Talk from RestFest on how API Chaining(tm) works in chaining multiple api calls with one request and response without redirects.

1. RestFest 2017
orubel@gmail.comOwen Rubel
API Chaining™
& API Abstraction

2. Title Text
RestFest 2017
orubel@gmail.comOwen Rubel
What is API Chaining™?
“ API Chaining is a monad allowing a series of api
calls to be passed and processed using one
REQUEST/RESPONSE.”

3. Title Text
RestFest 2017
orubel@gmail.comOwen Rubel
• Abstraction of Communication Logic/Data from Biz Logic
• Internal Redirect Handling in API Service
• Separated Communication Data from Communication Logic
Requirements for API Chaining™

4. Title Text
RestFest 2017
orubel@gmail.comOwen Rubel
Understanding API Abstraction

5. 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)

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

7. 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)

8. 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?

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

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

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

12. 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?

13. 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

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

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

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

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

18. Title Text
RestFest 2017
orubel@gmail.comOwen Rubel
Shared I/O State In Distributed Architecture

19. Title Text
RestFest 2017
orubel@gmail.comOwen Rubel
This handles the Redirect and allows
communication to take place internally when
needed…

20. 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 can 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

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

22. 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

23. Title Text
RestFest 2017
orubel@gmail.comOwen Rubel
What Does IO State Contain
•Data specifically related to I/O (request/response); not data related to
function (ie, errors, how to process, etc).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

24. 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.

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

26. 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

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

28. Title Text
RestFest 2017
orubel@gmail.comOwen Rubel
• RAML, OpenAPI, Swagger, API BluePrint
• not role based; endpoints need to be checked via token roles
• limited to CRUD-based REST of 4 calls per class
• duplicitous; lack of separation
• Confuses API data with functionality

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

30. 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
…

31. 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
…
}

32. Title Text
RestFest 2017
orubel@gmail.comOwen Rubel
This allows for new Patterns like
API Chaining™…

33. Title Text
RestFest 2017
orubel@gmail.comOwen Rubel
• Post Chain
• GET > GET > (PUT/POST/DELETE)
• Pre Chain
• (PUT/POST/DELETE) > GET > GET
• Blank Chain
• GET > GET > GET
Three types of Chains

34. Title Text
RestFest 2017
orubel@gmail.comOwen Rubel
What data is sent for a chain
API Chain Data
{
<put/post data (if applicable)>,
chain:{
key:dept_id,
combine:'false',
type:'postchain',
order:{dept/show:company_id,company/update:return}
}
}

35. Title Text
RestFest 2017
orubel@gmail.comOwen Rubel
Chain Examples
GET Chain Example
PUT Chain Example
curl -v -i -H "Content-Type: application/json" -H "Authorization: Bearer <token>" --request
PUT -d "
{'testdata':'testamundo','chain':{'key':'sectionId','combine':'false','type':'postchain','order':
{'section/get':'id','section/update':'return'}}}" "http://localhost:8080/c0.1/post/show/1"
curl -v -i -H "Content-Type: application/json" -H "Authorization: Bearer <token>" --request
GET -d "
{'chain':{'key':'Id','combine':'false','type':'blankchain','order':{'postTopic/
showByTopic':'postId','post/show':'return'}}}" "http://localhost:8080/c0.1/topic/show/1"

36. Title Text
RestFest 2017
orubel@gmail.comOwen Rubel
More documentation on API Chaining
API Chaining™ Documentation
http://orubel.github.io/Beapi-API-Framework/chain.html

37. Title Text
RestFest 2017
orubel@gmail.comOwen Rubel
DEMO

38. RestFest 2017
orubel@gmail.comOwen Rubel
Questions?
(please contact for business opportunities or hiring)