API design principles for accelerated development

One of the largest issues in API architecture development is that the task is often driven by the pragmatic indoctrination of a specification into a product rather than designing around the speed and ease of development, usually due to a separation between the engineering teams and their core developer user base. Extending upon the ideas of API design around developer accelerated development, we will take a deeper look into some of the great techniques delivered to us through the RESTful specification, applying them to developer API consumption practices with the intention of creating efficient best practices for rapid development. Within this talk we will explore what we have learned through reconstructing our API backbone at PayPal for our developer community, including: - API automation practices for code reduction and application longevity - Open security standards that promote developer integration ease and maintain strict security practices - RESTful API architecture best practices for developer centric accelerated development

Transcript

1. API Design Principles For Accelerated Development Jonathan LeBlanc (@jcleblanc) Head of Developer Evangelism PayPal North America
2. The Exploration of API Design Blank Slate   Constraints  
3. Building APIs for Developers
4. The Tradeoff Decision
5. Developer efficiency task 1 Lowering perceived latency for developers Lower Perceived Latency
6. What’s the Tradeoff? System Layering Result Caching
7. Layering the System Encapsulates legacy systems Simplified components Better load balancing abilities Systems can evolve independently
8. Separation of Concerns
9. Stateless System Latency Issues Data Duplication   A + B   A + C  
10. Caching for Latency Reduction
11. Developer efficiency task 2 Use HTTP properly – standard request and response types Not Hindering with HTTP
12. What’s the Tradeoff?
13. Requests and Responses GET / PUT / POST / DELETE have specific actions Proper status codes and error responses
14. Don’t do This {"error": "error 10008"} Do This HTTP/1.1 400 Bad Request Content-Length: 35 {"message":"Problems parsing JSON"} Descriptive Messaging
15. X-Rate-Limit-Limit Number of requests allowed in current period X-Rate-Limit-Remaining Number of remaining requests in current period X-Rate-Limit-Reset Number of seconds left in current period Useful Responses on Rate Limiting
16. Use Status Cats! http://httpcats.herokuapp.com/ Don’t Want to Use Boring Responses?
17. Allowing HTTP Overriding curl -i -X POST https://api.sandbox.paypal.com/v1/ payments/ \ -H "Content-Type:application/json" \ -H "X-HTTP-Method-Override: PUT" Injecting PUT / DELETE methods when HTTP client only supports GET / POST
18. Action Automation
19. What’s the Tradeoff? Payload Size   Code Length  
20. RESTful API Core Concepts Honor HTTP request verbs Use proper HTTP status codes No version numbering in URIs Return format via HTTP Accept header Double Rainbow: Discovery via HATEOAS
21. To Version or Not to Version
22. Uniform Interface Sub-Constraints Resource Identification Resources must be manipulated via representations Self descriptive messages Hypermedia as the engine of application state
23. How we Normally Consume APIs
24. Using HATEOAS to Automate
25. How HATEOAS Works curl -v -X GET https://api.sandbox.paypal.com/v1/ payments/authorization/2DC87612EK520411B \ -H "Content-Type:application/json" \ -H "Authorization:Bearer ENxom5Fof1KqAffEsXtx1HTEK__KVdIsaCYF8C" You make an API request  
26. "links": [ { "href":"https://api.sandbox.paypal.com/v1/payments/ authorization/6H149011U8307001M", "rel":"self", "method":"GET" },{ "href":"https://api.sandbox.paypal.com/v1/payments/ authorization/6H149011U8307001M/capture", "rel":"capture", "method":"POST" },{ "href":"https://api.sandbox.paypal.com/v1/payments/ authorization/6H149011U8307001M/void", "rel":"void", "method":"POST" } ]
27. Developer efficiency task 2 Secure Data Resources
28. What’s the Tradeoff? Security   Usability  
29. Some Security Models Proprietary Solution Basic Authentication OAuth 1.0a OAuth 2 / OpenID Connect Cross-Origin Resource Sharing (CORS)
30. Keeping Things Hidden Token based auth mechanism OAuth: Client Secret Basic Auth: Password API request action to reaction mapping A schematic for how data forces site changes  
31. A Modern Approach CORS Client-side SDK OpenID Connect Server-side SDKs
32. Working on the Server Side SDKs Secure Token Management Separation of Concerns Simplified Development
33. Cross Origin Issues and Options Access to other domains / subdomains is restricted (same origin policy) JSONP to request resources across domains Only supports HTTP GET requests Cross-origin resource sharing (CORS) Supports additional range of HTTP requests
34. Can you use it? http://caniuse.com/cors  
35. How Does it Work? OPTIONS /v1/oauth2/token HTTP/1.1 Origin: http://jcleblanc.com Access-Control-Request-Method: PUT Access-Control-Request-Headers: X-Custom-Header Host: api.sandbox.paypal.com Accept-Language: en-US Connection: keep-alive ... Site sends Origin header to server  
36. How Does it Work? Server responds with matching Access-Control-Allow-Origin header   Access-Control-Allow-Origin: http://jcleblanc.com Access-Control-Allow-Methods: GET, POST, PUT Access-Control-Allow-Headers: X-Custom-Header Content-Type: text/html; charset=utf-8
37. Developer efficiency task 4 Offload complexity to the implementing provider Offload Complexity
38. The Complexities Authentication / Authorization Legacy API support Working between versioning API changes that break implementations Reduction in latency
39. GET /payment POST /sale POST /payment DELETE /refund GET /getSinglePayment POST /setNewSingleSale POST /addNewSinglePayment DELETE /issueSingleRefund URL Structure, Verbs, and Nouns
40. Representations on Update / Create { "id": "PAY-17S8410768582940NKEE66EQ", "create_time": "2013-01-31T04:12:02Z", "update_time": "2013-01-31T04:12:04Z", "state": "approved", "intent": "sale", "payer": {...}, "transactions": [{...}], "links": [{...}] } Send enough detail to not have to make another request to the API  
41. API architecture is all about tradeoffs You are not making a perfect system, you are making a perfect system for your developers Bringing it all Together
42. Thanks! Questions? http://slideshare.net/jcleblanc Jonathan LeBlanc (@jcleblanc) Head of Developer Evangelism (NA)