Sending different push notifications to different users using Ionic 2

Question

I am completely new to push notifications, FCM and Ionic.

I have followed this tutorial to create a push notification using Ionic 2 and it works.

1. It feels like there is no use of device-id (generated at the client side) at the server side in this ionic doc.

2. I am unable to understand how to send different push notifications to different users using the same app and same server code?

3. Also whats the purpose of FCM (Server key and Sender ID) here?

4. What's the exact workflow, does it works like a web-socket?

Thanks for the guidance :)

Answer 1

1. It feels like there is no use of device-id (generated at the client side) at the server side in this ionic doc.

The device-id (aka the Registration Token) is the identifier for the specific device you intend to send the push notification to. Saving this value in your App Server is important so that you can send push notifications specifically towards it (should you decide/need to) later on.

2. I am unable to understand how to send different push notifications to different users using the same app and same server code?

As mentioned above, this is where the device-id (Registration Token) comes into play. For each device, there is a corresponding unique id, which you'll have to specify in your payload.

3. Also whats the purpose of FCM (Server key and Sender ID) here?

You can refer to the FCM docs for these:

Server Key - A server key that authorizes your app server for access to Google services, including sending messages via Firebase Cloud Messaging. You obtain the server key when you create your Firebase project. You can view it in the Cloud Messaging tab of the Firebase console Settings pane.

Important: Do not include the server key anywhere in your client code. Also, make sure to use only server keys to authorize your app server. Android, iOS, and browser keys are rejected by FCM.

Sender ID - A unique numerical value created when you create your Firebase project, available in the Cloud Messaging tab of the Firebase console Settings pane. The sender ID is used to identify each app server that can send messages to the client app.

To keep it short, Server Key is for authenticating, Sender ID is for identifying from which project the message is coming from.

4. What's the exact workflow, does it works like a web-socket?

Not really. Having a web-socket means that having the connection always active until decided to be closed, where in FCM (or even before, GCM), the lifecycle is like this:

Lifecycle Flow

• Send and receive downstream messages.

  • Send a message. The app server sends messages to the client app:
    1. The app server sends a message to GCM connection servers.
    2. The GCM connection server enqueues and stores the message if the device is offline.
    3. When the device is online, the GCM connection server sends the message to the device.
    4. On the device, the client app receives the message according to the platform-specific implementation. See your platform-specific documentation for details.
  • Receive a message. A client app receives a message from a GCM connection server.

• Send and receive upstream messages. This feature is only available if you're using the XMPP connection server.

  • Send a message. A client app sends messages to the app server:

    1. On the device, the client app sends messages to the XMPP connection server. See your platform-specific documentation for details on how a client app can send a message via XMPP.
    2. The XMPP connection server enqueues and stores the message if the server is disconnected.
    3. When the app server is re-connected, the XMPP connection server sends the message to the app server.

• Receive a message. An app server receives a message from the XMPP connection server and then does the following:

  1. Parses the message header to verify client app sender information.
  2. Sends "ack" to the XMPP connection server to acknowledge receiving the message.
  3. Optionally parses the message payload, as defined by the client app.

Answer 2

I am unable to understand how to send different push notifications to different users using the same app and same server code?

It's your task. Your message must contain all neccessary data (i.e. userId) so your app knows which of the users are target for that message.