The Battle of APIs: gRPC vs REST Explained

If you are a developer, you know you can design your API in two ways, but when it comes to gRPC vs REST, which one should you choose?

An API is a mechanism or interface through which two separate software components can communicate or talk to each other based on agreed-upon definitions and protocols.

In gRPC, one component, a client, calls or invokes specified functions in another software component called the server.

For REST, the concept is the same, except the client requests or updates data on the server instead of calling functions. These two are the most commonly used APIs.

Here are a few REST vs gRPC comparisons:

» Protocol: It uses HTTP/2 for transport, whereas REST normally uses HTTP/1.1.

» Data format: It uses protocol buffers for serialization, while REST usually relies on JSON or XML.

» Design API: gRPC is based on the Remote Procedure Call paradigm, whereas REST is based on the architectural constraint of the Representational State Transfer model.

» Streaming: gRPC supports bi-directional streaming, whereas REST only supports request-response patterns.

In this article, we'll compare gRPC vs REST API to help you choose the best protocol for your project.

What Is gRPC?

I am starting the gRPC vs REST battle by understanding that gRPC is a high-performance, open-source universal framework like Flutter vs React Native for distributed systems via Remote Procedure Calls (RPC).

It is from Google and is supposed to be fast, efficient, and highly scalable. Built using the HTTP/2 protocol on top, it uses protocol buffers by default as its data format.

Protocol buffers are a binary serialization format that is also language agnostic. One major advantage of gRPC is that one can define the interface for the APIs using protocol buffers.

It allows you to define the message types, services, and methods for your APIs in a language-agnostic way, and the gRPC tooling will automatically generate client and server code in a language of your choice.

In the battle of gRPC vs HTTP, the two differ because HTTP APIs function on the HTTP 1.1 and gRPC functions on the HTTP 2.0 model.

gRPC supports many programming languages, such as Python vs Java, C#, Go, and more. It also has advanced features, including bidirectional streaming, flow control, and load balancing.

Hence, gRPC is also suitable for building high-performance, low-latency, and scalable microservices.

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Key Features of gRPC

Here are some key features of the gRPC services in the comparison of gRPC vs REST:

1. Helping Protocol Buffers

Protocol buffers (Protobuf) are the cogs that drive gRPC. This tool, developed by Google, deals with data arrangement, employing binary serialization to let data structures assume unique formats.

Protobuf augments the possibilities of code creation in numerous languages to read and write organized data across various data channels.

Example:

2. Highly Functional Efficiency

Google's gRPC has been designed to function properly even in heavy traffic situations.

It exploits the HTTP/2 building blocks to split requests and responses over a dedicated TCP connection, allowing concurrent messaging or streams and server-driven approaches.

3. Streaming Capacities

gRPC supports the bidirectional streaming feature with which the server and the client can intercommunicate without any constraints related to the order of messages as long as they are required.

This is very useful for software, which thrives on real-time data; the client can take advantage of live updates from the server.

4. Built-in Resilience with Load Balancing, Tracing, Health Checks, and Security

In the gRPC vs REST comparison, gRPC's inherent malleability should be appreciated.

With it, one gets ready-to-use solutions for customizing features like load balancing, distributed tracing, health checks, and security mechanisms.

Besides all this, it also facilitates several security strategies, like the token-based access that follows Google's API development.

5. Compatibility with Multiple Programming Language

gRPC applications can be developed in many different languages, including but not limited to C++, Java, Python, Go, Ruby, Next Js vs React, etc.

Cross-language capabilities allow, for example, a Java-established gRPC server to respond aptly to requests from clients running with a Python-based gRPC application for frictionless communication.

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What is the REST API?

Now, to the next counterpart of the gRPC vs REST API debate, the application interface (API) of Representational State Transfer (REST) is an architectural concept that describes how to structure the web's services.

In short, REST is a methodology for designing web services that employ HTTP as its primary system with standard HTTP verbs of action.

You can use GET, POST, PUT, and DELETE when making CRUD operations for every available resource.

REST has been the most accepted web application architecture for creating widely adopted, easy-to-use APIs.

REST supports various data formats, such as JSON, XML, etc. Therefore, REST APIs are an extremely versatile option for creating APIs that need to be consumed by a wide range of clients.

Key Features of REST API

Here are some of the features of REST APIs to contribute to the gRPC vs REST comparison:

1. Stateless Functionality

One of the quite fundamental characteristics of REST APIs lies in the concept of "stateless" operations.

The term stateless implies that there is nothing in the form of preserved information, or "state," between two consecutive engagements with software during the system development life cycle.

With no state at all, the resilience-plus flexibility of the API is enhanced to support different processes for every request.

2. Client and Server Dual Functionality

REST APIs work on a client-server architecture. The client-end focuses on UI/UX design trends or data representation.

On the other hand, the server end takes care of request processing, function execution, and resource management.

This division has the benefit of improving and growing independently on both the client-end and server-end sides.

3. Caching

Cacheability is another fundamental property of RESTful APIs. Responses by the servers can be cached locally by clients, so the procedures are fastened.

The server should then mark response instances as cacheable and those that are not to prevent the reapplication of the same nonsensical data on interactions between the stack for the client and server.

4. Component Composition Hierarchy

In the case of a REST API, there is an appropriate hierarchy in which each element has a definite role.

Such a composition is flexible because one-level alterations should not affect the rest of the framework.

In addition, the hierarchical composition also increases the API's cyber security since transactions between elements are strictly limited to immediate adjacent layers.

5. Uniform Interface

REST APIs retain the characteristic of a uniform interface, separating the client and server parts to evolve.

It includes a UI/UX designer roadmap that encapsulates four guiding principles:

» Resource-Centric

» Interaction through Responses

» Transparent Messaging

» Dynamically Managing App State with Hypermedia (HATEOAS)

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gRPC vs REST API: The Similarities

After understanding the meaning of both the API architecture in the gRPC vs REST comparison, these two share some innate similarities as API architectural approaches as well, including:

Data Exchange Mechanism

Allow two software components, the client and the server, to communicate and exchange data under a shared set of rules. These rules apply regardless of how each component may operate internally.

Communication Based on HTTP

Both pass data via the HTTP request-response mechanism, which the web prefers for efficient communication. However, in gRPC, this is not apparent to the developer, whereas it's somewhat more evident in REST.

Flexibility in Implementation

You can implement REST and gRPC in many programming languages, making them highly portable across cloud development environments. This leads to optimal interoperability with near-universal support.

Suitability for Scalable, Distributed Systems

gRPC vs REST use the following:

» Asynchronous communication is needed so the client and server can communicate without disturbing operations.

» Stateless design so the server does not need to remember the client state.

Architecture Difference: gRPC vs REST

Even though REST and gRPC provide a similar function, the underlying models differ drastically in architecture:

1. Communication Model

A client makes one REST API request to a server using a REST API, and the server sends back one response.

The client must wait for the server's response before performing operations.

It is a request-response model with a one-to-one data connection; it’s as advantageous as a data warehouse.

In contrast, in gRPC, a client sends one or more requests that may return one or more responses from the server.

Data streams can be unary, which is one-to-one; one-to-many server streaming; client streaming, which is many-to-one; or bidirectional streaming, which is many-to-many.

It's a client-response interaction model and is possible because gRPC is based on HTTP 2. This is the main architectural comparison of gRPC vs REST.

2. Callable Operations on the Server

In a gRPC API, callable server operations are defined by services; they can also be called functions or procedures.

A gRPC client calls the functions in the same manner that an application calls the function internally. This design is termed service-oriented. Here is an example of how to do this:

createNewOrder(customer_id, item_id, item_quantity) -> order_id

In REST, the client uses a limited number of HTTP request verbs on server resources defined by a URL. The client calls the resource itself.

This is an entity-oriented design. The entity-oriented design goes well with object-oriented programming methods. Here is an example:

POST /orders <headers> (customer_id, item_id, item_quantity) -> order_id

While you can design gRPC APIs in an entity-oriented approach, this is not a constraint of the system itself; this is the operational difference of gRPC vs REST.

3. Data Exchange Format

In a REST API, data structures passed between software development components are usually expressed in JSON data exchange format. Other data formats, such as XML and HTML, can be passed.

JSON is readable but needs to be serialized and translated into a programming language because it is flexible.

On the other hand, gRPC uses the default Protocol Buffers format but also natively supports JSON.

The server then defines this data structure using the protocol buffer and interface description language (IDL) in a proto-specification file.

gRPC then serializes the structure to a binary format and deserializes it into any specified programming language for app development.

This mechanism makes it faster than using JSON, which does not get compressed while transmitted. Protocol Buffers are not human-readable, as they would be in a REST API utilized by JSON.

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Coding Differences: gRPC vs REST API

Here are the coding examples in the gRPC vs REST battle:

gRPC

Here is an example of implementing a gRPC server and client in Python:

Here, we decide on a calculator service with one method, add, which sums two integers. We'll use protocol buffers to define the service's data types.

You will also need the Protocol Buffers compiler (protocol) and the Kotlin gRPC plugin to execute service and client code generation.

REST API

Here’s an example of a REST API implementation in Python using the Flask framework:

In this example, we define a CalculatorController class that handles requests to the add endpoint using a POST method.

The controller's add function accepts a CalculatorRequest object containing two integer values and returns a CalculatorResponse object containing the sum of the two values.

Notice that this implementation uses JSON to serialize data instead of protocol buffers.

That's a very simple example, but it demonstrates how easy it is to implement a REST API.

The annotation Request Body tells Spring to deserialize the request's JSON body into a CalculatorRequest object while the response is automatically serialized back to JSON.

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Other Essential Distinctions: gRPC vs REST

Other than the architectural style, REST API vs gRPC have other intrinsic differences.

1. Client-Server Combination: REST vs gRPC

REST is loosely coupled, which implies that the client or server does not need to know about the implementation of the other. Because of this loose coupling, the API can evolve more efficiently.

While gRPC is strongly bound. That means the client and the server should have access to the same proto file, and an update on the file necessitates an update on the server and the client.

2. Code Generation: gRPC vs REST

gRPC has built-in selections of native client-side and server-side code generation features. They are available in multiple backend languages because of the Protocol Buffer compiler.

On the other hand, REST does not have a built-in code generation mechanism. So, if developers want this feature, they must use third-party tools.

3. Bidirectional Streaming: gRPC vs REST

gRPC provides bidirectional streaming communication.

This means the client and the server can send and receive multiple requests and responses simultaneously over a single connection.

REST doesn’t have this feature.

Summary of Differences: gRPC vs REST

Here is the summary of REST vs gRPC:

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When Should You Use REST API vs gRPC?

With two options to choose from, which API should you use?

That depends on the project you're working on, for instance, mobile app development using Python and what you need the API to do for such a project.

REST is still the most common, but that doesn't mean it should automatically be used.

Here is the appropriate usage of gRPC vs REST:

A. When Should You Use REST APIs?

When should you use REST APIs? They are most commonly used in building infrastructures based on microservices.

REST is the most common choice whenever you plan to develop a game app, for instance, or a more complex computer system like cloud ERP systems that demand connecting microservices.

Systems that require speed also need to be executed via REST APIs. If you need standardized HTTP protocol, high-speed iteration, and multi-language microservices connectivity, REST is your number one choice.

It also supports universal use with third-party tools, making it perfect for apps and web services.

B. When Should You Use gRPC?

Most third-party tools have native features that haven't been developed to support compatibility.

They are more used to build internal systems, which means infrastructures are not open to any outside user of an organization; an excellent example of this would be cloud computing or edge computing.

Considering this, gRPC APIs can be of usage when the following circumstances occur:

» Microservices connections: gRPC's latency is very low, and it communicates at a very high throughput, which makes it particularly useful for architectures of lightweight microservices.

» Multilingual systems: gRPC is a perfect fit for handling multiple-language environments due to the native code generation support it provides to a wide variety of development languages.

» Real-time streaming: If you need real-time communication, gRPC enables the management of bidirectional streaming so that your system can send and receive messages without waiting for unnecessary client response communications.

» Low-power, low-bandwidth networks: gRPC's serialized Protobuf messages offer lightweight messaging with better efficiency and performance than JSON, which is used mainly in the Internet of Things (IoT) in low-power networks with bandwidth constraints.

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What Are Microservices-Based Applications?

Microservices-based applications overcome the most significant disadvantages that traditional, monolithic applications provide.

This essentially means a single codebase that is indivisible for hosting the programming of every feature and service in its very monolithic application and contains all types of management.

Every type of servicing will be managed in it through services and features. Many companies take their initiation in a monolithic application because it is typically the easiest.

In the gRPC vs REST battle, microservice is a method used in solution architecture that answers the difficulty it will bring when everything else starts connecting.

The components are microservices. Microservices use APIs to talk to other independent microservices. This way, a more extensive application architecture lies within an API-connected collective group of microservices.

APIs enable the connection of autonomously running microservices, enabling a pluggable, component-based system.

They can work together even if the microservices are designed and coded in another programming language or platform.

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What Does REST Have Over gRPC in the gRPC vs REST Comparison?

What could be the excellent reason REST enjoys its popularity? If you want to learn how REST and gRPC may differ, here are some things you should know before jumping into those differences.

APIs, short for application programming interfaces, are rules and definitions that allow applications to communicate.

APIs are compatible by nature. They establish the connectivity needed between microservices.

Even though microservices can be written in different programming languages, they are compatible with cross-platform app development frameworks.

An API defines the types of calls and requests an application may make to another, the way to make such a request, the data formats one should apply, and the conventions one must follow.

So, APIs allow more applications within larger systems by linking multiple functionalities. You add more functions or microservices so the functions work, interact with other functions, etc.

Conclusion

To conclude the gRPC vs REST debate, REST is good if you need a flexible API to handle a wide range of data formats and various communication styles.

But remember that REST doesn't work great for any task.

It shines for application functions requiring performance, especially low latency, and supports streaming or other bidirectional modes.

This framework also builds good microservices. Services will then break down into smaller services where smaller services can communicate better.

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Frequently Asked Question

Q. Is gRPC better than REST?

Ans: gRPC, unlike REST, was built specifically to allow developers to create high-performance APIs for microservice architectures across distributed data centers. It is well-suited for internal systems that require real-time streaming and large data loads.

Q. Is gRPC always faster than REST?

Ans: You must call the server address where gRPC requires the client to set it up. The payload is relatively small, and multiple clients call the server simultaneously, so REST API remains relevant today. Therefore, gRPC is much quicker than the REST API in all such scenarios.

Q. Why is gRPC not widely used?

Ans: gRPC is a high-performance RPC framework but has not been widely adopted for several reasons. First, it's rather complicated to set up and use, which can be a massive barrier for developers who are not experienced in microservices architecture.

Q. Is gRPC a replacement for REST?

Ans: gRPC and REST are two communication protocols used to build an API. Although gRPC is an excellent candidate to replace REST in specific contexts, it is not a complete replacement.