The document discusses the concept of API virtualization, highlighting its role in development and testing by simulating expected and unexpected behavior of APIs. It explains different levels of API virtualization, such as static and dynamic mocking, and provides insights on various tools and methodologies to implement API virtualization effectively. Furthermore, it outlines considerations for managing virtual APIs and when to utilize virtualization based on project complexity and dependencies.

1. API VIRTUALIZATION:
MOCKING ON STEROIDS

2. Why virtualize your
APIs?

3. Bootstrap development
Virtual API
Generate
from spec or
with tools
Client Development
Test Design
Integration Development

4. Isolate components in dev and test
Component in
dev or test
Test Execution
(automated or manual)
3rd party APIs
(virtualized)
Other APIs
(virtualized)
Legacy Systems
(virtualized)
Development
• Simulate (un)expected behavior
• Minimize impact on and usage of external systems
• Assert usage of external components

5. Enable API evolution… Corp
Corp
Web
app
Corp
App +
API
API
API
API
Device
APP
API
Device
IoT
Device
IoT
Device
API
API
API

6. Hardware /
Software
Solution
Provide Sandbox
API Virtual API
Evaluate
Integrate
Integration Test

7. Performance Testing
Solution
under test
Load Test Execution
(automated or manual)
3rd party APIs
(virtualized)
Other APIs
(virtualized)
Legacy Systems
(virtualized)
• Simulate (un)expected performance in external systems
• Minimize impact on and usage of external systems
• Triage Performance bottlenecks

8. 3 levels of API Virtualization
Static
Mocking
Dynamic
Mocking
Virtualize

9. Static and Dynamic Mocking
Static Mocking
 Static responses
– Semantically correct
– No logic
– Payloads generated from
schemas or examples
 Code or generated from metadata
 Usage: Client and Test
development
Dynamic Mocking
 Dynamic responses
– Based on input
– Re-use input in output
– Scripting
– Data-driven / Data-generation
– Simulate state
 Assertions on incoming content
 Usage: Scenario Testing,
Development

10. API Virtualization
 Runtime behavior simulation
 Runtime management
– Redirect traffic to Virtual APIs dynamically
– Access control
– Deployment
– Test execution integration
 Usage: Integration / Scenario Testing, Load
Testing, Development

11. Creation

13. Refine with dedicated tooling
 Add complex logic for request dispatching
 Add data-driven payloads
 Simulate non-functional behavior
 Add assertions for validating requests
 Pass-through to actual APIs as appropriate

14. A selection of tools
 Script / code based
– WireMock, JustMock, MockServer, etc.
 SaaS based
– Mocky.io, mockable.io, Runscope
– Part of design tools; Apiary, API Designer (Mulesoft)
 Desktop / Standalone
– Free: SoapUI (does REST too!), WireMock
– Commercial: Ready! API, Soatest, ITKO-Lisa

15. Virtualising Async APIs
 Domains
– Web: Webhooks, Async SOAP, Websockets
– Legacy: JMS, MQSeries, etc
– IoT protocols: MQTT, AMQP, XMPP, etc
 Virtualization Needs
– Simulate both sender and receiver of events
– Coordinate decoupled message flows / transactions
– Simulate both functional and non-functional behaviour
 Challenging to coordinate orchestrated components

16. Considerations
 How will virtual APIs be used and managed
– Local / Team / Enterprise
 Technical proficiency of maintainees
– Scripting / coding requirements
– Easy to create new configurations
 CI-Integration
– How redirect API calls to virtualized APIs
 Access control (internal / external)
 Reporting and Governance

17. API Virtualization – do you need it?
 Local development and basic component testing –>
Probably not
 For providing Sandbox environments -> Maybe
 Collaborative evolution and testing of APIs with low number
of controlled dependencies -> Maybe
 The same – but with high number of complex dependencies
-> Probably
 For simulating both functional and non-functional behavior in
complex distributed API-based solutions -> Definitely

18. API Virtualization – do you need it?
• Local development & basic component testing
• Requirement for sandbox environment(s)
• Collaborative evolution & testing of APIs with low number of
controlled dependencies
Maybe
• Collaborative evolution & testing of APIs with high number of
complex dependencies
Probably
• Need for simulating functional & non-functional behavior in
complex distributed solutions
Definitely

19. Thank you
 @olensmar
 ole.lensmar@smartbear.com
 @APIsUncensored / apisuncensored.io