Designing custom REST and SOAP interfaces on Force.comDesigning custom REST and SOAP interfaces on Force.com

Steven Herod, Technical Director (Australia), Cloud Sherpas

@sherod

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Steven HerodSteven Herod

Technical Director, Cloud Sherpas (Australia)

@sherod

http://limitexception.herod.net/

Technical Director, Cloud Sherpas (Australia)

@sherod

http://limitexception.herod.net/

Agenda

• Use cases for custom interfaces

• Upsides and downsides

• Code walkthrough

• Best Practices

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.

Benefits of going custom…• Transaction safety

• Update multiple objects in a single request

• Lower latency• Complete many activities in a single request

• Service Oriented • 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• Can unit tested.

• Controlled interface• A published and controlled interface specific to your business.

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)

For and against

A real life examplePublic Internet user clicks this button on a HerokuBased website or a Mobile app

Salesforce needs to do this

Class structure

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…

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

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

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