Using the web API

Using the web API / Application building

(Rules as Code + OpenFisca) training series, session four.

OpenFisca API

Simple input/output API design

Not suitable for large scale simulations

Documentation:
http://openfisca.org/doc/openfisca-web-api/index.html

API Documentation

Supports OpenAPI specification, endpoint at '/spec', examples:

http://api.demo.openfisca.org/latest/spec

https://openfisca-aotearoa.synco.pt/spec

API and Swagger

Example:

http://legislation.demo.openfisca.org/swagger

Example API Calls

A collection of calls is explorable in the OpenFisca Aotearoa instance

https://github.com/BetterRules/openfisca-aotearoa/tree/master/openfisca_aotearoa/api_examples

Application Planning

Planning: divide inputs into:

• Computable
  - "we know their birthdate so we can compute their age"
• Already known
  - "this application is only applicable to citizens"
• User answers required
  - "we need to know how much they've earned this week"

Application cont.

Minimise the number of questions required.

• Create question logic trees
  - "we only ask their income if they have a job"
  - this is often in tension with:
• If they answer this question first we can exit
  - and/or:
• We have these 5 essential opening questions

Application cont.

How much can we inform without questions?.

• "If you earn more than $120k you are not eligible"
• "Here is a table of all the possible results"
• "We will be asking these 5 essential opening questions"

Application cont.

Mapping questions/answers to OpenFisca variables

• This question answers which inputs
  - question asking is difficult, try to match context and legal terminology
• This result for variable X can be used in variable Y
• We need this group of answers to compute this variable

Hotkeys

• f: full screen

• s: speaker notes

• b: pause

• ← / → / space: navigate through slides

• cltr / alt + click to zoom