Journey to understand Observer and Pub-Sub Pattern

Transcript

1. Journey to understand Observer and Pub-Sub Pattern
2. Let’s understand the need? • Derivation in a mathematical way
3. • Derive: What is observer pattern and pub sub pattern and why do we need them. • Given: iPhone, User, Different situations • Assumption: Let’s assume that there are no observers or pub sub patterns. What will happen: 1. No real time modifying view controllers:
4. 2. Periodic Monitoring increases • Regular monitoring in regular intervals • Periodic networking calls • Periodic monitoring of different resources.
5. 3. Checking the state of resources periodically
6. • Result: Nobody wants this and thus we can say we need someone to tell about the change.
7. Observer pattern & Publisher-Subscriber Pattern
8. Observer Pattern “The observer pattern is a software design pattern in which an object, called the subject maintains a list of its dependents, called observers, and notifies automatically of any state changes, usually by calling one of their methods.” -Wikipedia
9. Pub Sub Pattern • Pub: Publishers • Sub: Subscribers • A software design pattern where there are senders of some messages and they send the messages to the receivers called the subscribers. -Unknown
10. Confusing??
11. Difference in implementation Observer Pattern
12. Pub-Sub Pattern Event Channel in between called an Event Bus or Broker Pub Sub Pattern
13. APIs providing such facilities • Notification Center • Observation Protocols • RxSwift • Grand Central Dispatch • MQTT • Delegates
14. Notification Centers Posting Notifications
15. Receiving the Notification
16. Receiving the Notification
17. Receiving the Notification
18. Receiving the Notification
19. Using Protocols
20. Event Bus using RxSwift • RxSwift • Understanding of Reactive Programming • Publish Subjects
21. Publish Subjects • Subjects: Observable + Observer • It emits all the subsequent items of the source Observable at the time of subscription.
22. Use case • Event Bus to broadcast the subscribers about the events of your journey. • Beginning of journey • Ending of Journey • Journey updates • Any journey related channel
23. Steps to success!! • Create some dummy locations • Create a singleton class to set the Journey Events and get the journey events
24. Steps to success!! • Create some dummy locations • Create a singleton class to set the Journey Events and get the journey events
25. Steps to success!! • Create some dummy locations • Create a singleton class to set the Journey Events and get the journey events
26. Steps to success!! • Create some dummy locations • Create a singleton class to set the Journey Events and get the journey events
27. • Subscribe to the “Resource” in viewDidLoad( ) • Now you can get the events wherever you write this subscribe code
28. • Subscribe to the “Resource” in viewDidLoad( ) • Now you can get the events wherever you write this subscribe code
29. • Subscribe to the “Resource” in viewDidLoad( ) • Now you can get the events wherever you write this subscribe code
30. Setting the events
31. Setting the events
32. Thank You # @droid_singh amanjeetsingh150