Written by Dženis Imamović, Software Developer Softray Solutions
In today’s world of distributed systems and rapid deployments, choosing the right communication protocol for your backend architecture is a big decision.
Microservice architecture is a software implementation methodology where an application is composed of various small, individual, independently deployable services that perform one unit of a particular business function. In a microservices architecture, each service has its process and communicates with the other services through a well-defined API built on top of a network. But this massively popular architecture always brings a well-known problem – communication between/among the services. In this context, REST and gRPC are two architectural styles in API design.
REST has been the backbone of web APIs for years, popular for its simplicity and flexibility. But as backend architectures evolve, newer options like gRPC have gained traction for their performance and efficiency in handling complex microservices communication.
So, is it time to rethink REST? For most use cases, gRPC offers a performance boost, but REST’s readability and compatibility still make it a reliable workhorse.
Understanding their key differences goes beyond just choosing one over the other – it’s about identifying what each protocol brings to the table and how it aligns with our specific application needs.
REST (Representational State Transfer)
REST is a protocol that follows a resource-based architecture with HTTP verbs (GET, POST, etc), and is uniquely identified by its URI. Common resource representations include JSON and XML, among others. Interaction with resources is done using these representations via standard HTTP methods.
Most modern REST APIs follow request-response models of communication.
REST has many strengths that have contributed to its popularity, including:
Platform Independence: REST works over HTTP, which is supported by virtually all devices and languages.
Readability with JSON: REST APIs commonly use JSON as the data format, which is both human-readable and easy to parse. JSON is widely supported, enabling interoperability between diverse systems.
Browser Support: Works directly in browsers, making it ideal for client-facing APIs.
Error Handling: This relies on standard HTTP status codes for handling errors, which is straightforward and well-documented.
gRPC (gRPC Remote Procedure Calls)
The concept of RPC dates back to the early days of distributed computing. RPC APIs allow developers to call remote functions in external servers as if they were local to their software. RPC has gained popularity nowadays with protocols like gRPC, which combines HTTP/2 and Protocol Buffers to deliver highly efficient remote calls.
gRPC is a modern, open-source RPC framework developed by Google, which enables direct function calls across network services, abstracting the lower-level details of network communication.
There’s no standard like URIs in REST. Instead, the method name and its signature become the defining aspect. While this can be seen as flexible, it can also lead to challenges with versioning and changing method signatures over time.
gRPC offers a different set of advantages that are particularly suited to high-throughput microservices environments:
Binary Data Format (Protocol Buffers): instead of JSON or other text-based formats, gRPC messages are serialized using Protobuf, an efficient binary message format, which is smaller, faster to serialize, and less error-prone.
HTTP/2 based: gRPC is based on HTTP/2, which provides significant performance benefits over HTTP/1.1, and features like multiplexing and header compression, making it faster and more efficient than REST.
Streaming: Supports client, server, and bidirectional streaming by default, useful for real-time applications.
Built-in Code Generation: With gRPC, the server defines service definitions that clients can automatically generate code for. This simplifies client-server communication by removing much of the manual work.
Method-oriented; allows defining RPC methods rather than accessing resources through HTTP endpoints. Due to these features, gRPC is often chosen for internal microservices communication, especially in performance-critical applications, or services with heavy data transfer.
Error Handling: Offers rich error handling through gRPC status codes, which provide more granular feedback compared to HTTP codes. GRPC is also strongly typed and catches errors on compile time.
The main downside for gRPC is adoption, and that adoption is due to the complexity of designing and building a gRPC API. While RESTful libraries and communication types like JSON are natively supported in browsers, gRPC requires third-party libraries such as gRPC-web, as well as a proxy layer, to perform conversions between HTTP 1.1 and HTTP 2.0.
However, in a backend-to-backend communication, or in a microservices architecture, gRPC APIs offer unparalleled speed and performance. gRPC APIs can be sometimes 5 to 10 times faster when sending or receiving data, especially when streaming data.
Summary:
REST: A Long-standing Standard REST, with its resource-oriented structure, has been widely used for web APIs due to its simplicity and compatibility with HTTP. It leverages familiar HTTP methods (GET, POST, etc.), and human-readable formats like JSON, and provides broad support across platforms. REST’s readable, text-based messages and reliance on HTTP make it a solid choice for client-facing APIs and web-based applications.
gRPC: Modern, High-performance Communication gRPC is designed for high-performance, low-latency communication, especially in backend-to-backend scenarios. Using HTTP/2 and Protocol Buffers (a compact binary format), gRPC enables faster, more efficient data transmission, along with features like bidirectional streaming and built-in code generation for easier client-server interaction. gRPC’s efficiency and lower latency make it ideal for microservices communication in high-throughput environments.
While REST has been a reliable standard, gRPC is pushing the boundaries of what’s possible in high-performance applications. The two protocols offer distinct advantages and, in some cases, may even coexist within the same architecture to serve different parts of a system.