API based conditions

[jenbutongit]

related to #903

#903 runs the risk of breaking conditions, if conditions rely on an API enabled list. For example, a condition may route a user to page B if they answered "United Kingdom". If the API serving the answer "United Kingdom" has changed, or is unavailable, the condition will always fail.

API enabled lists (so far) have been suggested to be able to route a user based on another (micro service). Instead of pulling a new List on each request (and risk conditions breaking), instead we can

• POST the users' state to another API (similar to a web hook)
• the external API will then return true or false
• This answer is then "cached" until the end of the session (i.e. if the API updates mid journey, it should not affect any existing users, and the change only applies to new sessions)
• This removes risks from the XGovFormBuilder runner, and makes the runner more flexible to other use cases