My Dreamforce presentation on Designing custom REST and SOAP interfaces on the force.com platform covering use cases, benefits, and best practices.

1. Designing custom REST and SOAP
interfaces on Force.com
Steven Herod, Technical Director (Australia), Cloud Sherpas
@sherod

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3. Steven Herod
Technical Director, Cloud Sherpas (Australia)
@sherod
http://limitexception.herod.net/

4. Agenda
• Use cases for custom interfaces
• Upsides and downsides
• Code walkthrough
• Best Practices

5. 3 (example) use cases
• Multiple external parties need to log leads w/o duplicates
• Concern: 3rd Party needs to understand Salesforce and your data model
semantics and logic.
• Need to interact with a complex opportunity process/data model
• Concern: An internal business process with many rules needs to be
exposed to an external system.
• Your mobile app needs to modify multiple parts of the data model to
complete an action
• Concern: ‘Chatty’ network traffic, opportunity for failures at any point.

6. Benefits of going custom…
•
Transaction safety
•
•
Lower latency
•
•
Offers a narrow/specific interface that allows you to expose only the aspects of the business
logic and data model that are needed.
More Robust
•
•
Complete many activities in a single request
Service Oriented
•
•
Update multiple objects in a single request
Can unit tested.
Controlled interface
•
A published and controlled interface specific to your business.

7. Caveats
• Your ETL Tool may not understand custom REST/SOAP interfaces with
Salesforce.
•
An out of the box ‘Salesforce Adapter’ is not applicable here.
(Generic REST / SOAP should work however)
• You need to write code (and test coverage)
•
What was ‘no effort’ on the Salesforce side now becomes a Software
Development process
• Limits!
•
•
•
Request size (3MB)
SOQL query limits (100 per request)
Record modification limits(10,000 records touched)

8. For and against

9. A real life example
Public Internet user clicks this button on a Heroku
Based website or a Mobile app
Salesforce needs to do this

10. Class structure
sObjects
sObjects
sObjects
RestQuoteServiceV1
Defers to
QuoteService
DAOs
DAOs
DAOs
SoapQuoteServiceV1
Uses
Uses
QuoteModel
QuoteRequest
QuoteResponse

11. Best Practices
• Consciously design your API
• Think about it! Govern it! Consider every method/operation! Document it!
• Fight for the user
• Think: “What is easiest for the consumer of the interface?”
• Work with the platform
• Salesforce REST != REST purist
• Salesforce SOAP != WS-*
• Consider how you will manage testing with external parties
• Test data, test system availability…

12. Best Practices
• Use Apex Wrapper Classes as Data Transfer Objects
• Refrain from sending or expecting sObjects or you may expose a lot of
internal details
• Use a Services layer
• Keep your business code out of the class that handles the public interface.
• Bake in versioning
• Consider if you need to make a change to your interface
• Unit test all the things
• The unit test is your insurance and means you can detect when declarative
changes affect your code

13. Best Practices
• Manage your transactions explicitly
• Especially if you do exception trapping
• Use @future if you need to.
• Shorten response times where its safe to go async
• Indicate in the Apex Class name that is a public interface
• Consider the error feedback
• What does a API consumer see if things go wrong?
• Program defensively
• Expect bad input

14. Finally… REST specific advice
• 1 Class per URL mapping = proliferation
• Don’t forget the Query String
• E.g. GET /LoanApplications/?daysSinceUpdate=5
• Watch your status codes and verbs!
• Use the right status code and the right verb (GET, PUT, POST)
Beep