Protocol Buffers (Protobuf)

Language: Java

Serialization / Messaging

Protobuf was developed by Google to provide a faster and smaller alternative to XML and JSON for serializing structured data. It supports backward and forward compatibility, strong typing, and works across multiple languages. Protobuf is widely used in RPC systems, microservices, data storage, and messaging applications.

Protocol Buffers (Protobuf) is a language-neutral, platform-neutral, and extensible mechanism for serializing structured data. It is used to efficiently encode data for communication between services, storage, or configuration in Java applications.

Installation

maven:

Add dependency in pom.xml:
<dependency>
  <groupId>com.google.protobuf</groupId>
  <artifactId>protobuf-java</artifactId>
  <version>3.24.3</version>
</dependency>

gradle: implementation 'com.google.protobuf:protobuf-java:3.24.3'

Usage

Protobuf allows you to define structured data in `.proto` files, generate Java classes, and serialize/deserialize data efficiently. It supports messages, enums, nested structures, and repeated fields.

Defining a message in a .proto file

syntax = "proto3";

message Person {
  string name = 1;
  int32 id = 2;
  string email = 3;
}

Defines a simple `Person` message with `name`, `id`, and `email` fields.

Generating Java classes

# Using protoc compiler
protoc --java_out=src/main/java person.proto

Generates Java classes from the .proto definition for use in your application.

Serializing a message

Person person = Person.newBuilder()
    .setName("Alice")
    .setId(1)
    .setEmail("alice@example.com")
    .build();

byte[] data = person.toByteArray();

Builds a Protobuf message and serializes it to a byte array for storage or transmission.

Deserializing a message

Person parsedPerson = Person.parseFrom(data);
System.out.println(parsedPerson.getName());

Parses a byte array back into a Protobuf message instance.

Using nested messages and enums

message AddressBook {
  repeated Person people = 1;
}

AddressBook book = AddressBook.newBuilder()
    .addPeople(person)
    .build();

Shows how to define repeated (list) fields and nested messages in Protobuf.

Working with optional and default values

Person person = Person.newBuilder()
    .setName("Bob")
    .build();
System.out.println(person.getEmail()); // empty string as default

Optional fields take default values if not explicitly set.

Error Handling

InvalidProtocolBufferException: Occurs when parsing corrupted or incompatible byte arrays. Ensure the data matches the message schema.

Missing required fields: Ensure all required fields are set before serialization (for proto2 syntax) or rely on default values (proto3).

Best Practices

Use `.proto` version 3 syntax for simplicity and modern features.

Leverage repeated fields instead of lists for efficient storage.

Keep backward and forward compatibility by assigning unique field numbers.

Avoid removing fields; deprecate them instead to maintain compatibility.

Use Protobuf for inter-service communication, storage, or network efficiency.

Official Docs Github