This document discusses RESTful principles and how the Salesforce REST API implements and extends those principles. It begins by outlining Roy Fielding's definition of REST, including client-server architecture, statelessness, caching, uniform interface, layered system, and hypermedia as the engine of application state. It then demonstrates how the Salesforce REST API fulfills most of these principles through examples of retrieving and updating objects. However, it also presents two extensions - object trees and batch requests - that allow creating and manipulating multiple objects in one request, pushing the boundaries of the uniform interface principle. The document concludes by encouraging readers to carefully consider REST principles and only diverge from them when it meaningfully improves the experience.

1. All Aboard the Boxcar!
Going Beyond the Basics of REST
Pat Patterson
Developer Evangelist Architect
ppatterson@salesforce.com
@metadaddy

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3. RESTful principles
When our REST API ran out of steam
The Boxcar
Composite resources – still REST?
Agenda

4. RESTful Principles
Fielding’s Masterpiece

5. Client-Server
• Separate UI from Data Storage
• Independent evolution of components
Stateless
• Each request is self-contained
• Visibility, reliability, scalability
Cache
• Responses labeled as cacheable, or not
• Efficiency, scalability, performance
From http://www.ics.uci.edu/~fielding/pubs/dissertation/rest_arch_style.htm
Fielding’s Six Constraints

6. Uniform Interface
• Decouple implementations from services
• Trade-off: degraded efficiency
Layered System
• Each component cannot see beyond
the next layer
Code-On-Demand (optional)
• Extend client functionality via applets (!)
or scripts
Fielding’s Six Constraints

7. Identification of resources
• Resource: “any information that can be named”
Manipulation of resources through representations
• Current or intended state of resource
Self-descriptive messages
• Metadata: e.g. media type, last modified time
Hypermedia as the engine of application state
• Resource navigation via links contained in the representation
From http://www.ics.uci.edu/~fielding/pubs/dissertation/rest_arch_style.htm
Uniform Interface

8. Resources identified by URIs
• http://api.example.com/widgets/w000123
Representation by Internet media types
• JSON
HTTP with standard methods
• GET, PUT, POST, DELETE, PATCH
Hypertext links between resources
• No ‘magic knowledge’ driving interaction
REST in Practice - 2015

9. Force.com REST API Demo
Principles in Practice

10. Transactional semantics when creating hierarchies of objects?
• ‘Stateless’ REST constraint means that transaction context is tricky
Performance with high latency networks (mobile clients)
• Client framework has a message queue, wants to submit multiple
operations in a single network request
But… All Was Not Perfect in the REST API!

12. POST to /vXX.X/composite/tree/ObjectName
{
"records" :[{
"attributes" : {"type" : "Account", "referenceId" : "ref1"},
"name" : "SampleAccount",
"Contacts" : {
"records" : [{
"attributes" : {"type" : "Contact", "referenceId" : "ref2"},
"lastname" : "Smith",
"email" : smith@example.com
}, {
"attributes" : {"type" : "Contact", "referenceId" : "ref3"},
"lastname" : "Jones",
"email" : jones@example.com
}]
}
}]
}
Create whole hierarchies of related objects in a single request
Solution 1: Object Trees

13. {
"hasErrors" : false,
"results" : [{
"referenceId" : "ref1",
"id" : "001D000000K0fXOIAZ"
},{
"referenceId" : "ref2",
"id" : "001D000000K0fXPIAZ"
},{
"referenceId" : "ref3",
"id" : "003D000000QV9n2IAD"
}]
}
Object Tree Response

14. Object Tree Demo
Principles in Practice

15. ✔ Client-Server
✔ Stateless
✔ Cache
? Uniform Interface
✔ Layered System
Is This RESTful?

16. ✔ Identification of resources
✔ Manipulation of resources through representations
✔ Self-descriptive messages
✔ Hypermedia as the engine of application state
What About Uniform Interface?

17. POST to /vXX.X/composite/batch
{
"batchRequests" : [{
"method" : "PATCH",
"url" : "v34.0/sobjects/account/001D000000K0fXOIAZ",
"richInput" : {"Name" : "NewName"}
},{
"method" : "GET",
"url" : "v34.0/sobjects/account/001D000000K0fXOIAZ?fields=Name,LastModifiedDate"
}]
}
Coalesce independent requests
Solution 2: Batch Requests

18. {
"hasErrors" : false,
"results" : [{
"statusCode" : 204,
"result" : null
},{
"statusCode" : 200,
"result": {
"attributes" : {
"type" : "Account",
"url" : "/services/data/v34.0/sobjects/Account/001D000000K0fXOIAZ"
},
"Name" : "NewName",
"LastModifiedDate" : "2015-01-27T20:51:14.000+0000",
"Id" : "001D000000K0fXOIAZ"
}
}]
}
Batch Response

19. Batch Demo
Principles in Practice

20. ✔ Client-Server
✔ Stateless
✔ Cache
? Uniform Interface
✔ Layered System
Is This RESTful?

21. ✔ Identification of resources
✔ Manipulation of resources through representations
✔ Self-descriptive messages
✔ Hypermedia as the engine of application state
Straight JSON via HTTP is just one pattern, not the law!
What About Uniform Interface?

22. Go read (or reread!) Fielding’s dissertation…
at the very least, read chapter 5!
Follow the REST orthodoxy…
until it makes more sense to blaze a new trail…
and, even then, check that you’re not driving over a cliff!
Conclusion

23. Thank you