• Mislav Stipetic

Understanding the Basics of gRPC

gRPC is becoming a popular alternative for developers instead of REST (REpresentational State Transfer) in most projects. gRPC is a modern, high-performance framework developed by Google in 2015 to streamline messaging between clients and backend services. It can run in any environment, making it ideal for connecting services in every data center with pluggable support.

This article introduces you to gRPC as well as some information about protocol buffers. You'll learn the overview of gRPC and its significant momentum throughout the cloud-native community.

What is gRPC

gRPC is the latest iteration of RPC that uses HTTP/2 for transport and Protocol Buffers as the IDL. It can run across data centers and connect services using pluggable support for health checking and authentication. It's also ideal for load balancing and is also applicable in connecting devices and mobile applications directly to its backend services.

gRPC is also part of the Cloud Native Computing Foundation Ecosystem, which builds sustainable ecosystems and supports communities to improve further the health and growth of cloud-native open-source software. CNFC considers GRPC an incubating project, which means that end-users use it in production applications, and the project has a considerable number of contributors.

gRPC Service Defined Using Protocol Buffers

gRPC uses an open-source technology called Protocol Buffers, which provides a highly efficient serialization format for structured data. When working with protocol buffers, the first step that you need to take is to define the structure for the data that you want to serialize in a .proto file to identify the message type.

gRPC also provides protocol buffer compiler plugins that automatically produces server- and client-side code. Users refer to it as APIs on the client-side and execute the corresponding API on the server-side.

Once you've defined your data structure, you will then use the protocol buffer compiler to generate data classes based on your preferred language from your proto definition. So, if you chose C++ as your language, operating the compiler will create a class called "Person." You can use this class to automatically populate, retrieve, and serialize the "Person" protocol buffer message.

The gRPC programming API in most languages appears in both synchronous and asynchronous qualities. Users refer to synchronous remote procedure call as a blocking call. So, when a client requests the server, the client will wait until it receives a server's response. As with asynchronous RPC, the client makes an RPC call and waits for an acknowledgment from the server. Networks are inherently asynchronous and are useful when starting RPCs without blocking the current thread.

Introduction to gRPC core concepts

RPC (Remote Procedure Call) is a protocol that a program can use to send a service request from an application located on a different computer on a network without the need to learn about the network's detail. Like other RPC systems, gRPC also revolves around defining a service that users can access remotely with their parameters and return types. But what sets it apart from the current RPC frameworks?

The key difference lies with how gRPC uses protocol buffers. With gRPC, it utilizes protocol buffers to become the definition language for communication and serialization interface, which is different from JSON/XML. Protocol buffers can define the layout of data while generating the code from the same description. The system then uses the data to parse a flow of bytes representing the organized data.

How organizations can use gRPC to their advantage


gRPC uses Protobuf to serialize its messages. It's an efficient binary message format that serializes information on the server and client at a fast rate. Thus, resulting in a small message payload, which is crucial in downsizing bandwidth scenarios and other significant performance benefits over HTTP 1.x.

Code generation

Every gRPC formwork provides first-class support when it comes to generating codes. gRPC development's core file is the .proto file, which determines the contract of gRPC services as well as the messages. Whenever the system shares the .proto file between the server and the client, it simultaneously generates the message and client code. Client code generation prevents the duplication of messages between the client and the server. Thus, saving them time when developing applications and linking them with other services.

Stringent specification

The gRPC specification is strict when it comes to the format that a gRPC service needs to follow. By having stringent specification, it eliminates debate and helps developers save time because of its consistency across platforms as well as implementations.


gRPC service supports any streaming combinations, allowing it to provide the best support for streaming through HTTP/2. Although it's also compatible with HTTP 1.1, HTTP/2 has several advanced features that users will find helpful. Aside from a binary protocol for data transport, it also has built-in streaming that enables requests and responses to stream large data sets asynchronously.

Deadlines/ Timeouts and Cancellation

gRPC provides its clients with the ability to choose how long they're willing to wait for an RPC to complete. Once they've selected the deadline, it gets sent to the server directly, in which the server can decide alternative resolutions if ever the RPC exceeds the period.

Key Takeaways

gRPC is an excellent solution when you're dealing with use cases involving multilanguage communications with idiomatic APIs. It's also well suited for network constrained environments since it's always smaller compared to the JSON message. Polyglot environments can benefit from it, too, since gRPC tools support the most common development languages. But like everything else, it also has its weaknesses.

Since gRPC heavily relies on HTTP/2 features, it's impossible to call a gRPC service using a browser. Although there is gRPC-Web, which is an additional feature from the gRPC team, it only provides limited support in the browser.

The messages are also not readable for humans. Protobuf is highly efficient when it comes to sending and receiving gRPC messages. However, it's the binary format that isn't meant for humans. It requires the message's interface description in the .proto file to deserialize appropriately.

So, if you're planning to choose the right client application, it's always best to weigh its pros and cons. Learning more about technology will help you make better decisions that'll benefit your organization.