At Unless, global performance is guaranteed in the following way.
The script and component data
Integrating Unless with your product or website is efficient with our optimized snippet. This snippet loads the required script and associated component data asynchronously, causing it not to block your web page. Our snippet is designed for optimization to guarantee all assets will be there when you need them. Over 99.8% of our customer's websites show that the snippet loads faster than it takes for the web page to process.
Our rapid component swapping is possible since we solely store the smallest pieces of data – the "delta." Specifically, we store the difference between the original page and the page featuring the Unless components, including its location, reference to a component, and personalized content. This approach is akin to Google Docs where multiple users can collaborate on a single document simultaneously by exchanging small deltas between them. To supercharge our method, we utilize the same technology for our integration.
The Unless script and information are directly served as flat files stored on Amazon's S3 file storage service, cached, and dispersed from the Cloudfront CDN. CloudFront's global network comprises 150 Points of Presence (139 Edge Locations and 11 Regional Edge Caches) in 65 cities across 29 countries, providing reliable and rapid service that is almost impossible to break since we refrain from using any running code.
The dynamic part of the system that returns audience memberships is based on the AWS API Gateway. All code is executed using serverless Lambda functions (which execute in parallel automatically for each request). The system is currently entirely duplicated across three regions: Europe, US East and US West.
All live data is stored in AWS DynamoDb (the giant non-relational database service that we share with Twitter, Netflix and Amazon itself). DynamoDB is configured to use Global Tables in the same regions as the system itself, as a multi-region, multi-master database.
This gives us a very consistent performance across the world.
Extending the system even further
It would be easy to extend our current API endpoints with duplicates in South America, Canada, China or other parts of Asia as well, but so far this hasn’t been necessary. Let us know if you think otherwise.
A note on privacy
Only the data that is required to serve components is duplicated across the world. The Redshift cluster for data warehousing - that contains historical data for analysis and dashboard purposes - is housed in Europe only, to take into account privacy laws.