Demystifying gRPC: Unleashing Lightning-Speed ​​Communication

Before we dive into the details of gRPC, it is important to clarify the relationship between various terms in the field of remote communications, which can be confusing at times.

RPC — Remote Procedure Call

According to Wikipedia, "In distributed computing, a remote procedure call (RPC) is when a computer program causes a procedure (subroutine) to be executed in a different address space, typically on another computer on a shared network, just as if it were a normal (local) procedure call, without the programmer explicitly coding the details of the remote interaction."

In short, it is a way for one computer program to request another program to perform a certain task, even if they are located on different computers. It is a bit like calling a function in your program, although it is executed on a different machine. It is a procedure call that acts as if it is on the same machine, but it is not actually on the same machine. The RPC library/framework is responsible for abstracting all these complexities.

RPC Process

The RPC framework is responsible for shielding the underlying transmission method (TCP or UDP), serialization method (XML/JSON/binary) and communication details. Service callers can call remote service providers just like calling local interfaces without having to worry about the underlying communication. This involves the details and process of the call.

REST

REST stands for Representational State Transfer and is a mature architectural style for designing network applications. RESTful APIs use HTTP requests to perform CRUD (Create, Read, Update, Delete) operations, usually expressed as URLs. REST APIs are known for their simplicity and use of standard HTTP methods such as GET, POST, PUT, and DELETE.

HTTP

HTTP (Hypertext Transfer Protocol) is the basis for data communication on the Internet. It defines the format and transmission of messages, as well as how web servers and browsers respond to various commands. HTTP has evolved over time, and different versions have provided various features and improvements:

• HTTP/1.0: The first version of HTTP was very simple and lacked many modern features. In HTTP/1.0, each request required a new TCP connection, resulting in inefficiency.
• HTTP/1.1: HTTP/1.1 improves HTTP/1.0 by introducing a mechanism to keep active connections, allowing multiple requests and responses to be sent over a single TCP connection, thus reducing latency. However, it still has some limitations, such as the "head of blockage" problem, where a slow request can block subsequent requests in the same connection, resulting in a "waterfall" effect.
• HTTP/2: HTTP/2 introduces a binary frame mechanism that allows multiplexing, request prioritization, and header compression. These enhancements significantly improve the efficiency and speed of network communications. It eliminates the "head blocking" problem by allowing multiple concurrent streams within a single connection.
• HTTP/3: The latest version, HTTP/3, further improves performance by using the QUIC transport protocol. It focuses on reducing latency, especially in the presence of high packet loss or unreliable networks. HTTP/3 is designed to be more resilient and efficient than its predecessor.

So now we understand the terminology. Let’s get started!

What is gRPC?

gRPC (what does the “g” stand for here?) is an inter-process communication technology that allows you to connect, call, operate, and debug distributed heterogeneous applications as easily as making a local function call.

When you develop a gRPC application, the first thing you need to do is define a service interface. The service interface definition contains information about how to consume the service, which remote methods the consumer is allowed to call, what method parameters and message formats to use when calling these methods, and so on. The language we specify in the service definition is called the interface definition language (IDL).

gRPC uses protocol buffers as the IDL for defining service interfaces. Protocol buffers are a language-independent, platform-neutral, and extensible mechanism for serializing structured data.

gRPC Architecture

What makes gRPC lightning fast? Here’s what’s going on under the hood:

HTTP/2: In 2015, HTTP/2 replaced HTTP/1.1 and provided a multiplexing feature, allowing multiple requests and responses to share a single connection, improving efficiency.

• Request/response multiplexing: Thanks to HTTP/2’s binary frames, gRPC can handle multiple requests and responses within a single connection, revolutionizing communication efficiency.
• Header compression: HTTP/2's HPack strategy compresses headers, reducing payload size. Combined with gRPC's efficient encoding, this makes performance excellent.

Protobuf: The Secret Weapon

One of the key factors in the gRPC efficiency game is protocol buffers, or Protobuf for short. Protobuf defines data structures and function contracts. Both the client and the server need to use the same Protobuf language, which is how they understand each other. Protocol buffers (ProtoBuf) play three main roles within the gRPC framework: defining data structures, specifying service interfaces, and enhancing transmission efficiency through serialization and deserialization.

What are the advantages of gRPC

In addition to having a very cute mascot, the reason for adopting gRPC lies in its unique advantages:

• Efficiency of inter-process communication: Unlike JSON or XML, gRPC uses a binary protocol based on protocol buffers for communication, which improves speed. It is built on HTTP/2, making it one of the most efficient inter-process communication technologies.
• Clearly defined service interfaces and patterns: gRPC encourages contract definition first, prioritizing service interface definition rather than delving into implementation details. This simplicity, consistency, reliability, and extensibility define the application development experience.
• Strong typing and multi-language support: gRPC uses protocol buffers to define services, clearly specifying the data types communicated between applications. This helps improve stability and reduce runtime and interoperability errors. In addition, gRPC can be seamlessly integrated with a variety of programming languages, giving developers the flexibility to choose their preferred language.
• Bidirectional streaming and built-in features: gRPC natively supports streaming on both the client and server sides, simplifying the development of streaming services and clients. It also has built-in support for key features such as authentication, encryption, resilience (including deadlines and timeouts), metadata exchange, compression, load balancing, and service discovery.
• Cloud Native Integration and Maturity: As part of the Cloud Native Computing Foundation (CNCF), gRPC integrates seamlessly with modern frameworks and technologies, making it a preferred choice for communication. Projects in CNCF, such as Envoy, support gRPC, and many monitoring tools, including Prometheus, work effectively with gRPC applications. In addition, gRPC has been extensively tested at Google and is widely adopted.