Message serialization in Spring Boot - Performance & Optimization

Performance: Message serialization

MEDIUM IMPACT

Message serialization affects the speed of data transfer between services and the time to process messages in the application.

Sending data between microservices

Spring Boot

public record User(String name, int age) {}

// Using JSON with Jackson
ObjectMapper mapper = new ObjectMapper();
String json = mapper.writeValueAsString(user);
outputStream.write(json.getBytes(StandardCharsets.UTF_8));

JSON serialization is faster and produces smaller messages, improving network and CPU efficiency.

📈 Performance Gainreduces message size by 70%, processing time under 20ms

Sending data between microservices

Spring Boot

public class User {
  private String name;
  private int age;
  // getters and setters
}

// Using default Java serialization
ObjectOutputStream out = new ObjectOutputStream(socket.getOutputStream());
out.writeObject(user);

Default Java serialization is slow and produces large message sizes, increasing network latency and CPU usage.

📉 Performance Costadds 50-100kb per message, blocks processing for 50-100ms

Performance Comparison

Pattern	CPU Cost	Message Size	Network Impact	Verdict
Default Java Serialization	High	Large (~50-100kb)	High latency and bandwidth use	[X] Bad
XML Serialization	Medium	Very Large	High latency and bandwidth use	[!] OK
JSON Serialization	Low	Medium	Efficient network use	[OK] Good
Binary Serialization (Protobuf)	Very Low	Small	Minimal latency and bandwidth	[OK] Good

Rendering Pipeline

Message serialization impacts the server processing stage before sending data over the network. Efficient serialization reduces CPU time and network payload size, speeding up data delivery.

→Server Processing

→Network Transfer

→Client Processing

⚠️ BottleneckServer Processing (serialization CPU cost)

Optimization Tips

1Avoid default Java serialization for network messages due to size and speed issues.

2Prefer JSON or binary formats like Protobuf for faster serialization and smaller messages.

3Set explicit content types in APIs to ensure efficient serialization formats are used.

Performance Quiz - 3 Questions

Which serialization format generally produces the smallest message size?

A Binary formats like Protobuf

B XML

C Default Java serialization

D Plain text

DevTools: Network

How to check: Open DevTools, go to Network tab, inspect the size and timing of API responses or messages.

What to look for: Look for large payload sizes and long transfer times indicating inefficient serialization.

Practice

1. What is the main purpose of message serialization in Spring Boot?

easy

A. To handle user authentication and authorization

B. To compile Java code into bytecode

C. To convert objects into a format like JSON for easy data sharing

D. To manage database connections automatically

Solution

1. Step 1: Understand serialization concept

   Serialization means converting an object into a format that can be sent or stored, like JSON.

2. Step 2: Relate to Spring Boot usage

   Spring Boot uses serialization to send Java objects as JSON in REST APIs.

3. Final Answer:

   To convert objects into a format like JSON for easy data sharing -> Option C

4. Quick Check:

   Serialization = Convert objects to JSON [OK]

Hint: Serialization means turning objects into JSON or similar formats [OK]

Common Mistakes:

• Confusing serialization with compiling code
• Thinking serialization manages databases
• Mixing serialization with security features

2. Which of the following is the correct way to ensure a Java class is serializable by Spring Boot's default JSON serializer?

easy

A. Use @Entity annotation on the class

B. Make the class implement Serializable interface

C. Mark all fields as transient

D. Add public getters for all fields and a no-argument constructor

Solution

1. Step 1: Identify Spring Boot serialization requirements

   Spring Boot uses Jackson which requires public getters and a no-argument constructor to serialize objects properly.

2. Step 2: Evaluate options

   Implementing Serializable is not required for JSON serialization. Marking fields transient prevents serialization. @Entity is for database mapping, not serialization.

3. Final Answer:

   Add public getters for all fields and a no-argument constructor -> Option D

4. Quick Check:

   Getters + no-arg constructor = JSON serialization [OK]

Hint: Public getters and no-arg constructor enable JSON serialization [OK]

Common Mistakes:

• Thinking Serializable interface is needed for JSON
• Marking fields transient disables serialization
• Confusing @Entity with serialization setup

3. Given the following Spring Boot controller method, what will be the JSON output when accessing /user?

public record User(String name, int age) {}

@GetMapping("/user")
public User getUser() {
    return new User("Alice", 30);
}

medium

A. ["Alice",30]

B. {"name":"Alice","age":30}

C. {"User":{"name":"Alice","age":30}}

D. Error: Records cannot be serialized

Solution

1. Step 1: Understand record serialization in Spring Boot

   Spring Boot with Jackson supports Java records and serializes them as JSON objects with field names.

2. Step 2: Predict output for User record

   The record fields 'name' and 'age' become JSON keys with their values.

3. Final Answer:

   {"name":"Alice","age":30} -> Option B

4. Quick Check:

   Records serialize as JSON objects with fields [OK]

Hint: Java records serialize as JSON objects with field names [OK]

Common Mistakes:

• Expecting JSON array instead of object
• Thinking records cause serialization errors
• Assuming nested JSON with class name

4. Consider this Spring Boot REST controller snippet:

@GetMapping("/product")
public Product getProduct() {
    return new Product("Book", null);
}

public class Product {
    private String name;
    private String description;

    public Product(String name, String description) {
        this.name = name;
        this.description = description;
    }

    public String getName() { return name; }
    // Missing getter for description
}

What issue will occur when this endpoint is called?

medium

A. The JSON will include only the name field; description is missing

B. The JSON will include both name and description fields

C. A runtime error occurs due to missing getter

D. The endpoint will not compile

Solution

1. Step 1: Check serialization requirements

   Jackson serializes fields using public getters. Missing getter means that field is ignored in JSON output.

2. Step 2: Analyze given code

   Product class lacks getter for 'description', so JSON will only show 'name'. No runtime error or compile error occurs.

3. Final Answer:

   The JSON will include only the name field; description is missing -> Option A

4. Quick Check:

   Missing getter = field omitted in JSON [OK]

Hint: Missing getter means field won't appear in JSON output [OK]

Common Mistakes:

• Expecting runtime or compile error
• Assuming all fields serialize without getters
• Thinking null values cause errors

5. You want to customize JSON serialization in Spring Boot to exclude fields with null values from the output. Which approach is correct?

hard

A. Configure Jackson's ObjectMapper to set SerializationInclusion to NON_NULL

B. Mark all nullable fields as transient

C. Remove getters for nullable fields

D. Use @JsonIgnore on all fields

Solution

1. Step 1: Understand how to exclude null fields in JSON

   Jackson allows configuration to exclude null fields by setting SerializationInclusion to NON_NULL.

2. Step 2: Evaluate options

   Marking fields transient or removing getters prevents serialization entirely, not just null exclusion. @JsonIgnore excludes fields always.

3. Final Answer:

   Configure Jackson's ObjectMapper to set SerializationInclusion to NON_NULL -> Option A

4. Quick Check:

   Set SerializationInclusion = NON_NULL to skip nulls [OK]

Hint: Set ObjectMapper to exclude nulls with NON_NULL inclusion [OK]

Common Mistakes:

• Using transient to exclude nulls (excludes always)
• Removing getters breaks serialization
• Using @JsonIgnore excludes fields always