How to Communicate with a Portal Web Application
The PortalsPlugin
provides useful features to aid in communication between your Web and Native applications. It is included in the Ionic Portals library by default and takes advantage of the Capacitor Plugin system.
Setup
Android
Follow the Getting Started Guide to install the Ionic Portals library into your native mobile projects. The PortalsPlugin
is automatically added to every instance of a Portal.
Web
Install the Ionic Portals package from NPM into your web application.
npm install @ionic/portals
Initial Context
The Initial Context mechanism allows you to pass data to your web application from native so that it is available for when the web application initially loads.
Setting Initial Context
Initial context data can be set in two different ways. You may want to set it when building a new Portal using PortalManager
.
- Kotlin
- Java
PortalManager.newPortal("maps")
.setStartDir("web")
.setInitialContext(mapOf("ic_example" to "hello world"))
.create()
PortalManager.newPortal("maps")
.setStartDir("web")
.setInitialContext(Map.of("ic_example", "hello world"))
.create();
You can also set Initial Context data on a Portal
object prior to the Portal loading.
- Kotlin
- Java
val mapsPortal = PortalManager.getPortal("maps")
mapsPortal?.setInitialContext(mapOf("ic_example" to "hello world"))
Portal mapsPortal = PortalManager.getPortal("maps");
mapsPortal.setInitialContext(Map.of("ic_example", "hello world"));
Using Initial Context
To access the initial context set from the native application in your web application, import getInitialContext
from @ionic/portals
use the getInitialContext() function.
import { getInitialContext } from "@ionic/portals";
const initialContext = getInitialContext<{ ic_example: string }>();
// prints "hello world" in this example
console.log(initialContext?.value?.ic_example);
Initial context is useful when using a Single Page Application (SPA) across multiple Portals in your application. The route to a specific section of the SPA can be passed in as initial context data. Your web application can then use it to load that section directly without need for a redirect. Check out our how-to guide.
Communicating via Pub/Sub
The Publish and Subscribe mechanism (pub/sub) built into the PortalsPlugin
allows you to send data between your web and native applications through a Portal.
Defining Subscribers
Subscribers listen for messages sent to a certain topic. They can be defined in your web application to listen for messages published from native, and vice versa.
To listen for a message published from the native side of a Portal, define a subscriber in your web application.
const portalSubscription = await Portals.subscribe({ topic }, (result) => {
console.log(JSON.stringify(result));
});
To listen for messages published from the web side of a Portal, define a subscriber in your native application.
- Kotlin
- Java
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
// ...
val portal = PortalManager.getPortal("example")
val portalFragment = PortalFragment(portal)
// listen on the topic "dismiss" and act on the result data.
// This is an example to dismiss a containing native DialogFragment.
PortalsPlugin.subscribe("dismiss") { result ->
if (result.data == "cancel" || result.data == "success") {
this.dismiss()
}
}
// ...
// add the PortalFragment to the example container fragment
val fragmentManager = childFragmentManager
fragmentManager.beginTransaction().replace(R.id.example_web_app, portalFragment!!).commit()
}
@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// ...
Portal portal = PortalManager.getPortal("example");
PortalFragment portalFragment = new FadePortalFragment(portal);
// listen on the topic "dismiss" and act on the result data.
// This is an example to dismiss a containing native DialogFragment.
PortalsPlugin.subscribe("dismiss", (subscriptionResult -> {
if(subscriptionResult.getData().equals("cancel")
|| subscriptionResult.getData().equals("success")) {
this.dismiss();
}
return Unit.INSTANCE;
}));
// ...
// add the PortalFragment to the example container fragment
final FragmentManager fragmentManager = getChildFragmentManager();
fragmentManager.beginTransaction().replace(R.id.example_web_app, portalFragment).commit();
}
Subscribe Using Annotations
Android also provides a way to link subscribers defined as methods with annotations.
- Kotlin
- Java
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
// ...
val portal = PortalManager.getPortal("example")
val portalFragment = PortalFragment(portal)
// register this class as having defined message subscribers
portalFragment!!.linkMessageReceivers(this)
// ...
// add the PortalFragment to the example container fragment
val fragmentManager = childFragmentManager
fragmentManager.beginTransaction().replace(R.id.example_web_app, portalFragment!!).commit()
}
/**
* Define a `dismiss` method to receive messages on the "dismiss"
* topic and act on the message. This is an example to dismiss
* a containing native DialogFragment.
*/
@PortalMethod
fun dismiss(result: String?) {
if (result != null && (result == "cancel" || result == "success")) {
this.dismiss()
}
}
@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// ...
Portal portal = PortalManager.getPortal("example");
PortalFragment portalFragment = new FadePortalFragment(portal);
// register this class as having defined message subscribers
portalFragment.linkMessageReceivers(this);
// ...
// add the PortalFragment to the example container fragment
final FragmentManager fragmentManager = getChildFragmentManager();
fragmentManager.beginTransaction().replace(R.id.example_web_app, portalFragment).commit();
}
/**
* Define a `dismiss` method to receive messages on the "dismiss"
* topic and act on the message. This is an example to dismiss
* a containing native DialogFragment.
*/
@PortalMethod
public void dismiss(String result) {
if(result != null && (result.equals("cancel") || result.equals("success"))) {
this.dismiss();
}
}
Publishing Messages
Publish messages to send data through a Portal to registered Subscribers.
From Web to iOS/Android
To send a message from your web application to iOS or Android, use the Portals.publish() function.
Portals.publish({ topic: "dismiss", data: "success" });
From Android to Web
To send messages from your native application to the web application, use the PortalsPlugin.publish()
methods.
- Kotlin
- Java
PortalsPlugin.publish("weather", "sunny")
PortalsPlugin.publish("weather", "sunny");
Examples
The PortalsPlugin
is used in the E-Commerce App demo.