Push-notifications for

Pavel Uvarov,
Software Engineer at Epam Ryazan
[e-mail]
spiderpoul
poul_uvarov

Agenda
What is PWA
How Web Push works
PWA example (Node.js, React)
Restrictions and future of PWA
QA

What is PWA?
Progressive Web Apps are web apps that use emerging web browser APIs and features along with traditional progressive enhancement strategy to bring a native app-like user experience to cross-platform web applications.

Was Steve Jobs the first to introduce the concept of PWAs?

PWAs solve customer needs
Installable - installed PWA run in a standalone window instead of a browser tab.
They're launchable from on the user's home screen.
Reliable - PWA can works offline.
Engaging - Having an icon on the home screen makes it easy to get into the app and push notifications can help alert the user of important information that requires their attention.
Responsive - should be able to adapt to different screen sizes and orientations

One app, every platform

One app, every platform
PWA are more affordable to develop and integrate than native mobile apps
PWAs do not need to be updated

Who is already using PWA?
Twitter saw a 65% increase in pages per session, 75% more Tweets, and a 20% decrease in bounce rate, all while reducing the size of their app by over 97%.
Nikkei saw 2.3 times more organic traffic, 58% more subscriptions, and 49% more daily active users.
Hulu replaced their platform-specific desktop experience with a Progressive Web App and saw a 27% increase in return visits.

PWAs leverage modern web capabilities

Progressive Web App checklist
Use a secure connection (HTTPS)
Registers a service worker
Manifest file
Cross browser support
Responsive to any screen size
Is installable
Provides an offline experience
Provides context for permission requests

Push Notifications
System level notifications, like native apps
Fresh content that engages users
Works even when page is closed
Push Notifications are assembled using two APIs: the Notifications API and the Push API.

Request permission

How Web Push works
Each browser manages push notifications through their own system, called a "push service".
This creates a special subscription object that contains the "endpoint URL" of the push service.
You send your push messages to this URL, encrypted with the public key, and the push service sends it to the right client
The endpoint URL contains a unique identifier

How Web Push works
On the client:
Subscribe to the push service
Send the subscription object to the server
On the server:
Generate the data that we want to send to the user
Encrypt the data with the user public key
Send the data to the endpoint URL with a payload of encrypted data.

The subscription object

Send a push notification

Send a push from server

What is VAPID?
Web Push Protocol not requiring strong authentication between your app and the push service
Publisher optionally identify themselves using the Voluntary Application Server Identification for Web Push (VAPID) protocol.
This provides a stable identity for the application serve

What app should do
Login/Sign in for new users
Show notification for concrete user
Should show notification on desktop and mobile simultaneously
1 hour reminder
https://hawkins-levels-tracker.now.sh/

Tech Stack
Serverless functions
Node.js
FaunaDB
CRA
TS
Auth verified by JWT
SWR
Web push
Deployed by Vercel
https://github.com/spiderpoul/hawkins-levels-tracker

CRA PWA
https://create-react-app.dev/docs/making-a-progressive-web-app/

manifest.json

Demo
https://hawkins-levels-tracker.now.sh/
Show on mobile
Notifications on both platforms
Show project, what makes it PWA, CRA service workers, manifest.json

PWA limitations
Still a new technology – all browsers don't support it fully yet
More limited hardware access
Limited performance for computation heavy operations – although WebAssembly is improving this
High battery usage

Links
https://developers.google.com/web/ilt/pwa/introduction-to-progressive-web-app-architectures
https://web-push-book.gauntface.com/
https://medium.com/progressivewebapps/history-of-progressive-web-apps-4c912533a531
https://serviceworke.rs/push-simple.html
https://web.dev/progressive-web-apps/