@fmuyassarov

  • A communication system for handling request/response interactions and temporary streaming.

  • A client application can call a method on a server application running on another machine just like it would a local function.

  • Server implements the interface and runs a gRPC server to handle client requests.

  • Client (a.k.a.) stub, provides the same methods as the server.

  • Relies on Protocol Buffer for message serialization (can be replaced by JSON)

  • Relies on HTTP/2 as transport layer

  • Pluggable auth, tracing, load balancing and health checking

  • 11 supported languages (C++, Go, Python, Java etc)

  • Open sourced by google in 2015 as the replacement for Stubby (micro services communication framework)

Facts about gRPC...

Basic components

000110101011011101

gRPC
client

HTTP/2

network

gRPC
server

  • protocol buffer
  • HTTP/2
  • channel
    • a virtual connection
  • stub
  • service methods
var opts []grpc.DialOption

opts = append(opts, grpc.WithTransportCredentials(insecure.NewCredentials()))
conn, err := grpc.NewClient(*serverAddr, opts...)

Basic components of gRPC

gRPC
client

gRPC
server

request

Unary RPC

response

rpc SayHello(HelloRequest) returns (HelloResponse);
  • protocol buffer
  • HTTP/2
  • channel
  • stub
  • service methods

Basic components of gRPC

gRPC
client

gRPC
server

request

response

Server streaming RPC

rpc LotsOfReplies(HelloRequest) returns (stream HelloResponse);
  • protocol buffer
  • HTTP/2
  • channel
  • stub
  • service methods

Basic components of gRPC

gRPC
client

gRPC
server

request

response

Client streaming RPC

rpc LotsOfGreetings(stream HelloRequest) returns (HelloResponse);
  • protocol buffer
  • HTTP/2
  • channel
  • stub
  • service methods

Basic components of gRPC

gRPC
client

gRPC
server

request

response

Bidirectional streaming RPC

rpc BidiHello(stream HelloRequest) returns (stream HelloResponse);
  • protocol buffer
  • HTTP/2
  • channel
  • stub
  • service methods

Basic components of gRPC

  • protocol buffer
  • HTTP/2
  • channel
  • stub
  • service methods
  • synchronous vs asynchronous
  • protocol buffer
  • HTTP/2
  • channel
  • stub
  • service methods
  • synchronous vs asynchronous
  • Timeouts/Deadline
    • Timeouts and Deadlines control how long a gRPC call should wait before failing.
    • A Deadline is the specific time by which a request must complete (e.g., 5 seconds from now).
    • A Timeout is the maximum duration a call can take (e.g., 5 seconds).
    • If a request exceeds the deadline or timeout, gRPC cancels the call and returns a DEADLINE_EXCEEDED error.
    • Clients set deadlines, and servers can check them to avoid unnecessary processing.

Basic components of gRPC

  • protocol buffer
  • HTTP/2
  • channel
  • stub
  • service methods
  • synchronous vs asynchronous
  • Timeouts/Deadline
    • Timeouts and Deadlines control how long a gRPC call should wait before failing.
    • A Deadline is the specific time by which a request must complete (e.g., 5 seconds from now).
    • A Timeout is the maximum duration a call can take (e.g., 5 seconds).
    • If a request exceeds the deadline or timeout, gRPC cancels the call and returns a DEADLINE_EXCEEDED error.
    • Clients set deadlines, and servers can check them to avoid unnecessary processing.
  • RPC termination
    • can be independently terminated either by client or server

Basic components of gRPC

Protocol Buffer (language)

Protobuf

  • A mechanism for serializing structured data (think of it similar but better version of JSON)
  • Binary format - it’s more compact than text-based JSON with a lot of overhead (brackets, keys, etc.).
  • Faster serialization/de-serialization – since Protobuf is binary, encoding and decoding are much faster compared to JSON, which requires parsing text.

  • Strongly typed – enforces data types (int32, float, string)

  • Backward compatibility – allows to add/remove fields without breaking older clients

  • Unlike JSON (gzip), it doesn't require extra tooling for reducing the payload size

  • Since it is in binary format, it is NOT human readable nor a self describing/human readable language

000110101011011101

gRPC
client

HTTP/2

gRPC
server

Scheme
.proto

network

Let's build ...

  • protoc - a compiler that reads .proto files and generates code in different languages with the help of plugins.
  • protoc-gen-go - a Go plugin for protoc that generates Go structures and serialization methods for Protocol Buffers (but without gRPC support).

Let's build ...

  • protoc - a compiler that reads .proto files and generates code in different languages with the help of plugins.
  • protoc-gen-go - a Go plugin for protoc that generates Go structures and serialization methods for Protocol Buffers (but without gRPC support). 
message User {
  string name = 1;
  int32 age = 2;
}

type User struct {
    Name string
    Age  int32
}

Let's build ...

  • protoc - a compiler that reads .proto files and generates code in different languages with the help of plugins.
  • protoc-gen-go - a Go plugin for protoc that generates Go structures and serialization methods for Protocol Buffers (but without gRPC support).
  • protoc-gen-go-grpc - a gRPC plugin for protoc that generates Go code specifically for gRPC server and client stubs from .proto files. 
message User {
  string name = 1;
  int32 age = 2;
}

type User struct {
    Name string
    Age  int32
}

Let's build ...

  • protoc - a compiler that reads .proto files and generates code in different languages with the help of plugins.
  • protoc-gen-go - a Go plugin for protoc that generates Go structures and serialization methods for Protocol Buffers (but without gRPC support).
  • protoc-gen-go-grpc - a gRPC plugin for protoc that generates Go code specifically for gRPC server and client stubs from .proto files. 
service UserService {
  rpc GetUser (UserRequest) returns (UserResponse);
}

type UserServiceServer interface {
    GetUser(context.Context, *UserRequest) (*UserResponse, error)
}

At this point, we have a Go interface, but we still need to implement it.

protoc hello/hello.proto \
	--go_out=. \
    --go-grpc_out=. \
    --go_opt=paths=source_relative \
    --go-grpc_opt=paths=source_relative
protoc hello/hello.proto \
	--go_out=. \
    --go-grpc_out=. \
    --go_opt=paths=source_relative \
    --go-grpc_opt=paths=source_relative

ls -l hello
total 40
-rw-r--r--@ 1 est  staff  6127 Feb 24 15:57 hello.pb.go
-rw-r--r--@ 1 est  staff   277 Feb 24 15:43 hello.proto
-rw-r--r--@ 1 est  staff  4688 Feb 24 15:57 hello_grpc.pb.go

  • hello.pb.go - interface types for servers to implement  

  • hello_grpc.pb.go - protocol buffer code (for populating, serializing and retrieve messages.

demo time ...

gRPC

By fmuyassarov

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gRPC

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