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="http://10.20.160.198/wiki/display/dubbo/10.20.153.186" /> <bean id="demoService" class="com.alibaba.dubbo.callback.implicit.NormalDemoService" /> <dubbo:service interface="com.alibaba.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 = "com.alibaba.dubbo.callback.implicit.NofifyImpl" /> <dubbo:reference id="demoService" interface="com.alibaba.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"); NofifyImpl notify = (NofifyImpl) 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());
NOTE2.0.7+
version,async=false
is default.