ballerina 的grpc 開發模型，對於開發者來說簡單了好多，不是schema first 的方式，而是我們
只要編寫簡單的ballerina service 就可以了，proto 檔案是自動幫我們生成的，同時我們用這個
檔案方便的生成各種客戶端的程式碼

專案準備

• 專案結構

├── Ballerina.toml
├── grpc_service
│ └── order_mgt_service.bal

• grpc 程式碼

  可以看出就是普通的ballerina service

import ballerina/grpc;

// gRPC service endpoint definition.
endpoint grpc:Listener listener {
    host:"localhost",
    port:9090
};

// Order management is done using an in memory map.
// Add sample orders to the 'orderMap' at startup.
map<orderInfo> ordersMap;

// Type definition for an order.
type orderInfo record {
    string id;
    string name;
    string description;
};

// gRPC service.
@grpc:ServiceConfig
service orderMgt bind listener {

    // gRPC method to find an order.
    findOrder(endpoint caller, string orderId) {
        string payload;
        // Find the requested order from the map.
        if (ordersMap.hasKey(orderId)) {
            json orderDetails = check <json>ordersMap[orderId];
            payload = orderDetails.toString();
        } else {
            payload = "Order : '" + orderId + "' cannot be found.";
        }

        // Send response to the caller.
        _ = caller->send(payload);
        _ = caller->complete();
    }

    // gRPC method to create a new Order.
    addOrder(endpoint caller, orderInfo orderReq) {
        // Add the new order to the map.
        string orderId = orderReq.id;
        ordersMap[orderReq.id] = orderReq;
        // Create a response message.
        string payload = "Status : Order created; OrderID : " + orderId;

        // Send a response to the caller.
        _ = caller->send(payload);
        _ = caller->complete();
    }

    // gRPC method to update an existing Order.
    updateOrder(endpoint caller, orderInfo updatedOrder) {
        string payload;
        // Find the order that needs to be updated.
        string orderId = updatedOrder.id;
        if (ordersMap.hasKey(orderId)) {
            // Update the existing order.
            ordersMap[orderId] = updatedOrder;
            payload = "Order : '" + orderId + "' updated.";
        } else {
            payload = "Order : '" + orderId + "' cannot be found.";
        }

        // Send a response to the caller.
        _ = caller->send(payload);
        _ = caller->complete();
    }

    // gRPC method to delete an existing Order.
    cancelOrder(endpoint caller, string orderId) {
        string payload;
        if (ordersMap.hasKey(orderId)) {
            // Remove the requested order from the map.
            _ = ordersMap.remove(orderId);
            payload = "Order : '" + orderId + "' removed.";
        } else {
            payload = "Order : '" + orderId + "' cannot be found.";
        }

        // Send a response to the caller.
        _ = caller->send(payload);
        _ = caller->complete();
    }
}
 

生成proto&&客戶端程式碼

• proto生成

ballerina build grpc_service/

• 客戶端程式碼

ballerina grpc --input target/grpc/orderMgt.proto --output grpc_client

• 修改生成的客戶端程式碼

import ballerina/log;
import ballerina/grpc;

// This is client implementation for unary blocking scenario
public function main(string... args) {
    // Client endpoint configuration
    endpoint orderMgtBlockingClient orderMgtBlockingEp {
        url:"http://localhost:9090"
    };

    // Create an order
    log:printInfo("-----------------------Create a new order-----------------------");
    orderInfo orderReq = {id:"100500", name:"XYZ", description:"Sample order."};
    var addResponse = orderMgtBlockingEp->addOrder(orderReq);
    match addResponse {
        (string, grpc:Headers) payload => {
            string result;
            grpc:Headers resHeaders;
            (result, resHeaders) = payload;
            log:printInfo("Response - " + result + "\n");
        }
        error err => {
            log:printError("Error from Connector: " + err.message + "\n");
        }
    }

    // Update an order
    log:printInfo("--------------------Update an existing order--------------------");
    orderInfo updateReq = {id:"100500", name:"XYZ", description:"Updated."};
    var updateResponse = orderMgtBlockingEp->updateOrder(updateReq);
    match updateResponse {
        (string, grpc:Headers) payload => {
            string result;
            grpc:Headers resHeaders;
            (result, resHeaders) = payload;
            log:printInfo("Response - " + result + "\n");
        }
        error err => {
            log:printError("Error from Connector: " + err.message + "\n");
        }
    }

    // Find an order
    log:printInfo("---------------------Find an existing order---------------------");
    var findResponse = orderMgtBlockingEp->findOrder("100500");
    match findResponse {
        (string, grpc:Headers) payload => {
            string result;
            grpc:Headers resHeaders;
            (result, resHeaders) = payload;
            log:printInfo("Response - " + result + "\n");
        }
        error err => {
            log:printError("Error from Connector: " + err.message + "\n");
        }
    }

    // Cancel an order
    log:printInfo("-------------------------Cancel an order------------------------");
    var cancelResponse = orderMgtBlockingEp->cancelOrder("100500");
    match cancelResponse {
        (string, grpc:Headers) payload => {
            string result;
            grpc:Headers resHeaders;
            (result, resHeaders) = payload;
            log:printInfo("Response - " + result + "\n");
        }
        error err => {
            log:printError("Error from Connector: " + err.message + "\n");
        }
    }
}
 

執行&&測試

• 執行server

ballerina run grpc_service

• client 呼叫

ballerina run grpc_client

參考資料