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Serialization

 

Object Serialization and De-Serialization

 

Introduction

Consider the following program:

using namespace System;
using namespace System::IO;

int main()
{
    String ^ Make  = L"Ford";
    String ^ Model = L"Escort";
    int Year       = 1998;
    int Color      = 1;

    FileStream ^ stmCar   = gcnew FileStream(L"FordEscort.car",
                                             FileMode::Create);
    BinaryWriter ^ bnwCar = gcnew BinaryWriter(stmCar);

    try {
        bnwCar->Write(Make);
        bnwCar->Write(Model);
        bnwCar->Write(Year);
        bnwCar->Write(Color);
    }
    finally
    {
        bnwCar->Close();
        stmCar->Close();
    }

    return 0;
}

This is an example of the techniques we have used in previous lessons to save individual data of primitive types:

Saving the variables in a method

The values can be retrieved with the following code:

using namespace System;
using namespace System::IO;

int main()
{
    String ^Make, ^Model;
    int Year, Color;

    FileStream ^ stmCar   = gcnew FileStream(L"FordEscort.car",
                                             FileMode::Open);
    BinaryReader ^ bnrCar = gcnew BinaryReader(stmCar);

    try {
        Console::WriteLine(L"Make:  {0}", bnrCar->ReadString());
        Console::WriteLine(L"Model: {0}", bnrCar->ReadString());
        Console::WriteLine(L"Year:  {0}", bnrCar->ReadInt32());
        Console::Write(L"Color: ");
        int clr = bnrCar->ReadInt32();

        switch(clr)
        {
        case 1:
            Console::WriteLine(L"Black");
            break;
        case 2:
            Console::WriteLine(L"Gray");
            break;
        case 3:
            Console::WriteLine(L"White");
            break;
        case 4:
            Console::WriteLine(L"Red");
            break;
        case 5:
            Console::WriteLine(L"Blue");
            break;
        }
    }
    finally
    {
        bnrCar->Close();
        stmCar->Close();
    }

    return 0;
}

This would produce:

Make:  Ford
Model: Escort
Year:  1998
Color: Black
Press any key to continue . . .

In the same way, we learned to save the individual fields of a class:

Saving the individual parts of an object

Here is an example:

using namespace System;
using namespace System::IO;

public ref class CCar
{
public:
    String ^ Make;
    String ^ Model;
    int      Year;
    int      Color;

    CCar();
};

CCar::CCar()
{
    Make  = L"Toyota";
    Model = L"Corolla";
    Year  = 2002;
    Color = 2;
}

int main()
{
    CCar ^ vehicle = gcnew CCar;
        
    FileStream ^ stmCar   = File::Create(L"ToyotaCorolla.car");
    BinaryWriter ^ bnwCar = gcnew BinaryWriter(stmCar);

    try	{
        bnwCar->Write(vehicle->Model);
        bnwCar->Write(vehicle->Year);
        bnwCar->Write(vehicle->Color);
    }
    finally
    {
        bnwCar->Close();
        stmCar->Close();
    }

    return 0;
}

When it comes to a class, the problem with saving individual fields is that you could forget to save one of the fields. For example, considering a Car class, if you don't save the Make information of a Car object and retrieve or open the saved object on another computer, the receiving user would miss some information and the car cannot be completely identifiable. An alternative is to save the whole Car object.

Object serialization consists of saving a whole object as one instead of its individual fields:

Serialization

In other words, a variable declared from a class can be saved to a stream and then the saved object can be retrieved later or on another computer. The .NET Framework supports two types of object serialization: binary and SOAP.

Practical Learning: Introducing Serialization

  1. Start Microsoft Visual C++ and create a new CLR empty project named GeorgetownCleaningServices7
  2. To add a new source file to the project, on the main menu, click Project -> Add New Item...
  3. In the Templates list, click C++ File (.cpp)
  4. Set the Name to Exercise and click Add
  5. In the empty document, type the following:
     
    using namespace System;
    using namespace System::IO;
    
    void HireEmployee()
    {
        FileStream ^ fsEmployee = nullptr;
        BinaryWriter ^ bwEmployee = nullptr;
    
        // Ask the clerk to enter an employee number
        // using the format 00-000
        Console::Write(L"Enter Employee Number (00-000): ");
        String ^emplNumber = Console::ReadLine();
    
        String ^ strPath = L"C:\\Georgetown Cleaning Services\\Employees\\"
                           + emplNumber + L".gce";
    
        if( File::Exists(strPath) )
        {
            Console::Write(L"\nEither the employee has already been hired, ");
            Console::WriteLine(L"or there is already another employee with that number.");
            return;
        }
        else // If no employee with that number was found, create it
        {
            try {
                // If there is not yet a directory named Employees, then create it
                Directory::CreateDirectory(L"C:\\Georgetown Cleaning Services\\Employees");
            }
            catch(DirectoryNotFoundException ^)
            {
                Console::WriteLine(L"The folder could not be created");
            }
    
            try {
                fsEmployee = File::Create(strPath);
                bwEmployee = gcnew BinaryWriter(fsEmployee);
                Console::Write(L"Enter Employee First Name: ");
                String ^emplFName = Console::ReadLine();
                Console::Write(L"Enter Employee Last Name:  ");
                String ^emplLName = Console::ReadLine();
                Console::Write(L"Enter Hourly Salary: ");
                double emplSalary = double::Parse(Console::ReadLine());
    
                // The minimum salary in this company is 7.50
                if( emplSalary < 7.50 )
                    emplSalary = 7.50;
    
                bwEmployee->Write(emplNumber);
                bwEmployee->Write(emplFName);
                bwEmployee->Write(emplLName);
                bwEmployee->Write(emplSalary);
            }
            finally
            {
                bwEmployee->Close();
                fsEmployee->Close();
            }
        }
                
        Console::WriteLine();
    }       
    
    int main()
    {
        wchar_t answer = L'0';
    
        do {
            try {
                Console::WriteLine(L"What do you want to do?");
                Console::WriteLine(L"0. Quit");
                Console::WriteLine(L"1. Hire a new employee");
                Console::WriteLine(L"2. Process a payroll");
                Console::Write(L"Your Choice: ");
    			answer = wchar_t::Parse(Console::ReadLine());
            }
            catch(FormatException ^)
            {
                Console::WriteLine(L"Invalid Answer!");
            }
    
            switch(answer)
            {
            case L'1':
                HireEmployee();
                break;
    
            case L'2':
                break;
    
            default:
                break;
            }
        } while (answer == L'1' || answer == L'2');
    
        Console::WriteLine();
        return 0;
    }
  6. Execute the application and test it. Here is an example:
     
    What do you want to do?
    0. Quit
    1. Hire a new employee
    2. Process a payroll
    Your Choice: 1
    Enter Employee Number (00-000): 86-225
    Enter Employee First Name: Anne
    Enter Employee Last Name: Harang
    Enter Hourly Salary: 16.75
    
    What do you want to do?
    0. Quit
    1. Hire a new employee
    2. Process a payroll
    Your Choice: 1
    Enter Employee Number (00-000): 42-713
    Enter Employee First Name: Peter
    Enter Employee Last Name: Lansome
    Enter Hourly Salary: 12.45
    
    What do you want to do?
    0. Quit
    1. Hire a new employee
    2. Process a payroll
    Your Choice: 1
    Enter Employee Number (00-000): 29-368
    Enter Employee First Name: Gertrude
    Enter Employee Last Name: Monay
    Enter Hourly Salary: 10.85
    
    What do you want to do?
    0. Quit
    1. Hire a new employee
    2. Process a payroll
    Your Choice: 0
    
    Press any key to continue . . .
  7. Close the DOS window

Serialization

Binary serialization works by processing an object rather than streaming its individual member variables. This means that, to use it, you define an object and initialize it, or "fill" it, with the necessary values and any information you judge necessary. This creates a "state" of the object. It is this state that you prepare to serialize. When you save the object, it is converted into a stream.

To perform binary serialization, there are a few steps you must follow. When creating the class whose objects would be serialized, start it with the [Serializable] attribute. Here is an example:

[Serializable]
public ref class CCar
{
public:
    String ^ Make;
    String ^ Model;
    int      Year;
    int      Color;

    CCar();
};

Before serializing an object, you should reference the System::Runtime::Serialization::Formatters::Binary namespace. The class responsible for binary serialization is called BinaryFormatter. This class is equipped with two constructors. The default constructor is used to simply create an object. After declaring the variable, to actually serialize an object, call the Serialize() method of the BinaryFormatter class. The method is overloaded with two versions. One of the versions of this method uses the following syntax:

public:
    virtual void Serialize(Stream ^ serializationStream,
			   Object ^ graph) sealed;

The first argument to this method must be an object of a Stream-based class. In the previous lessons, we saw how to create Stream objects (for example using the FileStream class).

The second argument must be the object to serialize. This means that, before calling this method, you should have built the object.

Here is an example:

using namespace System;
using namespace System::IO;
using namespace System::Runtime::Serialization::Formatters::Binary;

[Serializable]
public ref class CCar
{
public:
    String ^ Make;
    String ^ Model;
    int      Year;
    int      Color;
};

int main()
{
    CCar ^ vehicle = gcnew CCar;

    vehicle->Make  = L"Lexus";
    vehicle->Model = L"LS";
    vehicle->Year  = 2007;
    vehicle->Color = 4;

    FileStream ^ stmCar   = gcnew FileStream(L"LexusLS.car",
                                             FileMode::Create);
    BinaryFormatter ^ bfmCar = gcnew BinaryFormatter;
        
    bfmCar->Serialize(stmCar, vehicle);
    return 0;
}

Practical Learning: Serializing an Object

  1. To create a new class, in the Class View, right-click GeorgetownCleaningServices7 -> Add -> Class...
  2. In the Templates list, click C++ Class and click Add
  3. Set the Name to CPayrollInformation and click Finish
  4. Change the PayrollInformation.h header file as follows:
     
    #pragma once
    
    using namespace System;
    
    [Serializable]
    public ref class CPayrollInformation
    {
    private:
    	String ^ number;
        String ^ fname;
        String ^ lname;
        double salary;
        DateTime start;
    
    public:
    	CPayrollInformation(void);
    
    	property String ^ EmployeeNumber
        {
            String ^ get() { return this->number; }
            void set(String ^ value) { this->number = value; }
        }
    
        property String ^ FirstName
        {
            String ^ get() { return this->fname; }
            void set(String ^ value) { this->fname = value; }
        }
    
        property String ^ LastName
        {
            String ^ get() { return this->lname; }
            void set(String ^ value) { this->lname = value; }
        }
    
        property double HourlySalary
        {
            double get() { return this->salary; }
            void set(double value) { this->salary = value; }
        }
    
        property DateTime StartPeriod
        {
            DateTime get() { return this->start; }
            void set(DateTime value) { this->start = value; }
        }
    
        property DateTime EndPeriod
        {
            DateTime get() { return start.AddDays(13); }
        }
    
        double Week1Monday;
        double Week1Tuesday;
        double Week1Wednesday;
        double Week1Thursday;
        double Week1Friday;
        double Week2Monday;
        double Week2Tuesday;
        double Week2Wednesday;
        double Week2Thursday;
        double Week2Friday;
    
        double RegularHours;
        double OvertimeHours;
        double RegularAmount;
        double OvertimeAmount;
        double TotalEarnings;
    };
  5. Access the Exercise.cpp source file and change it as follows:
     
    #include "PayrollInformation.h"
    
    using namespace System;
    using namespace System::IO;
    using namespace System::Runtime::Serialization::Formatters::Binary;
    
    void HireEmployee();
    void CreatePayroll();
    void SavePayroll(CPayrollInformation ^ pay);
    void ShowPayroll(CPayrollInformation ^ payed);
    
    void HireEmployee()
    {
        FileStream ^ fsEmployee = nullptr;
        BinaryWriter ^ bwEmployee = nullptr;
    
        // Ask the clerk to enter an employee number
        // using the format 00-000
        Console::Write(L"Enter Employee Number (00-000): ");
        String ^emplNumber = Console::ReadLine();
    
        String ^ strPath = L"C:\\Georgetown Cleaning Services\\Employees\\"
                           + emplNumber + L".gce";
    
        if( File::Exists(strPath) )
        {
            Console::Write(L"\nEither the employee has already been hired, ");
            Console::WriteLine(L"or there is already another employee with that number.");
            return;
        }
        else // If no employee with that number was found, create it
        {
            try {
                // If there is not yet a directory named Employees, then create it
                Directory::CreateDirectory(L"C:\\Georgetown Cleaning Services\\Employees");
            }
            catch(DirectoryNotFoundException ^)
            {
                Console::WriteLine(L"The folder could not be created");
            }
    
            try {
                fsEmployee = File::Create(strPath);
                bwEmployee = gcnew BinaryWriter(fsEmployee);
                Console::Write(L"Enter Employee First Name: ");
                String ^emplFName = Console::ReadLine();
                Console::Write(L"Enter Employee Last Name:  ");
                String ^emplLName = Console::ReadLine();
                Console::Write(L"Enter Hourly Salary: ");
                double emplSalary = double::Parse(Console::ReadLine());
    
                // The minimum salary in this company is 7.50
                if( emplSalary < 7.50 )
                    emplSalary = 7.50;
    
                bwEmployee->Write(emplNumber);
                bwEmployee->Write(emplFName);
                bwEmployee->Write(emplLName);
                bwEmployee->Write(emplSalary);
            }
            finally
            {
                bwEmployee->Close();
                fsEmployee->Close();
            }
        }
                
        Console::WriteLine();
    }
    
    void CreatePayroll()
    {
        FileStream ^   fsPayroll = nullptr;
        BinaryReader ^ brPayroll = nullptr;
        DateTime dteStartDate;
    
        CPayrollInformation ^ payroll = gcnew CPayrollInformation();
    
        double monday1 = 0.00, tuesday1 = 0.00,
               wednesday1 = 0.00, thursday1 = 0.00,
               friday1 = 0.00, monday2 = 0.00,
               tuesday2 = 0.00, wednesday2 = 0.00,
               thursday2 = 0.00, friday2 = 0.00;
        double totalHoursWeek1 = 0.00,
               totalHoursWeek2 = 0.00;
    
        double regHours1 = 0.00, regHours2 = 0.00,
               ovtHours1 = 0.00, ovtHours2 = 0.00;
        double regAmount1 = 0.00, regAmount2 = 0.00,
               ovtAmount1 = 0.00, ovtAmount2 = 0.00;
        double regularHours = 0.00, overtimeHours = 0.00;
        double regularAmount = 0.00,
               overtimeAmount = 0.00,
               totalEarnings = 0.00;
    
        Console::Write(L"Enter Employee Number: ");
        String ^emplNumber = Console::ReadLine();
    
        String ^ strEmployeePath = L"C:\\Georgetown " 
                                   L"Cleaning Services\\Employees\\" 
                                   + emplNumber + ".gce";
    
        if( !File::Exists(strEmployeePath) )
        {
            Console::WriteLine(L"There is no employee with " 
                               L"that number in our records");
            return;
        }
        // If an employee with that number was found,
        // continue with the payroll
        else
        {
            try {
                fsPayroll = gcnew FileStream(strEmployeePath,
                                             FileMode::Open,
                                             FileAccess::Read);
                brPayroll = gcnew BinaryReader(fsPayroll);
    
                payroll->EmployeeNumber = brPayroll->ReadString();
                payroll->FirstName = brPayroll->ReadString();
                payroll->LastName = brPayroll->ReadString();
                payroll->HourlySalary = brPayroll->ReadDouble();
    
                Console::WriteLine(L"\n------------------------" 
                                          L"------------------------");
                Console::WriteLine(L"Employee #:    {0}",
                                   payroll->EmployeeNumber);
                Console::WriteLine(L"Full Name:     {0}, {1}",
                                   payroll->LastName,
                                   payroll->FirstName);
                Console::WriteLine(L"Hourly Salary: {0:C}",
                                   payroll->HourlySalary);
                Console::WriteLine(L"-------------------------" 
                                          L"-----------------------\n");
            }
            finally
            {
                brPayroll->Close();
                fsPayroll->Close();
            }
    
            try {
                do {
                    Console::Write(L"Enter Payroll Start " 
                                   L"Date (mm/dd/yyyy): ");
    				dteStartDate = DateTime::Parse(Console::ReadLine());
    
    				if( dteStartDate.DayOfWeek != DayOfWeek::Sunday )
                    {
                        Console::WriteLine(L"Invalid Date Entry");
                        Console::WriteLine(L"Payrolls start " 
                                           L"on a Sunday");
                    }
                } while (dteStartDate.DayOfWeek !=
    				DayOfWeek::Sunday);
    
                payroll->StartPeriod = dteStartDate;
            }
            catch(FormatException ^)
            {
                Console::WriteLine(L"Invalid Date Entry");
            }
        }
    
        // Retrieve the value of each day worked
        Console::WriteLine(L"\nEnter the time worked " 
                           L"for each day (0.00)");
        Console::WriteLine(L"=-= Week 1 =-=");
        try {
            Console::Write(L"{0}: ",
                        payroll->StartPeriod.AddDays(1).ToString(L"D"));
            monday1 = double::Parse(Console::ReadLine());
        }
        catch(FormatException ^)
        {
            Console::WriteLine(L"You typed an invalid value");
        }
    
        try {
            Console::Write(L"{0}: ",
                    payroll->StartPeriod.AddDays(2).ToString(L"D"));
            tuesday1 = double::Parse(Console::ReadLine());
        }
        catch(FormatException ^)
        {
            Console::WriteLine(L"You typed an invalid value");
        }
    
        try {
            Console::Write(L"{0}: ",
                        payroll->StartPeriod.AddDays(3).ToString(L"D"));
            wednesday1 = double::Parse(Console::ReadLine());
        }
        catch(FormatException ^)
        {
            Console::WriteLine(L"You typed an invalid value");
        }
    
        try {
            Console::Write(L"{0}: ",
                        payroll->StartPeriod.AddDays(4).ToString(L"D"));
            thursday1 = double::Parse(Console::ReadLine());
        }
        catch(FormatException ^)
        {
            Console::WriteLine(L"You typed an invalid value");
        }
    
        try {
            Console::Write(L"{0}: ",
                        payroll->StartPeriod.AddDays(5).ToString(L"D"));
            friday1 = double::Parse(Console::ReadLine());
        }
        catch(FormatException ^)
        {
            Console::WriteLine(L"You typed an invalid value");
        }
    
        Console::WriteLine(L"=-= Week 2 =-=");
        try {
            Console::Write(L"{0}: ",
                     payroll->StartPeriod.AddDays(8).ToString(L"D"));
            monday2 = double::Parse(Console::ReadLine());
        }
        catch(FormatException ^)
        {
            Console::WriteLine(L"You typed an invalid value");
        }
        
        try {
            Console::Write(L"{0}: ",
                      payroll->StartPeriod.AddDays(9).ToString(L"D"));
            tuesday2 = double::Parse(Console::ReadLine());
        }
        catch(FormatException ^)
        {
            Console::WriteLine(L"You typed an invalid value");
        }
    
        try {
            Console::Write(L"{0}: ",
                     payroll->StartPeriod.AddDays(10).ToString(L"D"));
            wednesday2 = double::Parse(Console::ReadLine());
        }
        catch(FormatException ^)
        {
            Console::WriteLine(L"You typed an invalid value");
        }
    
        try {
            Console::Write(L"{0}: ",
                        payroll->StartPeriod.AddDays(11).ToString(L"D"));
            thursday2 = double::Parse(Console::ReadLine());
        }
        catch(FormatException ^)
        {
            Console::WriteLine(L"You typed an invalid value");
        }
       
        try {
            Console::Write(L"{0}: ",
                        payroll->StartPeriod.AddDays(12).ToString(L"D"));
            friday2 = double::Parse(Console::ReadLine());
        }
        catch(FormatException ^)
        {
            Console::WriteLine(L"You typed an invalid value");
        }
    
        // Calculate the total number of hours for each week
        totalHoursWeek1 = monday1 + tuesday1 + wednesday1 +
                          thursday1 + friday1;
        totalHoursWeek2 = monday2 + tuesday2 + wednesday2 +
                                  thursday2 + friday2;
    
        // The overtime is paid time and half
        double ovtSalary = payroll->HourlySalary * 1.5;
    
        // If the employee worked under 40 hours,
        // there is no overtime
        if( totalHoursWeek1 < 40 )
        {
            regHours1 = totalHoursWeek1;
            regAmount1 = payroll->HourlySalary * regHours1;
            ovtHours1 = 0.00;
            ovtAmount1 = 0.00;
        } // If the employee worked over 40 hours,
        // calculate the overtime
        else if( totalHoursWeek1 >= 40 )
        {
            regHours1 = 40;
            regAmount1 = payroll->HourlySalary * 40;
            ovtHours1 = totalHoursWeek1 - 40;
            ovtAmount1 = ovtHours1 * ovtSalary;
        }
    
        if( totalHoursWeek2 < 40 )
        {
            regHours2 = totalHoursWeek2;
            regAmount2 = payroll->HourlySalary * regHours2;
            ovtHours2 = 0.00;
            ovtAmount2 = 0.00;
        }
        else if( totalHoursWeek2 >= 40 )
        {
            regHours2 = 40;
            regAmount2 = payroll->HourlySalary * 40;
            ovtHours2 = totalHoursWeek2 - 40;
            ovtAmount2 = ovtHours2 * ovtSalary;
        }
    
        regularHours = regHours1 + regHours2;
        overtimeHours = ovtHours1 + ovtHours2;
        regularAmount = regAmount1 + regAmount2;
        overtimeAmount = ovtAmount1 + ovtAmount2;
        totalEarnings = regularAmount + overtimeAmount;
    
        payroll->Week1Monday = monday1;
        payroll->Week1Tuesday = tuesday1;
        payroll->Week1Wednesday = wednesday1;
        payroll->Week1Thursday = thursday1;
        payroll->Week1Friday = friday1;
    
        payroll->Week2Monday = monday2;
        payroll->Week2Tuesday = tuesday2;
        payroll->Week2Wednesday = wednesday2;
        payroll->Week2Thursday = thursday2;
        payroll->Week2Friday = friday2;
    
        payroll->RegularHours = regularHours;
        payroll->OvertimeHours = overtimeHours;
        payroll->RegularAmount = regularAmount;
        payroll->OvertimeAmount = overtimeAmount;
        payroll->TotalEarnings = totalEarnings;
    
        ShowPayroll(payroll);
    
        Console::Write(L"Do you want to save " 
                       L"the payroll (y/n): ");
        String ^ strAnswer = Console::ReadLine();
    
        if( strAnswer->ToUpper() == L"Y")
            SavePayroll(payroll);
    }
    
    void SavePayroll(CPayrollInformation ^ pay)
    {
        // We will need this value to create the
        // name of the payroll file
        String ^ strMonth = L"0", ^strDay = L"0", ^strYear = L"0";
    
        // We want the month and day to include 0 if necessary
        strMonth = pay->StartPeriod.Month.ToString();
        
    	if( pay->StartPeriod.Month < 10 )
            strMonth = L"0" + pay->StartPeriod.Month.ToString();
    
        strDay = pay->StartPeriod.Day.ToString();
    	if( pay->StartPeriod.Day < 10 )
            strDay = L"0" + pay->StartPeriod.Day.ToString();
    
        strYear = pay->StartPeriod.Year.ToString();
    
    	String ^ strPayrollFilename = L"C:\\Georgetown " 
                                      L"Cleaning Services\\Payrolls\\" 
                                      + pay->LastName[0] +
                                      pay->FirstName[0] +
                                      strMonth + strDay +
                                      strYear + ".epr";
         
    	try {
    		// If there is not yet a directory for the 
    		// payrolls, then create it
    		Directory::CreateDirectory(L"C:\\Georgetown Cleaning " 
                                       L"Services\\Payrolls");
        }
    	catch(DirectoryNotFoundException ^)
        {
             Console::WriteLine(L"The employee payroll file " 
                                L"could not be created");
        }
    
        if( File::Exists(strPayrollFilename) )
        {
            Console::WriteLine(L"The employee's payroll " 
                               L"for that period exists already");
        }
    
    	FileStream ^ fsEmployeePayroll =
                                     gcnew FileStream(strPayrollFilename,
                                     FileMode::Create);
        BinaryFormatter ^ bfEmployeePayroll =
                    gcnew BinaryFormatter();
    
        bfEmployeePayroll->Serialize(fsEmployeePayroll, pay);
        fsEmployeePayroll->Close();
    }
    
    void ShowPayroll(CPayrollInformation ^ payed)
    {
        Console::WriteLine(L"\n=============================" 
                           L"===================");
        Console::WriteLine(L"=$= Payroll summary =$=");
        Console::WriteLine(L"-------------------------------" 
                           L"-----------------");
        Console::WriteLine(L"Employee #:    {0}",
                           payed->EmployeeNumber);
        Console::WriteLine(L"Full Name:     {0}, {1}",
                           payed->FirstName, payed->LastName);
        Console::WriteLine(L"Hourly Salary: {0:C}",
                           payed->HourlySalary);
        Console::WriteLine(L"Start Period:  {0:D}",
                                  payed->StartPeriod);
        Console::WriteLine(L"End Period:    {0:D}",
                                  payed->EndPeriod);
        Console::WriteLine(L"--------------------------------" 
                                  L"----------------");
        Console::WriteLine(L"        Monday Tuesday Wednesday " 
                                  L"Thursday Friday");
        Console::WriteLine(L"Week 1:  {0:F}   {1:F}     " 
                                  L"{2:F}      {3:F}    {4:F}",
                                  payed->Week1Monday, payed->Week1Tuesday,
                                  payed->Week1Wednesday, payed->Week1Thursday,
                                  payed->Week1Friday);
        Console::WriteLine(L"Week 2:  {0:F}   {1:F}     " 
                                  L"{2:F}      {3:F}    {4:F}",
                                  payed->Week2Monday, payed->Week2Tuesday,
                                  payed->Week2Wednesday, payed->Week2Thursday,
                                  payed->Week2Friday);
        Console::WriteLine(L"-------------------------------" 
                                  L"-----------------");
        Console::WriteLine(L"Monetary Summary");
        Console::WriteLine(L"            Hours   Amount");
        Console::WriteLine(L"Regular:   {0,6}   {1,6}",
                                  payed->RegularHours.ToString(L"F"),
                                  payed->RegularAmount.ToString(L"F"));
        Console::WriteLine(L"Overtime:  {0,6}   {1,6}",
                                  payed->OvertimeHours.ToString(L"F"),
                                  payed->OvertimeAmount.ToString(L"F"));
        Console::WriteLine(L"-------------------------------" 
                                  L"-----------------");
        Console::WriteLine(L"Net Pay:   {0:F}",
                                  payed->TotalEarnings);
        Console::WriteLine(L"===============================" 
                                  L"=================\n");
    }     
    
    void ViewPayroll()
    {
    }
    
    int main()
    {
        wchar_t answer = L'0';
    
        Console::WriteLine(L"========================" 
                           L"========================");
        Console::WriteLine(L"Georgetown Cleaning Services");
        Console::WriteLine(L"========================" 
                           L"========================");
    
        do {
           try {
                Console::WriteLine(L"\nWhat do you want to do?");
                Console::WriteLine(L"0. Quit");
                Console::WriteLine(L"1. Hire a new employee");
                Console::WriteLine(L"2. Process a payroll");
                Console::WriteLine(L"3. View an employee's payroll");
                Console::Write(L"Your Choice: ");
                answer = wchar_t::Parse(Console::ReadLine());
                Console::WriteLine();
            }
            catch(FormatException ^)
            {
                Console::WriteLine(L"Invalid Answer!");
            }
    
            switch(answer)
            {
            case L'1':
                HireEmployee();
                break;
            case L'2':
                CreatePayroll();
                break;
            case L'3':
                ViewPayroll();
                break;
            default:
                break;
            }
    
        } while( (answer == L'1') ||
                 (answer == L'2') ||
                 (answer == L'3') );
    
        Console::WriteLine();
        return 0;
    }
  6. Execute the application and test it. Here is an example:
     
    ================================================
    Georgetown Cleaning Services
    ================================================
    
    What do you want to do?
    0. Quit
    1. Hire a new employee
    2. Process a payroll
    3. View an employee's payroll
    Your Choice: 2
    
    Enter Employee Number: 29-368
    
    ------------------------------------------------
    Employee #:    29-368
    Full Name:     Monay, Gertrude
    Hourly Salary: $10.85
    ------------------------------------------------
    
    Enter Payroll Start Date (mm/dd/yyyy): 11/12/05
    Invalid Date Entry
    Payrolls start on a Sunday
    Enter Payroll Start Date (mm/dd/yyyy): 11/12/06
    
    Enter the time worked for each day (0.00)
    =-= Week 1 =-=
    Monday, November 13, 2006: 8.00
    Tuesday, November 14, 2006: 8.50
    Wednesday, November 15, 2006: 9.50
    Thursday, November 16, 2006: 8
    Friday, November 17, 2006: 8.50
    =-= Week 2 =-=
    Monday, November 20, 2006: 6.50
    Tuesday, November 21, 2006: 7.00
    Wednesday, November 22, 2006: 8
    Thursday, November 23, 2006: 6.00
    Friday, November 24, 2006: 7.00
    
    ================================================
    =$= Payroll summary =$=
    ------------------------------------------------
    Employee #:    29-368
    Full Name:     Monay, Gertrude
    Hourly Salary: $10.85
    Start Period:  Sunday, November 12, 2006
    End Period:    Saturday, November 25, 2006
    ------------------------------------------------
            Monday Tuesday Wednesday Thursday Friday
    Week 1:  8.00   8.50     9.50      8.00    8.50
    Week 2:  6.50   7.00     8.00      6.00    7.00
    ------------------------------------------------
    Monetary Summary
                Hours   Amount
    Regular:    74.50   808.33
    Overtime:    2.50    40.69
    ------------------------------------------------
    Net Pay:   849.01
    ================================================
    
    Do you want to save the payroll (y/n): Y
    
    What do you want to do?
    0. Quit
    1. Hire a new employee
    2. Process a payroll
    3. View an employee's payroll
    Your Choice: 0
    
    Press any key to continue . . .
  7. Close the DOS window
  8. Execute the application again and process another payroll. Here is an example:
     
    ================================================
    Georgetown Cleaning Services
    ================================================
    
    What do you want to do?
    0. Quit
    1. Hire a new employee
    2. Process a payroll
    3. View an employee's payroll
    Your Choice: 2
    
    Enter Employee Number: 86-025
    There is no employee with that number in our records
    
    What do you want to do?
    0. Quit
    1. Hire a new employee
    2. Process a payroll
    3. View an employee's payroll
    Your Choice: 2
    
    Enter Employee Number: 86-225
    
    ------------------------------------------------
    Employee #:    86-225
    Full Name:     Harang, Anne
    Hourly Salary: $16.75
    ------------------------------------------------
    
    Enter Payroll Start Date (mm/dd/yyyy): 11/26/2006
    
    Enter the time worked for each day (0.00)
    =-= Week 1 =-=
    Monday, November 27, 2006: 8
    Tuesday, November 28, 2006: 6.5
    Wednesday, November 29, 2006: 8.5
    Thursday, November 30, 2006: 8
    Friday, December 01, 2006: 8
    =-= Week 2 =-=
    Monday, December 04, 2006: 9
    Tuesday, December 05, 2006: 8.5
    Wednesday, December 06, 2006: 8
    Thursday, December 07, 2006: 9.5
    Friday, December 08, 2006: 8.00
    
    ================================================
    =$= Payroll summary =$=
    ------------------------------------------------
    Employee #:    86-225
    Full Name:     Anne, Harang
    Hourly Salary: $16.75
    Start Period:  Sunday, November 26, 2006
    End Period:    Saturday, December 09, 2006
    ------------------------------------------------
            Monday Tuesday Wednesday Thursday Friday
    Week 1:  8.00   6.50     8.50      8.00    8.00
    Week 2:  9.00   8.50     8.00      9.50    8.00
    ------------------------------------------------
    Monetary Summary
                Hours   Amount
    Regular:    79.00   1323.25
    Overtime:    3.00    75.38
    ------------------------------------------------
    Net Pay:   1398.63
    ================================================
    
    Do you want to save the payroll (y/n):
  9. Close the DOS window

De-Serialization

As serialization is the process of storing an object to a medium, the opposite, serialization is used to retrieve an object from a stream. To support this, the BinaryFormatter class is equipped with the Deserialize() method. Like Serialize(), the Deserialize() method is overloaded with two versions. One of them uses the following syntax:

public:
    Object ^ Deserialize(Stream ^ serializationStream) sealed;

This method takes as argument a Stream-based object, such as a FileStream variable, that indicates where the file is located The Deserialize() method. The Deserialize() method returns an Object object. As a goal, you want the Deserialize() method to produce the type of object that was saved so you can retrieve the values that the returned object holds. Because the method returns an Object value, you must cast the returned value to the type of your class.

Once the Deserialize() method has returned the desired object, you can access its values. Here is an example:

using namespace System;
using namespace System::IO;
using namespace System::Runtime::Serialization::Formatters::Binary;

[Serializable]
public ref class CCar
{
public:
    String ^Make;
    String ^Model;
    int Year;
    int Color;
};

int main()
{
    FileStream ^ stmCar   = gcnew FileStream(L"LexusLS.car",
                                             FileMode::Open);
    BinaryFormatter ^ bfmCar = gcnew BinaryFormatter();
    CCar ^ vehicle = dynamic_cast<CCar ^>(bfmCar->Deserialize(stmCar));

    Console::WriteLine(L"Make:  {0}", vehicle->Make);
    Console::WriteLine(L"Model: {0}", vehicle->Model);
    Console::WriteLine(L"Year:  {0}", vehicle->Year);
    Console::Write(L"Color: ");
    int clr = vehicle->Color;
        
    switch(clr)
    {
    case 1:
        Console::WriteLine(L"Black");
        break;
    case 2:
        Console::WriteLine(L"Gray");
        break;
    case 3:
        Console::WriteLine(L"White");
        break;
    case 4:
        Console::WriteLine(L"Red");
        break;
    case 5:
        Console::WriteLine(L"Blue");
        break;
    }
        
    stmCar->Close();

    return 0;
}

This would produce:

Make:  Lexus
Model: LS
Year:  2007
Color: Red
Press any key to continue . . .

Practical Learning: De-Serializing an Object

  1. In the Exercise.cpp file, implement the ViewPayroll() function as follows:
     
    void ViewPayroll()
    {
        String ^ strEmplNumber, ^strFName, ^strLName;
        String ^ strMonth, ^strDay, ^strYear;
    
        // Ask the clerk to enter an employee number
        // using the format 00-000
        Console::Write(L"Enter Employee Number (00-000): ");
        strEmplNumber = Console::ReadLine();
    
        String ^ strFilename = L"C:\\Georgetown Cleaning " 
                               L"Services\\Employees\\" 
                               + strEmplNumber + ".gce";
    
        if( !File::Exists(strFilename) )
        {
            Console::Write(L"There is no employee " 
                           L"with that number.");
        }
        else
        {
            FileStream ^ fsEmployee = nullptr;
            BinaryReader ^ brEmployee = nullptr;
    
            try {
                // We need to formally open the file 
                // because we need the employees initials
                fsEmployee = gcnew FileStream(strFilename,
                                              FileMode::Open,
                                              FileAccess::Read);
                brEmployee = gcnew BinaryReader(fsEmployee);
    
                // Read the file, mainly to get the 
                // employee's name
                strEmplNumber = brEmployee->ReadString();
                strFName = brEmployee->ReadString();
                strLName = brEmployee->ReadString();
            }
            finally
            {
                brEmployee->Close();
                fsEmployee->Close();
            }
    
            Console::Write(L"Enter the start date of the " 
                           L"payroll you want to see (mm/dd/yyyy): ");
            DateTime dteStartDate =
    			DateTime::Parse(Console::ReadLine());
    
            // We want the month and day to include 0 if necessary
            strMonth = dteStartDate.Month.ToString();        
    	if( dteStartDate.Month < 10 )
                strMonth = L"0" + dteStartDate.Month.ToString();
     
    	strDay = dteStartDate.Day.ToString();
    	if( dteStartDate.Day < 10 )
    	    strDay = L"0" + dteStartDate.Day.ToString();
    
    	strYear = dteStartDate.Year.ToString();
    
            strFilename = L"C:\\Georgetown Cleaning " 
                          L"Services\\Payrolls\\" 
                          + strLName[0] +
                                  strFName[0] + strMonth +
                                  strDay + strYear + ".epr";
                    
    	if( !File::Exists(strFilename) )
    	{
    	    Console::Write(L"{0}, {1} doesn't have a " 
                               L"payroll in that time frame",
                               strLName, strFName);
            }
            else
            {
                // Open the payroll and display it
                FileStream ^ fsPayroll =
                            gcnew FileStream(strFilename,
                                             FileMode::Open);
                BinaryFormatter ^ bfPayroll =
                            gcnew BinaryFormatter();
                CPayrollInformation ^ pay =
                            dynamic_cast<CPayrollInformation ^>
    				(bfPayroll->Deserialize(fsPayroll));
    
                ShowPayroll(pay);
            }
        }
    }
  2. Execute the application and test it. Here is an example:
     
    ================================================
    Georgetown Cleaning Services
    ================================================
    
    What do you want to do?
    0. Quit
    1. Hire a new employee
    2. Process a payroll
    3. View an employee's payroll
    Your Choice: 3
    
    Enter Employee Number (00-000): 29-368
    Enter the start date of the payroll you want to see (mm/dd/yyyy): 11/12/06
    
    ================================================
    =$= Payroll summary =$=
    ------------------------------------------------
    Employee #:    29-368
    Full Name:     Gertrude, Monay
    Hourly Salary: $10.85
    Start Period:  Sunday, November 12, 2006
    End Period:    Saturday, November 25, 2006
    ------------------------------------------------
            Monday Tuesday Wednesday Thursday Friday
    Week 1:  8.00   8.50     9.50      8.00    8.50
    Week 2:  6.50   7.00     8.00      6.00    7.00
    ------------------------------------------------
    Monetary Summary
                Hours   Amount
    Regular:    74.50   808.33
    Overtime:    2.50    40.69
    ------------------------------------------------
    Net Pay:   849.01
    ================================================
    
    
    What do you want to do?
    0. Quit
    1. Hire a new employee
    2. Process a payroll
    3. View an employee's payroll
    Your Choice: 0
    
    
    Press any key to continue . . .
  3. Close the DOS window

SOAP Serialization

 

Serialization

The .NET Framework supports another technique of serialization referred to as SOAP (which stands for Simple Object Access Protocol). This technique a little more related to XML but, although we haven't studied XML, you don't need to know anything about it to use SOAP serialization.

To serialize an object using SOAP, you follow the same steps we reviewed for the binary serialization with one addition that 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 ref class CCar
{
public:
    String ^Make;
    String ^Model;
    int Year;
    int 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. You can do this by adding it to your list of references:

Adding a reference to the System.Runtime.Serialization.Formatters.Soap.dll assembly

After these two steps, 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.

Here is an example:

using namespace System;
using namespace System::IO;
using namespace System::Runtime::Serialization::Formatters::Soap;

[Serializable]
public ref class CCar
{
public:
    String ^ Make;
    String ^ Model;
    int Year;
    int Color;
};

int main()
{
    CCar ^ vehicle = gcnew CCar;

    vehicle->Make  = L"Volvo";
    vehicle->Model = L"S40";
    vehicle->Year  = 2006;
    vehicle->Color = 3;

    FileStream ^ stmCar =
            gcnew FileStream(L"VolvoS40.car",
                           FileMode::Create);
    SoapFormatter ^ sopCar = gcnew SoapFormatter();

    sopCar->Serialize(stmCar, vehicle);
    return 0;
}
 

 

 

 

 

 

De-Serialization

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.

Here is an example:

using namespace System;
using namespace System::IO;
using namespace System::Runtime::Serialization::Formatters::Soap;

[Serializable]
public ref class CCar
{
public:
    String ^ Make;
    String ^ Model;
    int Year;
    int Color;
};

int main()
{
    FileStream ^ stmCar =
            gcnew FileStream(L"VolvoS40.car",
                           FileMode::Open);
    SoapFormatter ^ sopCar = gcnew SoapFormatter();
    CCar ^ vehicle = dynamic_cast<CCar ^>(sopCar->Deserialize(stmCar));
        
    Console::WriteLine(L"Car Information");
    Console::WriteLine(L"Make:  {0}", vehicle->Make );
    Console::WriteLine(L"Model: {0}", vehicle->Model);
    Console::WriteLine(L"Year:  {0}", vehicle->Year);
    Console::Write(L"Color: ");
    switch(vehicle->Color)
    {
    case 1:
        Console::WriteLine(L"Black");
        break;
    case 2:
        Console::WriteLine(L"Gray");
        break;
    case 3:
        Console::WriteLine(L"White");
        break;
    case 4:
        Console::WriteLine(L"Red");
        break;
    case 5:
        Console::WriteLine(L"Blue");
        break;
    }
    return 0;
}

This would produce:

Car Information
Make:  Volvo
Model: S40
Year:  2006
Color: White
Press any key to continue . . .

Details on Serialization

 

Partial Serialization

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 ref class CCar
{
public:
    String ^Make;
    String ^Model;

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

After creating the class, you can declare a variable of it and serialize it, using either the binary or the SOAP approach. Here is an example:

using namespace System;
using namespace System::IO;
using namespace System::Runtime::Serialization::Formatters::Binary;

[Serializable]
public ref class CCar
{
public:
    String ^Make;
    String ^Model;

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

int main()
{
        CCar vehicle = gcnew CCar;

        vehicle->Make = L"Lexus";
        vehicle->Model = L"LS";
        vehicle->Year = 2007;
        vehicle->Color = 4;
        vehicle->Value = 28640M;

        FileStream ^ stmCar = gcnew FileStream(L"LexusLS.car",
                                             FileMode::Create);
        BinaryFormatter ^ bfmCar = gcnew BinaryFormatter;

        bfmCar->Serialize(stmCar, vehicle);


        return 0;
    }
}

You can then retrieve the object and its values, using any of the techniques we learned earlier. Here is an example:

using namespace System;
using namespace System::IO;
using namespace System::Runtime::Serialization::Formatters::Binary;

[Serializable]
public ref class CCar
{
public:
    String ^Make;
    String ^Model;

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

int main()
{
    FileStream ^ stmCar = gcnew FileStream(L"LexusLS.car",
                                             FileMode::Open);
    BinaryFormatter bfmCar = new BinaryFormatter();
    CCar ^ vehicle = dynamic_cast<CCar ^>(bfmCar->Deserialize(stmCar));

    Console::WriteLine(L"Car Information");
    Console::WriteLine(L"Make:  {0}", vehicle->Make);
    Console::WriteLine(L"Model: {0}", vehicle->Model);
    Console::WriteLine(L"Year:  {0}", vehicle->Year);
    Console::Write(L"Color: ");
    switch (vehicle->Color)
    {
    case 1:
        Console::WriteLine(L"Black");
        break;
    case 2:
        Console::WriteLine(L"Gray");
        break;
    case 3:
        Console::WriteLine(L"White");
        break;
    case 4:
        Console::WriteLine(L"Red");
        break;
    case 5:
        Console::WriteLine(L"Blue");
        break;
    }
    Console::WriteLine(L"Value:  {0}\n", vehicle->Value);

    return 0;
}

This would produce:

Car Information
Make: Lexus
Model: LS
Year: 2007
Color: Red
Value:  0

Press any key to continue . . .

Notice that the value of the Value field was not saved: it holds the default value of its data type. This indicates that, you can assign a value a [NonSerialized] field and save the object. The value of that field would not be saved but the compiler would not throw an exception.

Implementing a Custom Serialized Class

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.

.NET Built-In Serialized Classes

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:

The Serializable attribute of a built-in 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.


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