Dashboard Statistics

Background

Admin/coordinator need to see a few statistics on the experience dashboard to know if the experience is on track.

The statistics could be complex to calculate and grow to a large number. We can not just calculate everything on the fly. Instead, we pre-calculate the statistics and store the result in db, so that we can display them immediately when admin/coordinator go to the dashboard

Key logic

1. When user go to the dashboard, get the stats from the database and display them on the page.
2. At the same time, send a request to re-calculate the stats. Once the result returns, update the UI on the dashboard.
3. A cronjob runs in the background and trigger lambada function regularly.
4. The lambda function will get all the experiences that need re-calculation, and send a message to SQS Queue for each experience.
5. The lambda function listen to the SQS Queue to calculate the stats for each experience.