GraphQL vs gRPC

GraphQL and REST are not the only API technologies. There is also gRPC, an open-source Remote Procedure Call framework that enables you to build APIs. In this section, you will see how gRPC differs & compares to GraphQL.

How does gRPC work?

The "RPC" part of the name stands for "Remote Procedure Call", which indicates how the communication happens. In gRPC, the client communicates with the server by calling its methods as if they were local. That's possible by creating a stub (client) with the same methods as the gRPC server. You then use the client to call the server methods.

They exchange data using Protobuf (Protocol buffers), compared to GraphQL, which uses text-based JSON to exchange data. Protobuf is more of a mechanism that serializes structured data into binary format. If you want to learn more about Protocol buffers, you can do it here.

Similar to GraphQL, gRPC has a schema-like file, .proto, that describes the API service. It specifies the available methods that can be called and their parameters & return types. The default and most common Interface Definition Language (IDL) for writing "proto" files is Protobuf (Protocol buffers).

Consider the following example:

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syntax = "proto3";

service User {
  rpc GetUser (UserRequest) returns (UserResponse) {}
}

message UserRequest {
  int32 id = 1;
}

message UserResponse {
  string name = 1;
  int32 age = 1;
  string address = 1;
}

The above code defines a service that allows you to retrieve the details about a specific user. The GetUser method represents the API endpoint the client can call to retrieve a user.

Due to the .proto files and Protocol buffers, gRPC can auto-generate the client & server boilerplate code for yourself in various programming languages.

gRPC Benefits

One benefit of using gRPC is the performance of data exchange. gRPC uses Protobuf to serialize data into binary format, which improves the payload size. As a result, exchanging data is faster and more efficient.

gRPC also uses the HTTP/2 transport protocol, which comes with request and response multiplexing. In HTTP/2, the request/response is split into multiple frames that are sent individually and put together back when they arrive at the destination. That makes it possible to transfer multiple requests and responses in one connection.

Another advantage of using gRPC is that it supports various streaming types. It supports

• Server streaming - the client makes a request, and the server responds with a stream of messages
• Client streaming - the client sends a stream of messages to the server, which responds after the client has finished streaming
• Bidirectional streaming - both the client and server send independent streams of messages to each other

gRPC also supports Unary interactions, where the client sends one request, and the server sends one response back.

Code generation is another benefit. gRPC's protoc compiler can use the .proto file to generate server and client code in 11 programming languages.

gRPC Drawbacks

One drawback is that Protobuf (Protocol buffers), a core part of gRPC, only supports code generated in 11 languages: C#/.NET, C++, Dart, Go, Java, Kotlin, Node, Objective-C, PHP, Python and Ruby.

Another drawback is that gRPC uses Protobuf to exchange data. As a result, the messages are not human readable. Reading and inspecting data requires extra steps and tools.

GraphQL vs gRPC

When it comes to data fetching, GraphQL is more precise than gRPC. That means you can retrieve exactly the data you want - nothing more, nothing less. gRPC, with certain API designs, might return extra data from the server (similar to REST).

Regarding performance, gRPC is considerably faster than GraphQL, thanks to Protobuf and HTTP/2. The payload data is serialized into binary format, which reduces its size and makes it more efficient than text-based formats JSON or XML.

gRPC comes with native support for code generation, whereas for GraphQL, you need third-party tools. gRPC can generate server and client code from the .proto file without requiring third-party tools.

Another difference is that gRPC does not come with browser support because browsers do not support HTTP/2 yet. Since GraphQL uses HTTP/1.1, it does not have this problem.

There is also a difference in the way messages are formatted. gRPC uses Protobuf, which is not human readable, whereas GraphQL uses human-readable formats such as JSON or XML.

Lastly, gRPC is more challenging to learn due to the use of Protocol buffers and HTTP/2. It also has limited community support & learning materials compared to GraphQL.

It's important to mention that both technologies are great for specific use cases. No technology is a one size fits all solution. It's also possible to combine both to build a better solution.