution Explorer, right-click Form1.cs and click Rename
3. Type LoanPreparation.cs and press Enter
4. Design the form as followed:
    

   Control Name Text Additional Properties GroupBox   Loan Identification   Label   Prepared &By:   TextBox txtEmployeeName     Label   Customer First Name:   TextBox txtCustomerFirstName     Label   Last Name:   TextBox txtCustomerLastName     GroupBox   Loan Preparation   Label   Principal:   TextBox txtPrincipal 0.00 TextAlign: Right Label   Interest Rate:   TextBox txtInterestRate 8.25 TextAlign: Right Label   %   Label   Periods:   TextBox txtPeriods 1 TextAlign: Text ComboBox cbxPeriods Months Items: Years Months Days GroupBox   Results   Button btnCalculate Calculate   Label   Interest Earned:   TextBox txtInterestEarned 0.00 TextAlign: Right ReadOnly: True Label   Amount Earned:   TextBox txtFutureValue 0.00 TextAlign: Right ReadOnly: True GroupBox   File Processing   Label   Loan ID:   TextBox txtSave     Button &Save btnSave   Label   Loan ID:   TextBox txtOpen     Button &Open btnOpen   Button btnClose Close

5. On the form, click the Last Name text box
6. In the Properties window, click the Events button and double-click Leave
7. Implement the event as follows:
   

   private void txtCustomerLastName_Leave(object sender, EventArgs e)
   {
       var Initials = "00";
       var FirstName = txtCustomerFirstName.Text;
       var LastName = txtCustomerLastName.Text;
   
       if (LastName.Length == 0)
       {
           MessageBox.Show("You must enter a last name");
           txtCustomerLastName.Focus();
           return;
       }
   
       if (FirstName.Length == 0)
           Initials = LastName.Substring(0, 1) + "1";
       else
           Initials = FirstName.Substring(0, 1) + LastName.Substring(0, 1);
   
       txtSave.Text = Initials;
   }

8. Return to the form
9. On the form, double-click the Calculate button and implement its Click event as follows:
   

   private void btnCalculate_Click_1(object sender, EventArgs e)
   {
       var Principal = 0.00;
       var InterestRate = 0.00;
       var InterestEarned = 0.00;
       var FutureValue = 0.00;
       var Periods = 0.00;
               
       // Retrieve the value of the principal
       try
       {
           Principal = double.Parse(txtPrincipal.Text);
       }
       catch (FormatException)
       {
           MessageBox.Show("The value you entered for the principal " +
                           "is not valid.\nPlease try again");
       }
   
       // Retrieve the interest rate
       try
       {
           InterestRate = double.Parse(txtInterestRate.Text) / 100;
       }
       catch (FormatException)
       {
           MessageBox.Show("The value you entered for the interest " +
                           "rate is not valid\nPlease try again");
       }
   
       // Get the number of periods
       try
       {
                   if (cbxPeriods.SelectedIndex == 0) // Years
                       Periods = double.Parse(txtPeriods.Text);
                   else if (cbxPeriods.SelectedIndex == 1) // Months
                       Periods = double.Parse(txtPeriods.Text) / 12;
                   else // if (cbxPeriods.SelectedIndex == 2)  Days
                       Periods = double.Parse(txtPeriods.Text) / 360;
       }
       catch (FormatException)
       {
           MessageBox.Show("The value you entered for the number " +
                           "of periods is not valid\nPlease try again");
       }
   
       var InterestRatePeriods = InterestRate * Periods;
       var InterestPlus1 = InterestRatePeriods + 1;
       FutureValue = Principal * InterestPlus1;
       InterestEarned = FutureValue - Principal;
   
       txtInterestEarned.Text = InterestEarned.ToString("F");
       txtFutureValue.Text = FutureValue.ToString("F");
   }

10. Execute the application to make sure it is fine
11. After using it, close the form and return to your programming environment

To serialize an object using SOAP, you follow the same steps we reviewed for the binary serialization with one addition: you must add a certain reference.

When creating the class whose objects would be serialized, mark it with the [Serializable] attribute. Here is an example:

[Serializable]
public class Car
{
    public string Make;
    public string Model;
    public uint   Year;
    public byte Color;
}

To support SOAP serialization, the .NET Framework provides the SoapFormatter class. This class is defined in the System.Runtime.Serialization.Formatters.Soap namespace that is part of the System.Runtime.Serialization.Formatters.Soap.dll assembly. In order to use The SoapFormatter class, you must reference this assembly. Then, you can create an object and initialize it as you see fit. Before saving it, as always, create a Stream-based object that would indicate the name (and location) of the file and the type of action to perform. Then, declare a SoapFormatter variable using its default constructor. To actually save the object, call the Serialize() method of this class. This method uses the same syntax as that of the BinaryFormatter class: it takes two arguments. The first is a Stream-based object. The second is the object that needs to be serialized.

1. To create a new class, on the main menu, click Project -> Add Class...
2. Set the Name to LoanInformation and click Add
3. Change the file as follows:
   

   using System;
   using System.Collections.Generic;
   using System.Linq;
   using System.Text;
   
   namespace WattsALoan3
   {
       [Serializable]
       public class LoanInformation
       {
           public string EmployeeName;
           public string CustomerFirstName;
           public string CustomerLastName;
           public double Principal;
           public double InterestRate;
           public double Periods;
           public int PeriodType;
       }
   }

4. To add SOAP support to your project, on the main menu, click Project -> Add Reference...
5. In the Add Reference dialog box and in the .NET tab, scroll down and select System.Runtime.Serialization.Formatters.Soap:
    
   
6. Click OK
7. On the form, double-click the Save button
8. In the top section of the form, type the following:
   

   using System;
   using System.Collections.Generic;
   using System.ComponentModel;
   using System.Data;
   using System.Drawing;
   using System.Linq;
   using System.Text;
   using System.Windows.Forms;
   using System.IO;
   using System.Runtime.Serialization.Formatters.Soap;

9. Scroll down and implement the event as follows:
   

   private void btnSave_Click(object sender, EventArgs e)
   {
       if (txtSave.Text.Length == 0)
       {
           MessageBox.Show("Please enter the customer " +
   			"initials or a name for the loan");
           txtSave.Focus();
           return;
       }
   
       var infLoan = new LoanInformation();
   
       infLoan.EmployeeName = txtEmployeeName.Text;
       infLoan.CustomerFirstName = txtCustomerFirstName.Text;
       infLoan.CustomerLastName = txtCustomerLastName.Text;
       infLoan.Principal = double.Parse(txtPrincipal.Text);
       infLoan.InterestRate = double.Parse(txtInterestRate.Text);
       infLoan.Periods = double.Parse(txtPeriods.Text);
       infLoan.PeriodType = cbxPeriods.SelectedIndex;
   
       var stmLoan = new FileStream(txtSave.Text, FileMode.Create,
                                           FileAccess.Write);
       var sfmLoan = new SoapFormatter();
   
       try
       {
           sfmLoan.Serialize(stmLoan, infLoan);
   
           txtEmployeeName.Text = "";
           txtCustomerFirstName.Text = "";
           txtCustomerLastName.Text = "";
           txtPrincipal.Text = "0.00";
           txtInterestRate.Text = "0.00";
           txtPeriods.Text = "0";
           cbxPeriods.SelectedIndex = 0;
           txtFutureValue.Text = "0.00";
           txtInterestEarned.Text = "0.00";
           txtSave.Text = "";
           txtOpen.Text = "";
           txtEmployeeName.Focus();
       }
       finally
       {
           stmLoan.Close();
       }
   }

10. Press Ctrl + F5 to execute the application
11. Create, calculate, and save a few loans
     
12. Close the form and return to your programming environment

De-serialization in soap is performed exactly as done for the binary de-serialization. To support it, the SoapFormatter class is equipped with the Deserialize() method. This method uses the same syntax as its equivalent of the BinaryFormatter class. The approach to use it is also the same.

1. To deserialize, on the form, double-click the Open button and implement its event as follows:
   

   private void btnOpen_Click(object sender, EventArgs e)
   {
       if (txtOpen.Text.Length == 0)
       {
           MessageBox.Show("Please enter a customer's initials or " +
                           "a name given to a previous loan preparation");
           txtOpen.Focus();
           return;
       }
   
       try
       {
           var infLoan = new LoanInformation();
           var stmLoan = new FileStream(txtOpen.Text,
                                        FileMode.Open,
                                        FileAccess.ReadWrite);
           var sfmLoan = new SoapFormatter();
   
           try
           {
               // Open the file and store its values 
               // in the LoanInformation variable
               infLoan = (LoanInformation)sfmLoan.Deserialize(stmLoan);
   
               // Retrive each value and put it in its corresponding control
               txtEmployeeName.Text = infLoan.EmployeeName;
               txtCustomerFirstName.Text = infLoan.CustomerFirstName;
               txtCustomerLastName.Text = infLoan.CustomerLastName;
               txtPrincipal.Text = infLoan.Principal.ToString("F");
               txtInterestRate.Text = infLoan.InterestRate.ToString("F");
               txtPeriods.Text = infLoan.Periods.ToString();
               cbxPeriods.SelectedIndex = infLoan.PeriodType;
   
               // Since we didn't save the calculated values,
               // call the Click event of the Calculate button
               btnCalculate_Click(sender, e);
           }
           finally
           {
               stmLoan.Close();
           }
       }
       catch (FileNotFoundException)
       {
           MessageBox.Show("There is no file with that name");
       }
   }

2. Return to the form and double-click the Close button
3. Implement its Click event as follows:
   

   private void btnClose_Click(object sender, EventArgs e)
   {
       Close();
   }

4. Press Ctrl + F5 to execute the application
5. Enter the initials of a previously created loan and click Open
    
   
6. Close the form and return to your programming environment

In the examples we have used so far, we were saving the whole object. You can make it possible to save only some parts of the class. When creating a class, you can specify what fields would be serialized and which ones would not be. To specify that a member cannot be saved, you can mark it with the [NonSerialized] attribute. Here is an example:

[Serializable]
public class Car
{
    public string Make;
    public string Model;

    // Because the value of a car can change,
    // there is no reason to save it
    [NonSerialized]
    public decimal Value;
    public uint Year;
    public byte Color;
}

After creating the class, you can declare a variable of it and serialize it, using either the binary or the SOAP approach. You can then retrieve the object and its values, using any of the techniques we learned earlier.

To support serialization, the .NET Framework provides the ISerializable interface. You can create a class that implements this interface to customize the serialization process. Even if you plan to use this interface, the class you create must be marked with the [Serializable] attribute.

The .NET Framework is filled with many classes ready for serialization. To know that a class is ready for serialization, when viewing its documentation either in the MSDN web site or in the help documentation, check that it is marked with the [SerializableAttribute]. Here is an example of such as class:

Some of these classes provide the properties and methods to create an object and directly save it. For some other classes, you must first create a class, mark it with the [Serializable] attribute, build an object of it, and then pass it to the .NET class.