How to implement rpc in golang

In recent years, with the rapid development of the Internet, distributed systems have attracted more and more attention. RPC (Remote Procedure Call) technology is a key technology in distributed systems, which allows different systems to communicate and collaborate with each other. Among different languages, most languages ​​have their own RPC framework. In this article, we will introduce how to use Golang to implement RPC so that systems can collaborate happily.

1. The basic concept of RPC

1.1. What is

RPC is remote procedure call (Remote Procedure Call), which means that the client calls a remote service locally , just like calling native code, and can pass parameters and get return values ​​just like calling native code. It actually abstracts the network communication process into a pattern similar to local calls.

1.2. Why

In a distributed system, each node is dispersed and each undertakes different tasks or business services. For these nodes to work together, they need to communicate over the network. RPC allows these nodes to exchange data through the network to implement business logic execution.

1.3. Features

The core principle of RPC is to abstract the network communication process into a local calling process. The client passes the parameters locally to the remote service, and the server processes the parameters and then Return the processing results to the client. This allows various nodes in the distributed system to cooperate with each other to complete various tasks of the distributed system. The characteristics of RPC are as follows:

• Abstraction: The network communication process is abstracted into a local calling process, so that developers using the RPC framework can use remote services like local services.
• Transparent: RPC shields most communication-related details for users, allowing developers to focus more on business logic.
• Efficient: RPC uses binary to transmit data, with high serialization and deserialization efficiency and fast transmission speed. It can transmit a large amount of data when the network bandwidth is small.

2. Basic steps for implementing RPC in Golang

2.1. Define the interface

In Golang, you first need to define the interface to be exposed. This interface is equivalent to Function prototype for remote calls.

type Server struct {}

type Args struct {
    A, B int
}

func (s *Server) Multiply(args *Args, reply *int) error {
    *reply = args.A * args.B
    return nil
}

In the code, a Server structure and an Args structure are defined. The Server structure defines a Multiply function. The Multiply function is used to calculate the product of two integers. It should be noted that the parameters and return value of the Multiply function must meet the RPC specifications.

2.2. Register RPC service

After defining the interface, you need to register the interface into the RPC service so that the client can call the RPC service. To register the service with the RPC server, we need to use the rpc.Serve() function in Golang.

func main() {
    server := new(Server)
    rpc.Register(server)
    rpc.HandleHTTP()

    listener, err := net.Listen("tcp", ":8080")
    if err != nil {
        log.Fatal("listen error:", err)
    }

    http.Serve(listener, nil)
}

In the above code, we first create a Server structure, then register the interface defined in the Server structure to the RPC server through the rpc.Register function, and then use rpc.HandleHTTP() to The RPC server is bound to the default mux in the http package, and finally the RPC server is bound to the TCP listening address through http.Serve.

2.3. Write client code

After the RPC service registration is completed, we need to write client code to call the RPC service. Golang's rpc package provides the rpc.DialHTTP function, which can be used to establish an RPC client connection. The following is a simple RPC client implementation:

func main() {
    client, err := rpc.DialHTTP("tcp", "localhost:8080")
    if err != nil {
        log.Fatal("dialing:", err)
    }

    args := &Args{7, 8}
    var reply int
    err = client.Call("Server.Multiply", args, &reply)
    if err != nil {
        log.Fatal("Server error:", err)
    }

    fmt.Printf("Multiply: %d*%d=%d", args.A, args.B, reply)
}

The client establishes a connection with the RPC server through the rpc.DialHTTP function, and then calls the client.Call method to execute the RPC server function. The first parameter of Call is the name of the function to be called, the second parameter is the parameter of the function, and the third parameter is the return value of the function.

3. Golang RPC example code

The following is a complete example of implementing RPC based on Golang:

package main

import (
    "fmt"
    "log"
    "net"
    "net/http"
    "net/rpc"
)

type Server struct{}

type Args struct {
    A, B int
}

func (s *Server) Multiply(args *Args, reply *int) error {
    *reply = args.A * args.B
    return nil
}

func main() {
    server := new(Server)
    rpc.Register(server)
    rpc.HandleHTTP()

    listener, err := net.Listen("tcp", ":8080")
    if err != nil {
        log.Fatal("listen error:", err)
    }

    go http.Serve(listener, nil)

    client, err := rpc.DialHTTP("tcp", "localhost:8080")
    if err != nil {
        log.Fatal("dialing:", err)
    }

    args := &Args{7, 8}
    var reply int
    err = client.Call("Server.Multiply", args, &reply)
    if err != nil {
        log.Fatal("Server error:", err)
    }

    fmt.Printf("Multiply: %d*%d=%d", args.A, args.B, reply)
}

Through the above code, we can see that in In Golang, implementing RPC is very simple. You only need to define the interface, register the RPC service, and write client code. Of course, both RPC clients and servers can be heterogeneous, which is very useful when scaling distributed systems.

4. Summary

This article introduces what RPC is, why RPC is needed, and how to use Golang to implement RPC. By reading this article, we can understand that RPC is widely used and is a basic technology in distributed systems. As an efficient programming language, Golang has an excellent RPC framework, which can help developers better implement distributed systems. If you need to develop a distributed system, you might as well try using Golang to implement RPC.

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