PHP implements the open source Apache Dubbo framework

Apache Dubbo is a high-performance RPC framework based on Java language, open sourced by Alibaba. With the widespread use of the PHP language in web applications, more and more PHP programmers hope to use Dubbo's high-performance features to implement distributed service calls. For this purpose, we can implement the Dubbo framework through the PHP language.

1. The basic principles of Dubbo

Dubbo solves the communication problems in distributed applications very well. When we use the Dubbo framework, we need to rely on two key concepts: provider and consumer. Providers publish services to the registry, and consumers subscribe to services from the registry. When a consumer needs to call a service, it will select a provider through the load balancing algorithm and implement the call through Dubbo's remote calling mechanism.

Dubbo's architecture is mainly divided into three layers: service governance layer, service invocation layer and protocol layer. The service governance layer mainly provides the functions of the registration center; the service invocation layer mainly implements Dubbo's remote calling mechanism; the protocol layer mainly implements Dubbo's protocol.

Dubbo's remote calling mechanism is mainly divided into three steps: serialization, transmission and deserialization. First, the caller serializes the request parameters, then transmits them to the provider through the network, deserializes them at the provider, and serializes the results back to the caller after processing, and finally deserializes them at the caller.

2. The idea of ​​​​implementing the Dubbo framework in PHP

We divide the functions of the Dubbo framework into two parts: service registration and service invocation. Service registration refers to registering the services provided in the registration center and providing IP, port and other information. When the server starts, it will register the provided services in the registration center. Service invocation means that the consumer subscribes to the corresponding service from the registration center, selects the provider through the load balancing algorithm when requesting, and calls the provider's service remotely.

We use PHP's Swoole to implement the Dubbo framework. Swoole is a network communication framework for PHP that supports asynchronous, concurrency, and coroutine features. We implement the service registration as a Swoole TCP server, and the provider will register the provided services with the server when it starts. On the consumer side, we connect to the registration center through Swoole's TCP client and obtain the required services.

3. Specific steps to implement Dubbo framework in PHP

1. Service registration

The service provider will start a TCP server and listen to the specified IP and port . When a client connects, Swoole's onConnect event will be triggered. In the onConnect event, we can send the service provider's information to the registration center. The following is the basic code implementation:

//启动 TCP 服务器
$server = new SwooleServer($host, $port, SWOOLE_PROCESS, SWOOLE_SOCK_TCP);

//监听连接事件
$server->on('connect', function ($server, $fd) use ($provider) {
    //将提供的服务信息发送给注册中心
    $message = [
        'type' => 'register',
        'serviceName' => $provider['serviceName'],
        'ip' => $provider['ip'],
        'port' => $provider['port'],
    ];
    $server->send($fd, json_encode($message));
});

//启动服务器
$server->start();

2. Service subscription

The service consumer will start a TCP client and connect to the registration center to obtain the provider information of the required service. The following is the basic code implementation:

//创建 TCP 客户端
$client = new SwooleClient(SWOOLE_SOCK_TCP);

//连接至注册中心
$client->connect($host, $port);

//发送获取服务提供者信息的请求
$message = [
    'type' => 'subscribe',
    'serviceName' => $serviceName,
];
$client->send(json_encode($message));

//监听服务提供者信息
$client->on('receive', function ($client, $data) use ($serviceName) {
    //解析从注册中心获取的服务提供者信息
    $providersInfo = json_decode($data, true);
    //根据负载均衡算法获取提供者，并远程调用服务
    $provider = loadBalance($providersInfo);
    callRemoteService($provider['ip'], $provider['port'], $serviceName, $params);
});

3. Remote call service

The consumer connects to the corresponding provider through the TCP client and sends parameter information to the provider. After receiving the request, the provider processes it accordingly and returns the result to the consumer. The following is the basic code implementation:

$request = [
    'path' => $serviceName,
    'method' => $methodName,
    'params' => $params,
];

//连接至服务提供者
$client = new SwooleClient(SWOOLE_SOCK_TCP);
$client->connect($ip, $port);

//将请求信息发送给提供者
$client->send(json_encode($request));

//接收并解析提供者返回的结果
$result = json_decode($client->recv(), true);

//返回调用结果
return $result;

IV. Summary

This article introduces how to use the PHP language to implement the Dubbo framework. We implement service registration and service subscription functions through Swoole. When calling the service remotely, use the TCP client to establish a connection with the service provider and send the request parameter information to the provider. The provider processes the request after receiving it and returns the result to the consumer. Of course, the above is just the basic implementation of the Dubbo framework. In actual applications, it is also necessary to handle abnormal situations and implement more service governance and monitoring functions.

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