1. Reactive Android Development
CS T & CS T
Summer 2016

2. The Reactive Part

3. Definition: Reactive Any program that responds to input in real time
GUIs
Embedded systems
Contrast with 'batch' processing
E.g. compiler
This isn't anything new!!

4. FRP Functional Reactive Programming Born out of Haskell
No Side Effects -> No GUIs

5. Sodium FRP
A Java implementation of the basic philosophy of FRP as originally defined by Conal Elliot
guarantees "glitch freedom"
is currently single threaded
arguably a competitor to the Observer Pattern.

6. Reactive Extensions Born from Microsoft's LINQ
A 'Halfway' point between functional and imperative
does not guarantee "glitch freedom"
is multi-threaded
It has been presented as a cleaner syntax for the observer pattern

7. The Android Part
TracFone LG Lucky No Contract Phone

8. A collection of components
Activities
One per screen in the app
Services
Run in the background
Content Providers
Manages shared app data
Broadcast Receivers
Handle messages from the system

9. Manifest
XML file that describes all of the components that your app provides
Lists the user permissions that your app requires
It's best to ask for only those that you need
Defines the minimum hardware and software versions required by the app.
Etc.

10. Activities The logic behind the user-interface elements of the app
Only run when in the foreground
Can be instantiated by a different app!

11. Services Run in the background
Even behind other apps!
Should only be used if you wish for it to run in the background of other apps.
Use threads for most blocking actions (I/O, computation, etc.)
Can be instantiated by other apps!

12. Broadcast Receivers
Receives notifications from other parts of the Android system
Or even other apps
Generally does very little work
E.g. Activates a service to do the real processing.

13. Content Providers Generally used to manage data shared by many apps
E.g. The user's list of contacts
Can also be used to store data that is private to the application

14. Intents All app components are produced in response to an Intent.
Two types
Explicit
Specifies a particular component to start by name
Implicit
Specifies a general action, but one of any number of components might fulfill it
If several components can match an Intent, the user is prompted to specify which should be used.

15. Intent Filters Part of the manifest entry for each component
Used to advertise the services that a component can provide.
Broadcast Receivers can have dynamic intent filters
But all intent filters must be listed in the manifest

16. Activity Lifecycle

17. Resources Stored in the 'res' directory
Simplifies internationalization and support for multiple devices
The 'R' class
Automatically generated
Provides access to resources defined in the 'res' directory