Sergey Dolganov
Evil Martians developer, open-source enthusiast, traveller and drummer.
Making Great API Client
with Contracts
by
Dolganov Sergey @ Evil Martians
Developers
Resilient API Dependency
Request/Response
Mapping
Layer
Request/Response
Transportation
Layer
Layout
Example
Ossert:
- 4 APIs already depends
- Storage per quarter
- Non-incremental data collection
Twitter API:
- Public data for last week only
Non-Incremental
Per Quarter Storage
Layout (for Ossert)
Incremental
Per Week
Storage
twitter gem
Failed
Requests
Recovery
What If Everything Will Go Wrong?
Most Wanted Issues
-
Poor Boundaries
Output ?
Input
Sniffer
Most Wanted Issues
-
Poor Boundaries
-
Lost In Translation
Some "mutation" happens here
Idempotency
Most Wanted Issues
-
Poor Boundaries
-
Lost In Translation
-
Terminated in Action
Request
Request
Request
Request
Request
Request
Time
Switch Off
Most Wanted Issues
-
Poor Boundaries
-
Lost In Translation
-
Terminated in Action
-
Apocalypse
Developers
Resilient API Dependency
Most Wanted Issues
Murphy's Law
Design by Contracts
-
What does a contract expect?
-
What does a contract guarantee?
-
What does a contract maintain?
Most Wanted Issues
-
Poor Boundaries
-
Lost In Translation
-
Terminated in Action
-
Apocalypse
Developers
Resilient API Dependency
Design By Contracts
Most Wanted Issues
Murphy's Law
Intensity Strategy
Route
Mostly manual (only some steps are automated)
Examples:
- Export to plot.ly
Route
Mostly manual (only some steps are automated)
Solutions:
- Define expectations
- Define guarantees
- Define invariants
Automated but run manually
Examples:
-
Quarter/annual financial reports
-
CRM Contacts duplicates cleanup
Path
Path
Automated but run manually
Problems:
-
One-day Living Code Mindset
-
Shortage of Time
-
Part of the Business Domain Anyway
Path
Automated but run manually
Solutions:
-
Fail Fast
-
PORO Contracts
Road
Autonomous, usual but not frequent
Examples:
- Feedback routing to CRM
Road
Autonomous, usual but not frequent
Problems:
- Easy to loose track of issue ("not so important")
- Autonomous means could corrupt the Business Domain any time
Road
Autonomous, usual but not frequent
Solutions:
- Fail Fast (+ Errors Tracking)
- PORO Contracts
- API Calls Statistics
Highway
Autonomous, frequent
Examples:
- DHL tariff for purchase
Highway
Autonomous, frequent
Problems:
- Too Many Errors Happen
- State is Constantly Changing
- Performance Matter, Every Request Tracing Limitations
Highway
Autonomous, frequent
Solutions:
- Fail Fast (+ Errors Tracking)
- PORO Contracts
- API Calls Statistics
- API Calls Sampling
- Sampling "Hot" Switch
Developers
Resilient API Dependency
Design By Contracts
Most Wanted Issues
Murphy's Law
Intensity Strategy
Contracts Under Microscope
Contracts Test Coverage
TBD
Request/Response
Mapping
Layer
Request/Response
Transportation
Layer
Layout
Most Wanted Issues
-
Poor Boundaries
-
Lost In Translation
-
Terminated in Action
-
Apocalypse
Intensity Strategy
Design by Contracts
-
What does a contract expect?
-
What does a contract guarantee?
-
What does a contract maintain?
Thanks
Twitter: @ss_dolganov
GitHub: @sclinede
Blood Contracts: sclinede/blood_contracts
PORO Contracts: sclinede/poro_contract
Making Great API Client
By Sergey Dolganov
Making Great API Client
Nowadays, unit tests are an essential part of our development process. While we are proud we have 100% test coverage; it does not mean that our code behaves as expected, notably when we deal with external APIs. I'm working on the eBay internal project which mostly built around various API interactions: eBay API, Google Translate API, DHL API and so on. I solve different sophisticated problems based on unexpected API behavior on my daily basis. So I want to introduce a contract-based testing framework that aims to get rid of unexpected behavior of your app. I'll share the tools and approaches that will minimize the risks of being dependent on some external system API.
