Asynchronous programming in Scala

The presentation show the basic introductory concept of asynchronous programming, a programming model that allow application scalability and high performance across distributed systems.

Transcript

1. Nairobi JVM MeetUp Asynchronous Programming in Scala @_binkabir I never lose. I either win or learn – Nelson Mandela Nigerian name: Idris Muhammad Kabir Kenyan Name: Kamau
2. Synchronous programming •  Blocking •  Logic is expressed as a sequence of steps. •  Calling a method which adds two number looks the same as calling a method which does I/O e.g http request, DB operations.
3. Challenges with Synchronous? •  Code written in a blocking fashion doesn’t scale •  Each Business logic requires a threads and threads are expensive resources. Hence, synchronous quickly reach the thread limits
4. Synchronous execution Dinner is Ready Task 1 Task 2 Task 3
5. Why Asynchronous •  Runs on Less Thread(Business logic are interleaved) •  Efficient Utilization of OS-level thread •  Performance
6. Asynchronous programming •  Synchronous execution •  Asynchronous execution – Single-threaded asynchronous execution – Multi-threaded asynchronous execution
7. Single-threaded asynchronous execution Dinner is Ready Task 1 Task 2 Task 3
8. Multi-threaded asynchronous execution Dinner is Ready Task 1 Task 2 Task 3
9. Styles of Asynchronous Code •  Callbacks - Asynchronous methods accepts an additional callback parameter •  Wrappers( Containers) - objects that represent an asynchronous operation e.g Future, Task or IO
10. •  The ability to grab a computation’s results and treat is a value make wrappers preferred option •  Parallel data processing (multiple I/O operations) •  Side effects are contained and I/O is clearly demarcated
11. Asynchronous Object in Scala Futures provide a way to reason about performing many operations in parallel– in an efficient and non-blocking way. A Future is a placeholder object for a value that may not yet exist Return 2 possible values •  Value => Success •  Exception => Failure
12. •  Asynchronous computations that field futures are created with Future.apply call and are computed using a supplied ExecutionContext, which can be backed by a Thread pool.
14. •  Future callbacks have not guaranty in the order of execution.
15. Map - method
16. For comprehension
17. andThen - method These Future callbacks are executed in the order of declaration
18. Recover - Method •  Creates a new future that will handle any matching throwable that this future might contain. If there is no match.
19. recoverWith - method Creates a new future that will handle any matching throwable that this future might contain by assigning it a value of another future.
20. Other Libraries •  Cats IO •  Scalaz Task •  Monix Task
21. Demo Time •  Consider a task of writing an application that gets a gets yours gravatar then look up same user’s github profile asynchronously.
22. Questions