Api pattern

1. RestFest 2017 orubel@gmail.comOwen Rubel The New API Pattern

2. Title Text RestFest 2017 orubel@gmail.comOwen Rubel First Lets Understand The Difference Between Centralized and Distributed Architectures… Understanding The API Pattern

3. Title Text RestFest 2017 orubel@gmail.comOwen Rubel Centralized vs Distributed Architecture Centralized Architecture (Unshared I/O) Distributed Architecture (Shared I/O) microservices monolith application monolith application proxy MQapp server Client Client ClientClient (CORS,security) (caching,security)

4. Title Text RestFest 2017 orubel@gmail.comOwen Rubel • How many developers still use a centralized architecture vs a distributed architecture in their development? Centralized vs Distributed Architecture

5. Title Text RestFest 2017 orubel@gmail.comOwen Rubel • How many developers still use a centralized architecture vs a distributed architecture in their development? • How many developers used a centralized architecture for their development 5 years ago? 10 years ago? Centralized vs Distributed Architecture

6. Title Text RestFest 2017 orubel@gmail.comOwen Rubel • How many developers still use a centralized architecture vs a distributed architecture in their development? • How many developers used a centralized architecture for their development 5 years ago? 10 years ago? • Over the last 20+ years, there has been a trend toward distributed architectures due to separation of services/concerns, micro services, and Aspect Oriented Programming Centralized vs Distributed Architecture

7. Title Text RestFest 2017 orubel@gmail.comOwen Rubel “ An API is Standardized Input/Output (I/O) to/from a Separation of Concern (usually being Business Logic).” In Short : What Is An API? (1 OF 2)

8. Title Text RestFest 2017 orubel@gmail.comOwen Rubel What Is An API? (2 OF 2) owenr@uw.edu

9. Title Text RestFest 2017 orubel@gmail.comOwen Rubel “ In computer science, separation of concerns (SoC) is a design principle for separating a computer program into distinct sections, such that each section addresses a separate concern. A concern is a set of information that affects the code of a computer program” (ex HTML, CSS, JS) - Source : Separation Of Concern, Wikipedia What Is Separation of Concern? (1 of 2)

10. Title Text RestFest 2017 orubel@gmail.comOwen Rubel What Is Separation of Concern? (2 of 2) Bound Secondary Concern (Communication Logic) Primary Concern (Business Logic)

11. Title Text RestFest 2017 orubel@gmail.comOwen Rubel API Pattern in Distributed Architecture

12. Title Text RestFest 2017 orubel@gmail.comOwen Rubel API Pattern in Distributed Architecture Bound I/O Data and/or Functionality DUPLICATED I/O Data DUPLICATED I/O Data

13. Title Text RestFest 2017 orubel@gmail.comOwen Rubel API Pattern in Distributed Architecture Cross Cutting Concern

14. Title Text RestFest 2017 orubel@gmail.comOwen Rubel “Cross-cutting concerns can be directly responsible for tangling, or system inter-dependencies, within a program. Because procedural and functional language constructs consist entirely of procedure calling, there is no semantic through where two goals (the capability to be implemented and the related cross- cutting concern) can be addressed simultaneously.[3] As a result, the code addressing the cross-cutting concern must be scattered, or duplicated, across the various related locations, resulting in a loss of modularity.[2]” - Source : Cross Cutting Concern, Wikipedia What is a Cross Cutting Concern?

15. Title Text RestFest 2017 orubel@gmail.comOwen Rubel • Synchronization • Real-time constraints • Error detection and correction • Product features • Memory management • Data validation • Persistence • Transaction processing • Internationalization and localization which includes Language localisation • Information security • Caching • Logging • Monitoring • Business rules • Code mobility • Domain-speciﬁc optimizations Issues of a Cross Cutting Concern

16. Title Text RestFest 2017 orubel@gmail.comOwen Rubel This is The API Patterns Brick Wall Brick Wall

17. Title Text RestFest 2017 orubel@gmail.comOwen Rubel • API’s were created in 70’s to standardize information exchanged between services • 70’s api pattern was designed for centralized architecture; distributed architectures didn't exist. • Web API’s were based on 70’s api pattern; Roy Fielding based his work on this pre-existing pattern. • Web API’s were integrated into MVC frameworks and tools; it is now used everywhere. • JAX-RS and other tools were based on old patterns as they bind to business logic Why Did This Happen? (1 of 2)

18. Title Text RestFest 2017 orubel@gmail.comOwen Rubel • Distributed Architectures are a New Pattern. Old principles and patterns are often not re-examined unless an issue is discovered. In the case of API’s, they are a tried and true pattern and still work locally… but not ‘distributed’ • People ASSUMED the resource was the endpoint; The controller hands the resource OFF to the communication layer. The communication layer hands off I/O to other services in a distributed architecture. Hence, the communication layer is the endpoint. Why Did This Happen? (2 of 2)

19. Title Text RestFest 2017 orubel@gmail.comOwen Rubel So How Do We Fix? Title Text

20. Title Text RestFest 2017 orubel@gmail.comOwen Rubel Old API Pattern in MVC redirect/response

21. Title Text RestFest 2017 orubel@gmail.comOwen Rubel New API Pattern in MVC

22. Title Text RestFest 2017 orubel@gmail.comOwen Rubel New API Pattern In Distributed Architecture

23. Title Text RestFest 2017 orubel@gmail.comOwen Rubel This allows: • Central Piece of architecture (where REQUEST AND RESPONSE are handled) to be ‘Single Version of Truth’ (SOV) called ‘IO State’ • All services to sync data from SOV • Failure of SOV DOES NOT affect synchronization of data • Reload state on the ﬂy at SOV and update ALL subscribed services Shared IO State

24. Title Text RestFest 2017 orubel@gmail.comOwen Rubel So What Is IO State?

25. Title Text RestFest 2017 orubel@gmail.comOwen Rubel What is IO State? • Caches Communications Data • Synchronizes Architectural Props (distribute rules of communication) • Handles API Authorizations (access for communication) • Api Docs Deﬁnitions (how to communicate) I/O State is data directly related to a request/response, normally separated from functionality. Handles all data associated with communication and communication access

26. Title Text RestFest 2017 orubel@gmail.comOwen Rubel What Does IO State Contain •all the data contained in annotations act as rules associated with the URI endpoint (not URL or the FQDN) •by containing all those rules in one ﬁle and caching that data, we can share it with the other architectural components (and abstract data from functionality) •this enables us to change it on the ﬂy and reload without having to restart any services allowing subscribed services to get changes pushed to them through web hooks

27. Title Text RestFest 2017 orubel@gmail.comOwen Rubel I/O State : Communications Properties Shared I/O State is ‘IO State’ data unbound from functionality so that it can be shared across architectural components. This is the approach used by distributed architectures. Bound I/O State is ‘I/O State’ data bound to functionality which cannot be shared or synchronized with additional architectural components creating an ‘architectural cross cutting concern’. This is commonly found in centralized architectures.

28. Title Text RestFest 2017 orubel@gmail.comOwen Rubel Shared I/O State • DOESN’T bind to the application • DOESN’T bind to functionality • DOESN’T bind to a resource

29. Title Text RestFest 2017 orubel@gmail.comOwen Rubel What Does It Look Like? Title Text https://gist.github.com/orubel/7c4d0290c7b8896667a3

30. Title Text RestFest 2017 orubel@gmail.comOwen Rubel • Api Blueprint, Swagger, RAML • not role based • confuses I/O state with content/resource • based on annotations and thus not sharable in distributed architecture • duplicitous; lack of separation

31. Title Text RestFest 2017 orubel@gmail.comOwen Rubel • Dramatic Code reduction By Reducing Duplication • Automation of nearly all aspects of API • Nearly 0% downtime for changes to endpoint data and rules • New API Patterns (ie API Chaining (tm) ) What Does It Improve?

32. Title Text RestFest 2017 orubel@gmail.comOwen Rubel Code Reduction (1 of 2) Controller : Mixed Concerns (Duplication) @Secured(['ROLE_ADMIN', ‘ROLE_USER']) @RequestMapping(value="/create", method=RequestMethod.POST) @ResponseBody public ModelAndView createAddress(){ List authorities = springSecurityService.getPrincipal().getAuthorities() User user if(authorities.contains(‘ROLE_ADMIN’)){ if(params.id){ user = User.get(params.id.toLong()) }else{ render(status:HttpServletResponse.SC_BAD_REQUEST) } }else if(authorities.contains(‘ROLE_USER’)){ user = User.get(principal.id) } Address address = new Address(params) … address.user = user …

33. Title Text RestFest 2017 orubel@gmail.comOwen Rubel Code Reduction (2 of 2) Controller : Single Concern public ModelAndView createAddress(){ User user= (params.id)?User.get(params.id.toLong()): User.get(principal.id) Address address = new Address(params) address.user = user … }

34. RestFest 2017 orubel@gmail.comOwen Rubel Questions? (please contact for business opportunities or hiring) Just Open Sourced At RestFest • https://github.com/orubel/beapi_backend