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REST Api with Asp Core
- 1. REST API in ASP Core Irina Scurtu .NET Technical Lead Trainer @ Scoala Informala @Fortech
- 3. AGENDA What is REST| 1 REST Constraints| 2 HTTP Status Codes| 3 HTTP Headers | 4 Richardson Maturity Model | 5 Copyright 2017 © Fortech. All rights reserved.
- 4. WHAT IS REST
- 5. REST ▪ Architectural style ▪ The architectural style of web ▪ Everything is a resource
- 9. CLIENT-SERVER ▪ We need to have a server ▪ We need to have a client ▪ The server is not aware of the client ▪ The server does data transformation under the hood ▪ The client simply uses the resources Client Server Request/Response
- 11. STATELESS ▪The server keeps no state ▪ No identifier, no trace at all ▪If there is a trace, it’s contained in the request ▪ Eg: authentication details ▪The server treats each request as a new one
- 12. CACHE ▪The most important spec of the HTTP ▪The server must mark the response as cacheable or not cacheable ▪It may increase the perceived performance ▪It may save database roundrips especially if the data doesn’t change often ▪Done through headers
- 13. LAYERED SYSTEM ▪ The client can talk with an intermediate ▪ It only receives the resource ▪ It doesn’t matter if there is a load balancer involved or a proxy, or a gateway
- 14. UNIFORM RESOURCE ▪Everything is a resource ▪A resource is anything that can be named ▪Every resource must have an URL ▪ Any document that can be read on the client, is a representation of a resource ▪ Has 4 subconstraints
- 15. 1.IDENTIFICATION OF RESOURCES ▪A resource needs to be addressable ▪A resource doesn’t correspond to a database table ▪It can be a subset, or a transformed entity
- 17. 1.IDENTIFICATION OF RESOURCES ▪ /getLocation ▪ /newCat ▪ /feedCat ▪ /getAllCats ▪ /getBlackCats ▪ /getHungerLevel ▪ /getCatOwners BAD!!!! Hard to remember!
- 18. 2.MANIPULATION OF RESOURCES THROUGH REPRESENTATIONS ▪A client doesn’t interact with the domain objects ▪It doesn’t query the database directly ▪It sends a representation of a resource to be updated
- 19. 3.SELF-DESCRIPTIVE MESSAGES ▪Each request/response includes details and meaning ▪Each request/response must be able to be understood in isolation ▪Add meaning through:
- 22. 4.HATEOAS ▪Hypermedia as engine of application state ▪ We should use the links( hypermedia with text) to navigate the app ▪ A response should include a links section that allows the hierarchical navigation { "links": { {“rel": “self” , "href": "/superheroes" }, {“rel”: "next“, "href": "/superheroes?page=2" } } }
- 23. 4.HATEOAS Superheroes?page=2 superheroes superheroes/3 superheroes/3/friends Superheroes/3/friends/2
- 26. 2 URLs for each resource A collection /superheroes/getAll vs /superheroes An element /superheroes/getSuperhero?id=1 vs /superheroes/1
- 27. Guidelines ▪ Cool URIs don't change ▪ Use nouns not verbs ▪ Plural not singular ▪ Concrete /things vs /dogs ▪ Variations - > query strings - not different endpoints
- 28. Status Codes
- 29. OK ?! 200 Or When OK really means OK
- 30. 201
- 31. 202 - Accepted - For further processing - For enqueuing something
- 32. 204 – No content - After deleting a resource
- 33. 401
- 34. 403 - Identified but not allowed to perform an operation Inapropriate picture
- 35. 404
- 36. 405 – Not Allowed
- 37. 406 – Not Acceptable - Accept header – xml - Server does only json Server Client Sends only xml Knows to read only json
- 38. 409
- 39. 415 Accept header has a media type you don’t support
- 40. Header fields A suuuuuper small list
- 41. Accept ▪ The mime type the client prefers and understands Accept : text/xml Accept : application/json
- 42. Content-Type ▪ The mime type of the request body ▪ Describes the content of the request Content-Type : text/xml
- 43. Location ▪ After a non-idempotent operation
- 46. Level 0 ▪ YOU KNOW how to use it ▪ Single endpoint • Go to a restaurant and order pizza, curry and Chinese The food is good?
- 47. Level 1 ▪ One verb - different locations • Go to the italian restaurant to order pizza • Go to the Chinese restaurant to order Chinese food • Go to the Indian restaurant to order curry
- 48. Level 2 ▪Uses Http Verbs and multiple resource endpoints • Order a pizza from Italian restaurant • After 5 minutes change the order to add extra mozzarella
- 49. Level 3 ▪Http Verbs and multiple resource endpoints + options • Order a pizza • Get the pizza • Waiter gives info about the available toppings for the pizza • Informs you that they have other pizza types
- 50. RMM HTTP verbs+ URI + Hypermedia = HATEOAS HTTP verbs + multiple URI single verb +multiple URI One Verb + one URI
- 51. WHY - Benefits ▪ ? ▪ ? ▪ ? ▪ ?
- 52. THANK YOU
- 53. Q&A