调用触发事件通知

调用前后发生异常时的事件通知

功能描述

调用前、调用后和发生异常时，会触发三个事件 oninvoke、onreturn 和 onthrow。您可以配置当事件发生时通知哪个类的哪个方法。

参考用例

https://github.com/apache/dubbo-samples/tree/master/dubbo-samples-notify

使用场景

在调用服务方法之前，我们可以记录开始时间，调用结束后，我们可以统计整个调用耗时。发生异常时，我们可以发出警告或打印错误日志，或者记录调用服务前后请求日志和响应日志。

使用方法

interface IDemoService {
    public Person get(int id);
}

服务提供者实现

class NormalDemoService implements IDemoService {
    public Person get(int id) {
        return new Person(id, "charles`son", 4);
    }
}

服务提供者配置

<dubbo:application name="rpc-callback-demo" />
<dubbo:registry address="zookeeper://127.0.0.1:2181"/>
<bean id="demoService" class="org.apache.dubbo.callback.implicit.NormalDemoService" />
<dubbo:service interface="org.apache.dubbo.callback.implicit.IDemoService" ref="demoService" version="1.0.0" group="cn"/>

服务消费者回调接口

interface Notify {
    public void onreturn(Person msg, Integer id);
    public void onthrow(Throwable ex, Integer id);
}

服务消费者回调实现

class NotifyImpl implements Notify {
    public Map<Integer, Person> ret = new HashMap<Integer, Person>();
    public Map<Integer, Throwable> errors = new HashMap<Integer, Throwable>();
    
    public void onreturn(Person msg, Integer id) {
        System.out.println("onreturn:" + msg);
        ret. put(id, msg);
    }
    
    public void onthrow(Throwable ex, Integer id) {
        errors. put(id, ex);
    }
}

服务消费者回调配置

两者有以下组合

异步回调模式：async=true onreturn="xxx"
同步回调模式：async=false onreturn="xxx"
异步无回调：async=true
同步无回调：async=false

callback 和 async 函数正交分解，async=true 表示是否立即返回结果，async=false 为默认值，onreturn 表示是否需要回调。

<bean id="demoCallback" class = "org.apache.dubbo.callback.implicit.NotifyImpl" />
<dubbo:reference id="demoService" interface="org.apache.dubbo.callback.implicit.IDemoService" version="1.0.0" group="cn">
      <dubbo:method name="get" async="true" onreturn = "demoCallback.onreturn" onthrow="demoCallback.onthrow" />
</dubbo:reference>

测试代码

IDemoService demoService = (IDemoService) context. getBean("demoService");
NotifyImpl notify = (NotifyImpl) context. getBean("demoCallback");
int requestId = 2;
Person ret = demoService. get(requestId);
Assert.assertEquals(null, ret);
//for Test: It is only used to illustrate that the callback is called normally, and the specific implementation of the business is determined by itself.
for (int i = 0; i < 10; i++) {
    if (!notify.ret.containsKey(requestId)) {
        Thread. sleep(200);
    } else {
        break;
    }
}
Assert.assertEquals(requestId, notify.ret.get(requestId).getId());

上次修改时间：2023 年 1 月 2 日：增强 en 文档 (#1798) (95a9f4f6c1c)