rxjava guide by jake wharton

“When you bow deeply to the universe, it bows back; when you call out the name of God, it echoes inside you.”
―Morihei Ueshiba

• usually do work when you start or stop listening.
• Sysnchronous or asynchronous.
• Single item, many items, or empty
  • single - network request
  • many - button click
  • empty - save file or database
• terminates with an error or succeeds to completion
• may never terminate
• just an implementation of the Observer pattern

Rxjava

• a set of classes for representing sources of data
• a set of classes for listening to data sources
• A set of methods for modifying and composing the data

Source

• Usually do work when you start or stop listening.
• Synchronous or asynchronous.
• Single item, many items, or empty.
• Terminates with an error or succeeds to completion.
• May never terminate!
• just an implementation of the Observer pattern

sources

• Observable
  
  • Emits 0 to n items
  • Terminates with complete or error.
  • Does not have backpressure.
• Flowable
  
  • Emits 0 to n items
  • Terminates with complete or error.
  • Has backpressure

Flowable vs Observable

• backpressure allows you to control how fast a source emits items.
• Rxjava 1.x added backpressure late in the design process
• All types exposed backupressure but not all sources respected it
• Backpressure, like interitance, must be designed for.

Single

• Either succeeds with an item or errors.
• No backpressure support.

Completable

• Either completes or errors. Has no items!
• No backpressure support.

Maybe

• Either succeeds with an item, completes with no items, or errors. - No backpressure support.

Flowable vs Observable

Source Specializations

• Encoding subsets of Observable into the type system
  • Single -item or error. think “scalar”
  • Completable - Complete or error, think “runnable”.
  • Maybe - Item, complete, or error. think “optional”

points ?

• create
• dispose

Operators

• Manipulate or combine data in some way
• Manipulate threading in some way.
• Manipulate emissions in some way.