If a ServiceAbility wants to interact with a PageAbility or a ServiceAbility in another application, you must first create a connection by calling connectAbility(). The connectAbility() method of the PageAbility is defined in featureAbility, and the connectAbility() method of the ServiceAbility is defined in particleAbility. For details about the connection rules, see Component Startup Rules. When using connectAbility() to process the callback, pass in the instances of Want and IAbilityConnection of the target ServiceAbility. IAbilityConnection provides the following callbacks that you should implement.

Table 1 IAbilityConnection APIs

The following sample code enables the PageAbility to create connection callback instances and connect to the local ServiceAbility:

import featureAbility from '@ohos.ability.featureAbility';
import common from '@ohos.app.ability.common';
import Want from '@ohos.app.ability.Want';
import promptAction from '@ohos.promptAction';
import rpc from '@ohos.rpc';
import hilog from '@ohos.hilog';

const LOG_TAG: string = '[Sample_FAModelAbilityDevelop]';
const LOG_DOMAIN: number = 0xFF00;
let option: common.ConnectOptions = {
  onConnect: (element, proxy) => {
    hilog.info(LOG_DOMAIN, LOG_TAG, 'onConnectLocalService onConnectDone element:' + JSON.stringify(element));
    if (proxy === null) {
      promptAction.showToast({
        message: 'connect service failed'
      });
      return;
    }
    let data = rpc.MessageParcel.create();
    let reply = rpc.MessageParcel.create();
    let option = new rpc.MessageOption();
    data.writeInterfaceToken('connect.test.token');
    proxy.sendRequest(0, data, reply, option);
    promptAction.showToast({
      message: 'connect service success'
    });
  },
  onDisconnect: (element) => {
    hilog.info(LOG_DOMAIN, LOG_TAG, `onConnectLocalService onDisconnectDone element:${element}`);
    promptAction.showToast({
      message: 'disconnect service success'
    });
  },
  onFailed: (code) => {
    hilog.info(LOG_DOMAIN, LOG_TAG, `onConnectLocalService onFailed errCode:${code}`);
    promptAction.showToast({
      message: 'connect service failed'
    });
  }
};

let request: Want = {
  bundleName: 'com.samples.famodelabilitydevelop',
  abilityName: 'com.samples.famodelabilitydevelop.ServiceAbility',
};
let connId = featureAbility.connectAbility(request, option);
hilog.info(LOG_DOMAIN, LOG_TAG, `connectAbility id:${connId}`);

When the ServiceAbility is connected, the onConnect() callback is invoked and returns an IRemoteObject defining the proxy used for communicating with the ServiceAbility. The system provides a default implementation of IRemoteObject. You can extend rpc.RemoteObject to implement your own class of IRemoteObject.

The following sample code shows how the ServiceAbility returns itself to the caller:

import type Want from '@ohos.app.ability.Want';
import rpc from '@ohos.rpc';
import hilog from '@ohos.hilog';

const TAG: string = '[Sample_FAModelAbilityDevelop]';
const domain: number = 0xFF00;

class FirstServiceAbilityStub extends rpc.RemoteObject {
  constructor(des: Object) {
    if (typeof des === 'string') {
      super(des);
    } else {
      return;
    }
  }

  onRemoteRequest(code: number, data: rpc.MessageParcel, reply: rpc.MessageParcel, option: rpc.MessageOption): boolean {
    hilog.info(domain, TAG, 'ServiceAbility onRemoteRequest called');
    if (code === 1) {
      let string = data.readString();
      hilog.info(domain, TAG, `ServiceAbility string=${string}`);
      let result = Array.from(string).sort().join('');
      hilog.info(domain, TAG, `ServiceAbility result=${result}`);
      reply.writeString(result);
    } else {
      hilog.info(domain, TAG, 'ServiceAbility unknown request code');
    }
    return true;
  }
}
//...