Before calling, after calling, when an exception occurs,will trigger oninvoke
, onreturn
, onthrow
events.You can configure which method to notify when an event occurs.
interface IDemoService {
public Person get(int id);
}
class NormalDemoService implements IDemoService {
public Person get(int id) {
return new Person(id, "charles`son", 4);
}
}
<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"/>
interface Notify {
public void onreturn(Person msg, Integer id);
public void onthrow(Throwable ex, Integer id);
}
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);
}
}
<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>
callback
and async
functions are orthogonally decomposed. async = true
means that the result is returned immediately. onreturn
means that a callback is required.
There are several situations with the tow attributes[^2].
async=true onreturn="xxx"
async=false onreturn="xxx"
async=true
async=true
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:Just used to illustrate the normal callback callback, the specific business decisions.
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());
2.0.7+
version, the default value is async=false
.