Uploaded byAdam Culp
Hypermedia
The document discusses hypermedia and HATEOAS (Hypermedia as the Engine of Application State) as it relates to REST APIs. It defines hypermedia as a nonlinear medium including graphics, audio, video, text and hyperlinks. HATEOAS means that the client interacts with hypermedia controls exclusively, without relying on out-of-band information. The document outlines the typical REST flow and how it can be improved by following HATEOAS principles and including hypermedia links in responses to guide the client. It also discusses standards like HAL (Hypertext Application Language) and efforts in the PHP community to automate and standardize the use of HATEOAS and HAL.
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Hypermedia
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- 2. 2 Hypermedia! ● About me – DevReland Tech Lead at Nexmo – OSS Contributor – PHP-Fig member project (IBM i Toolkit) – Organizer SoFloPHP (South Florida) – Organizer SunshinePHP (Miami) – Long distance (ultra) runner – Judo Black Belt Instructor
- 3. 3 Hypermedia! ● About me – DevReland Tech Lead at Nexmo – OSS Contributor – PHP-Fig member project (IBM i Toolkit) – Organizer SoFloPHP (South Florida) – Organizer SunshinePHP (Miami) – Long distance (ultra) runner – Judo Black Belt Instructor I am the PHP Ninja!!!
- 4. 4 Hypermedia! ● Fan of iteration –Pretty much everything requires iteration to do well: ● Long distance running ● Judo ● Development ● Evading project managers ● Hypermedia!
- 5. 5 Hypermedia! ● Who avoids creatingstatic applications?
- 6. 6 Hypermedia! ● Most API clientsare static versus dynamic
- 7. 7 Hypermedia! ● What is “Hypermedia”? –"...a nonlinear medium of information that includes graphics, audio, video, plain text and hyperlinks." - wikipedia https://en.wikipedia.org/wiki/Hypermedia
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- 9. 9 Hypermedia! ● What is “Hypermedia”? "...anonlinear medium of information that includes graphics, audio, video, plain text and hyperlinks." - wikipedia It’s the WEB!
- 10. 10 Hypermedia! ● What is “Hypermedia”? Butwhat about APIs?
- 11. 11 Hypermedia! ● Typical REST Flow –Consult documentation
- 12. 12 Hypermedia! ● Typical REST Flow –Consult documentation – Make HTTP call
- 13. 13 Hypermedia! ● Typical REST Flow –Consult documentation – Make HTTP call – Get back result
- 14. 14 Hypermedia! ● Typical REST Flow –Consult documentation – Make HTTP call – Get back result – On success, hard-code for future
- 15. 15 Hypermedia! ● Typical REST Flow –Consult documentation – Make HTTP call – Get back result – On success, hard-code for future HYPERMEDIA IGNORED! HYPERMEDIA IGNORED!
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- 17. 17 Hypermedia! ● HATEOAS! – Hypermedia asthe Engine of Application State https://en.wikipedia.org/wiki/HATEOAS
- 18. 18 Hypermedia! ● HATEOAS! – Hypermedia asthe Engine of Application State – “Used as a medium and constraint for REST APIs” - wikipedia https://en.wikipedia.org/wiki/HATEOAS
- 19. 19 Hypermedia! ● HATEOAS! – Hypermedia asthe Engine of Application State – “Used as a medium and constraint for REST APIs” - wikipedia – “Client needs little to no prior knowledge about how to interact with an application...beyond a generic understanding of hypermedia.” - also wikipedia https://en.wikipedia.org/wiki/HATEOAS
- 20. 20 Hypermedia! ● HATEOAS! – Hypermedia asthe Engine of Application State – “Used as a medium and constraint for REST APIs” - wikipedia – “Client needs little to no prior knowledge about how to interact with an application...beyond a generic understanding of hypermedia.” - also wikipedia – Enables server to evolve independently https://en.wikipedia.org/wiki/HATEOAS
- 21. 21 Hypermedia! ● HATEOAS and Versioning –Enables server to evolve independently ● Versioning, what?
- 22. 22 Hypermedia! ● HATEOAS and Versioning –Enables server to evolve independently ● Versioning, what? – Websites don’t have a v1 or v2? ● Why do APIs?
- 23. 23 Hypermedia! ● The 6 PrimaryConstraints of REST – Client/Server ● Separation of concerns – Such as: ● Clients = no data storage concerns ● Servers = no concern with UI ● Allows independent evolution https://en.wikipedia.org/wiki/Representational_state_transfer
- 24. 24 Hypermedia! ● The 6 PrimaryConstraints of REST – Client/Server – Stateless ● No client context being stored on server between requests ● Each request must be independent (containing all info) ● Information of client state must stay with client https://en.wikipedia.org/wiki/Representational_state_transfer
- 25. 25 Hypermedia! ● The 6 PrimaryConstraints of REST – Client/Server – Stateless – Cacheable ● Responses must, implicitly or explicitly, define themselves as cacheable or not...to prevent client from getting stale data. https://en.wikipedia.org/wiki/Representational_state_transfer
- 26. 26 Hypermedia! ● The 6 PrimaryConstraints of REST – Client/Server – Stateless – Cacheable – Uniform Interface ● Simplifies and decouples architecture, includes: – Resource identification in request – Self-descriptive messages – HTTP verbs (GET, POST, PUT, DELETE) – HATEOAS https://en.wikipedia.org/wiki/Representational_state_transfer
- 27. 27 Hypermedia! ● The 6 PrimaryConstraints of REST – Client/Server – Stateless – Cacheable – Uniform Interface – Layered System ● Client not aware of being connected directly to server, or intermediary. – Load balancer, etc. https://en.wikipedia.org/wiki/Representational_state_transfer
- 28. 28 Hypermedia! ● The 6 PrimaryConstraints of REST – Client/Server – Stateless – Cacheable – Uniform Interface – Layered System – Code on Demand (optional, avoid) ● Servers can extend code by transferring executable code. Client side scripting. https://en.wikipedia.org/wiki/Representational_state_transfer
- 29. 29 Hypermedia! ● The 6 PrimaryConstraints of REST – Client/Server – Stateless – Cacheable – Uniform Interface – Layered System – Code on Demand https://en.wikipedia.org/wiki/Representational_state_transfer Hypermedia present in 4 of the 6
- 30. 30 Hypermedia! ● Typical REST Flow– Corrected! – Consult documentation – Make HTTP call ● GET, POST, PUT/PATCH, DELETE ● Or maybe OPTIONS call! – Get back result ● Including potential action links – Determine needs – Continue as needed
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- 32. 32 Hypermedia! ● HAL – Internet draftby Mike Kelly in 2012 ● https://tools.ietf.org/html/draft-kelly-json-hal-08 – Allows for nesting of links – Supports both JSON and XML – Incorporates documentation – Most popular
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- 36. 36 Hypermedia! ● HAL – Encourage APIsources to include HAL HATEOAS!
- 37. 37 Hypermedia! ● PHP-FIG – Hypermedia LinkDefinition Interface (PSR-13)
- 38. 38 Hypermedia! ● Automating HAL – ZendExpressive-HAL ● Works with Doctrine or many other PSR-7 compliant app ● Uses PSR-11 compliant containers ● Meets PSR-13 Hypermedia Links https://github.com/zendframework/zend-expressive-hal
- 39. 39 Hypermedia! ● See Zend Expressive-HALused on Beachcasts – Episode 7 of Expressive Series on YouTube ● https://youtu.be/dX6S-pJVUXI
- 40. 40 Hypermedia! ● Conclusion! – Use APIversioning carefully – Love Hypermedia – Learn HATEOAS – Use HAL – Automate!
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- 42. ● Thank you! – Code:https://github.com/adamculp/ Adam Culp https://beachcasts.com https://geekyboy.com https://rungeekradio.com Twitter @adamculp Questions?