Communicating with Android devices

Who am I

• Sr. Software Developer At RedHat
• Georgia Native
• Ajug Emeritus 
• RHMAP Community Liaison (Jan 1)

About This Talk

• How to get data to Android Devices
  • Slight bias toward stock Android APIs
• On Demand Refresh
  • Loaders, AsyncTask, Services
• Doing Polling Right
  • It has a bad reputation
• FCM with RHMAP
  • If you can use FCM use FCM
• Other Options for Real Time
  • Socket and event based

Data on Demand

• Refresh data from a server
• One option for older systems
• Gives uses controls

Data on Demand

AsyncTask

• Gets Network access off the main task
• Good for one shot options
• Interacts badly with the activity lifecycle

Data on Demand

Loaders

• Gets Network access off the main thread
• Tightly coupled with Activity lifecycle
• More nuanced than Async Task

Data on Demand

Services

• Gets Network access off the main Activity
• No coupling with Activity Lifecycle
• More exposure to Android system

Data on Demand

• Cat Facts Demo
• https://github.com/secondsun/CatFacts

Polling

• The device will connect to a remote server on a schedule
• Bad for battery, often unnecessary
• Lots of cases to handle
• Lots of libraries to help

Polling

Job Scheduler

• Android 21 API
• Schedules all periodic tasks based on their needs
  • Networking
  • Power
  • etc
• Compatibility API in Firebase
  • JobDispatcher

Polling

Other Options

• Roll your own
  • ​Be aware of battery
  • Be aware of back-off
  • Don't overload server
  • Handle retries
  • Reschedule around network/power availability
  • Won't cooperate across apps
• Evernote
  • https://github.com/evernote/android-job

Polling

Other Options

• Hijack AlarmManager
  • Google's engineers say just use Firebase instead
• Hijack SyncAdapters
  • May be better if you need deeper integration with Android
  • Has great integration with Android Authentication system
  • Really complex

Polling

• Demo - Weather Poller
• https://github.com/secondsun/PollingDemo

Push Notifications

• Server notifies devices when data changes
• Asynchronous messaging via Google's services
  • Firebase Cloud Messaging
• These messages may send up to 4k of data
• If data is too large, use push to sync
  • Schedule a job with the JobScheduler

Push Notifications

• If you can't use Google Play Services...
• Amazon Kindle Devices have their own protocol
• Requires Server support
  • Older servers may need updates
  • May need to write bridges to connect to legacy servers

Push Notifications

• Demo!
• Github Star Notifications

Other Options

• For all the other ways to get data to your device

Other Options

• Don't
• If your app is brochure-ware just ship it
  • Cordova can help by packaging a static website into a apk

Other Options

• [Web|BSD]Sockets
• BSD Sockets work just like they do in Java SE
  • Might need ports open in firewalls
  • Might not work with VPS
• WebSocket libraries vary in quality and features
  • Works over HTTP
  • Easy SSL
  • Works in browsers / cross platform
  • Netty Demo