Serialization

1. • Definition of Serialization

     Serialization is the process of converting an object into a format that can be stored or transmitted and later reconstructed. This allows objects to be saved to a file, sent over a network, or stored in a database in a way that they can be reconstructed later.

     Uses of Serialization

     1. Persistence – Storing objects in a file or database for later retrieval.

     2. Communication – Transmitting objects over a network (e.g., in distributed applications).

     3. Caching – Storing objects in memory to speed up future access.

     4. Deep Copying – Cloning objects by serializing and deserializing them.

     5. Interoperability – Sharing data between different programming languages or systems.

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     Example in Java

     In Java, serialization is implemented using the Serializable interface.

     import java.io.*;
     
     // Class that implements Serializable
     class Person implements Serializable {
         private static final long serialVersionUID = 1L;  // Ensure versioning compatibility
         String name;
         int age;
     
         // Constructor
         public Person(String name, int age) {
             this.name = name;
             this.age = age;
         }
     
         // Method to display object data
         public void display() {
             System.out.println("Name: " + name + ", Age: " + age);
         }
     }
     
     public class SerializationExample {
         public static void main(String[] args) {
             Person person = new Person("John", 30);
     
             // Serialize the object
             try (FileOutputStream fileOut = new FileOutputStream("person.ser");
                  ObjectOutputStream out = new ObjectOutputStream(fileOut)) {
                 out.writeObject(person);
                 System.out.println("Object serialized successfully.");
             } catch (IOException e) {
                 e.printStackTrace();
             }
     
             // Deserialize the object
             try (FileInputStream fileIn = new FileInputStream("person.ser");
                  ObjectInputStream in = new ObjectInputStream(fileIn)) {
                 Person deserializedPerson = (Person) in.readObject();
                 System.out.println("Object deserialized successfully.");
                 deserializedPerson.display();
             } catch (IOException | ClassNotFoundException e) {
                 e.printStackTrace();
             }
         }
     }
     

     Explanation:

     1. The Person class implements Serializable.

     2. ObjectOutputStream writes the object to a file (person.ser).

     3. ObjectInputStream reads the object back and restores it.

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     Equivalent Example in Python

     In Python, pickle is commonly used for serialization.

     import pickle
     
     # Class definition
     class Person:
         def __init__(self, name, age):
             self.name = name
             self.age = age
     
         def display(self):
             print(f"Name: {self.name}, Age: {self.age}")
     
     # Serialize object
     person = Person("John", 30)
     with open("person.pkl", "wb") as file:
         pickle.dump(person, file)
         print("Object serialized successfully.")
     
     # Deserialize object
     with open("person.pkl", "rb") as file:
         deserialized_person = pickle.load(file)
         print("Object deserialized successfully.")
         deserialized_person.display()
     

     Key Differences:

     • pickle.dump() serializes the object.

     • pickle.load() deserializes the object.

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     Equivalent Example in C#

     In C#, System.Runtime.Serialization and System.Xml.Serialization are used.

     using System;
     using System.IO;
     using System.Runtime.Serialization;
     using System.Runtime.Serialization.Formatters.Binary;
     
     [Serializable]
     class Person
     {
         public string Name { get; set; }
         public int Age { get; set; }
     
         public Person(string name, int age)
         {
             Name = name;
             Age = age;
         }
     
         public void Display()
         {
             Console.WriteLine($"Name: {Name}, Age: {Age}");
         }
     }
     
     class SerializationExample
     {
         static void Main()
         {
             Person person = new Person("John", 30);
             string filePath = "person.dat";
     
             // Serialize object
             IFormatter formatter = new BinaryFormatter();
             using (Stream stream = new FileStream(filePath, FileMode.Create, FileAccess.Write, FileShare.None))
             {
                 formatter.Serialize(stream, person);
                 Console.WriteLine("Object serialized successfully.");
             }
     
             // Deserialize object
             using (Stream stream = new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.Read))
             {
                 Person deserializedPerson = (Person)formatter.Deserialize(stream);
                 Console.WriteLine("Object deserialized successfully.");
                 deserializedPerson.Display();
             }
         }
     }
     

     Key Differences:

     • Uses [Serializable] attribute.

     • BinaryFormatter is used for serialization and deserialization.

     • FileStream handles writing and reading from a file.

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     Summary

     • Java: Uses Serializable interface and ObjectOutputStream/ObjectInputStream.

     • Python: Uses pickle.dump() and pickle.load().

     • C#: Uses [Serializable] attribute and BinaryFormatter.

     Each language has different serialization approaches but achieves the same goal—converting objects into a storable/transmittable format and reconstructing them later.