Do you want to know if gRPC is the way of the future? The goal of this essay is to describe the differences between two architectural API styles: REST and gRPC. Before we get into their differences, let’s define an API and why it’s so important for microservices systems. 

After that, we’ll go through how RPC is the foundation for gRPC and look at the key differences between gRPC and REST APIs. After comparing the two, we’ll determine when to use one architectural style over the other.

What an API is and what it does? 

Application Programming Interfaces, or APIs, are a type of programming interface. These interfaces work as a software middleman, establishing precise rules and determinations for programmes to interact and communicate with one another. An API is in charge of delivering a user’s response to a system, which is then returned to the user by the system. Is it still a little perplexing?

An API defines the types of queries that one application (web page or mobile app) can make to another, as well as how those requests should be made, the data formats that should be used, and the best practices that users should follow. 

Because they are the two most prevalent architectural methods for constructing APIs, this article compares gRPC (Google Remote Procedure Call) and REST (Representational State Transfer).

What exactly is gRPC? 

The acronym gRPC stands for Google Remote Procedure Call, and it is an RPC-based variation. This technology is based on an HTTP 2.0 RPC API implementation, but HTTP is not presented to the API developer or the server. As a result, there’s no need to worry about how RPC principles are mapped to HTTP, which simplifies things.

Overall, the goal of gRPC is to speed up data transmission between microservices. It is based on the concept of selecting a service, then establishing methods and parameters to allow for remote calling and return types. 

It also describes the RPC API paradigm in an IDL (interface description language), which makes determining remote operations easier. Protocol Buffers are used by default in the IDL to describe the service interface as well as the structure of payload messages (although additional options are available).

REST vs. gRPC: a comparison 

Let’s look at the primary distinctions between gRPC and REST now that we’ve covered the basics. 

HTTP 1.1 vs HTTP 2 

REST APIs use a request-response communication model, which is typically based on HTTP 1.1. Unfortunately, if a microservice receives many requests from multiple clients, the model must handle each request individually, which slows down the entire system. REST APIs can, however, be developed on HTTP 2, but the request-response communication architecture stays the same, preventing REST APIs from taking advantage of HTTP 2 features like streaming communication and bidirectional support.

gRPC does not have the same problem. It’s based on HTTP 2 and uses a client-response communication architecture instead. Due to gRPC’s capacity to receive many requests from multiple clients and handle those requests simultaneously by constantly streaming information, these conditions permit bidirectional communication and streaming communication. Furthermore, gRPC can support “unary” interactions, such as those built on HTTP 1.1.

To summarise, gRPC can handle unary interactions as well as other types of streaming: 

• Unary: When a client sends a single request and receives a single response, it is said to be unary. 
• Server-streaming: When a server answers to a client’s request with a stream of messages, this is known as server-streaming. When all of the data has been transmitted, the server sends a status message to conclude the operation.
• Client-streaming: It occurs when a client sends a series of messages and the server responds with a single message. 
• Bidirectional streaming: The two streams (client and server) are independent of one another, allowing them to send messages in any order. The bidirectional streaming is started and stopped by the client.

Browser Compatibility 

This is likely one of the most significant REST API advantages over gRPC. On the one hand, all browsers fully support REST. When it comes to browser support, however, gRPC is still rather limited. Conversions between HTTP 1.1 and HTTP 2 are unfortunately only possible with gRPC-web and a proxy layer. As a result, gRPC is mostly utilised for internal/private systems (API programmes that access backend data and application functionality within a certain business).

Data Structure of the Payload 

As previously stated, gRPC serialises payload data using Protocol Buffer by default. This method is lighter since it allows for a highly compressed format, which minimises the size of the messages. Additionally, because Protobuf (or Protocol Buffer) is binary, it serialises and deserializes structured data to communicate and send it. In other words, Protobuf communications can be automatically transformed to the programming languages of the client and server. 

REST, on the other hand, sends and receives data mostly in JSON or XML formats. JSON is the most common format because of its flexibility and ability to communicate dynamic data without having to adhere to a tight structure, despite the fact that it does not require any. Another key advantage of JSON is its human-readable level, which Protobuf currently lacks.

Features of Code Generation 

REST API, unlike gRPC, does not have built-in code generation capabilities, therefore developers must use a third-party tool like Swagger or Postman to generate code for API calls. 

gRPC, on the other hand, includes native code generating facilities thanks to its protoc compiler, which works with a variety of programming languages. This is especially useful for microservices systems that combine services written in a variety of languages and platforms. Overall, the SDK creation is made easier by the built-in code generator (Software Development Kit).

Conclusion 

There are numerous benefits to using gRPC. It can make the most of HTTP 2 by leveraging multiplexed streams and adhering to the binary protocol, unlike REST. Furthermore, the Protobuf message structure improves efficiency, and don’t forget about the built-in code generating tools that enable a multilingual environment. gRPC is a promising API architectural approach for these reasons. 

Despite this, the lack of browser support makes competing with REST universal support difficult. REST remains the most popular microservices solution and the glue that holds them together. As a result, it’s very likely that it’ll last a long time, and it’s a really well-developed and successful architecture.