the-algorithm/pushservice/readme.md

45 lines
2.2 KiB
Markdown
Raw Normal View History

# Pushservice
Pushservice is the main push recommendation service at Twitter used to generate recommendation-based notifications for users. It currently powers two functionalities:
- RefreshForPushHandler: This handler determines whether to send a recommendation push to a user based on their ID. It generates the best push recommendation item and coordinates with downstream services to deliver it
- SendHandler: This handler determines and manage whether send the push to users based on the given target user details and the provided push recommendation item
## Overview
### RefreshForPushHandler
RefreshForPushHandler follows these steps:
- Building Target and checking eligibility
- Builds a target user object based on the given user ID
- Performs target-level filterings to determine if the target is eligible for a recommendation push
- Fetch Candidates
- Retrieves a list of potential candidates for the push by querying various candidate sources using the target
- Candidate Hydration
- Hydrates the candidate details with batch calls to different downstream services.
- Pre-rank Filtering, also called Light Filtering
- Filters the hydrated candidates with lightweight RPC calls.
- Rank
- Perform feature hydration for candidates and target user
- Performs light ranking on candidates
- Performs heavy ranking on candidates
- Take Step, also called Heavy Filtering
- Takes the top-ranked candidates one by one and applies heavy filtering until one candidate passes all filter steps
- Send
- Calls the appropriate downstream service to deliver the eligible candidate as a push and in-app notification to the target user
### SendHandler
SendHandler follows these steps:
- Building Target
- Builds a target user object based on the given user ID
- Candidate Hydration
- Hydrates the candidate details with batch calls to different downstream services.
- Feature Hydration
- Perform feature hydration for candidates and target user
- Take Step, also called Heavy Filtering
- Perform filterings and validation checking for the given candidate
- Send
- Calls the appropriate downstream service to deliver the given candidate as a push and/or in-app notification to the target user