Python Event Stream Processing Service | Dataford Interview Questions

Write a fully functioning Python service from scratch, including comprehensive unit tests, to process a stream of incoming event records for Vendelux. Implement the required behavior as a pure function that validates records, rejects malformed or duplicate events, and aggregates accepted events by type. Input is a list of dictionaries with event_id, event_type, timestamp, and payload; return accepted IDs, indexed rejection reasons, counts by type, and the latest timestamp by type.

Constraints

0 <= len(events) <= 100000
Each valid event contains event_id, event_type, timestamp, and payload
event_id and event_type are non-empty strings
timestamp is an integer and payload is a dictionary
Only the first valid occurrence of an event_id is accepted
The function must process records in a single left-to-right pass

Function Signature

def process_event_stream(events):

Your question is Python Event Stream Processing Service. Start with the requirements in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.

Problem

Constraints

0 <= len(events) <= 100000
Each valid event contains event_id, event_type, timestamp, and payload
event_id and event_type are non-empty strings
timestamp is an integer and payload is a dictionary
Only the first valid occurrence of an event_id is accepted
The function must process records in a single left-to-right pass

Function Signature

def process_event_stream(events):

Your question is Python Event Stream Processing Service. Start with the requirements in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.