Sequences
Introduction
The Invopop Sequence service makes it easy to reliably generate sequential numbers.
Most countries around the world require a sequential ID or code for business
documents like invoices to make them easier to follow. This service, solves that
problem.
Generating sequential numbers is more complex that it might seem at first
glance. For simple use-cases, a counter field inside a standard relational
database is probably sufficient, the problem however is once your project scales
and you need guarantees that requests from distributed systems will continue to
generate numbers without skips or duplication.
Our Sequence service is designed and built to be highly resilient. Behind the
scenes we use a global transaction database
(CockroachDB) to ensure data is stored
reliably, along with our own layers of queues and processes that ensure a single
process is responsible for handling any given sequence. This means our systems
can receive a high volume of requests at the same time, and still reliably
return numbers in series.
Key Concepts
The sequence service contains two key objects:- Series - the definition of a code template.
- Entry - a single “entry” in the series.