Push notification on ios9 app

Question

My app communicates with a backend nodejs server (node, express and mongoose). I store users and messages in MongoDB.

When a user sends a new message to another one:

• I update the messages DB
• I send to the destination user a push notification

I have few questions regarding push notifications handling and performance:

• Is it a better way to have an APN server separate from my backend server (with node-pushserver for example: https://www.npmjs.com/package/node-pushserver) and request for a push notification with a REST api call from my iOS app

or

• Is it a better way to directly implement the push notification in my nodejs server when the messages MongoDB is updated (with node-apn for example: https://github.com/argon/node-apn)

I precise thay my backend server will be host by AWS soon.

If there is another solution better than above, feel free to correct me :)

Thank you for any feedback