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Advanced Techniques in Go Programming

Solution 3: Working with gRPC

Explore how to implement gRPC services in Go by creating a RESTful server using the Gin framework that interacts with a gRPC server via protocol buffers. Understand setting up endpoints that call gRPC methods, establish connections with grpc.Dial, and handle JSON responses for data exchange.

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Solution

Here is a RESTful service that uses gRPC for data exchange. To execute the RESTful service:

  • Open a new terminal window and execute the rServer.go code using the following commands:

export GOROOT=/usr/local/go; export GOPATH=$HOME/go; export PATH=$GOPATH/bin:$GOROOT/bin:$PATH; cd usercode;
go run rServer.go

  • Then, open another terminal window and execute the following curl commands:

# curl http://localhost:8081/datetime
# curl http://localhost:8081/randompassword
# curl http://localhost:8081/randominteger 
package main

import (
    "context"
    "github.com/gin-gonic/gin"
    "google.golang.org/grpc"
    "log"
    "net/http"
    "os"
    "github.com/Educative-Content/protoapi"
)

var grpcServerAddress = "localhost:8082" 

func main() {
    router := gin.Default()

    // Initialize a gRPC connection to the server
    conn, err := grpc.Dial(grpcServerAddress, grpc.WithInsecure())
    if err != nil {
        log.Fatalf("Failed to connect to gRPC server: %v", err)
    }
    defer conn.Close()

    client := protoapi.NewRandomClient(conn)

    // Define RESTful API endpoints
    router.GET("/datetime", func(c *gin.Context) {
        ctx := context.Background()
        response, err := client.GetDate(ctx, &protoapi.RequestDateTime{})
        if err != nil {
            c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
            return
        }
        c.JSON(http.StatusOK, gin.H{"datetime": response.Value})
    })

    router.GET("/randompassword", func(c *gin.Context) {
        ctx := context.Background()
        response, err := client.GetRandomPass(ctx, &protoapi.RequestPass{Seed: 100, Length: 8})
        if err != nil {
            c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
            return
        }
        c.JSON(http.StatusOK, gin.H{"password": response.Password})
    })

    router.GET("/randominteger", func(c *gin.Context) {
        ctx := context.Background()
        response, err := client.GetRandom(ctx, &protoapi.RandomParams{Seed: 100, Place: 1})
        if err != nil {
            c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
            return
        }
        c.JSON(http.StatusOK, gin.H{"integer": response.Value})
    })

    port := getPort()
    router.Run(":" + port)
}

func getPort() string {
    if len(os.Args) > 1 {
        return os.Args[1]
    }
    return "8081" // Default port
}
gServer.go and rServer,go

Code

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