Actor lane
Contains choices or actions performed outside the software.
INTERACTIVE UML EXPLORERUSE CASE / SEQUENCE / CLASS / ACTIVITY / SWIMLANE
Teaching notes Depth
Social contentInstagram
A social content platform with publishing, communication, advertising, moderation and personalized discovery.
Individual product model with scenario-specific actors and official source notes.14functional scenarios
25available processes
25use cases in this model
125main flow actions
OVERVIEW
Platform Overview
Platform Overview models the goals, variations and supporting behaviour around the complete Instagram platform.
3 responsibility lanes7 activities3 ownership handoffs
UML SWIMLANE LAYER
Open Shared Public Post or Reel
Read downward for time and across lanes for responsibility changes.
STEP
Visitor / Guestactor
Application boundaryboundary
Domain serviceservice
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02
03
04
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OWNERSHIP CHECK
A handoff is where coordination risk appears.
Boundary lane
Accepts input and presents visible feedback.
Service lane
Applies domain rules and coordinates state.
External lane
Contains behaviour owned by a supporting system or organization.
OFFICIAL EVIDENCE AND SCOPE
What supports this model.
Public product behaviour is shown as fact. Internal services are labelled as teaching models unless the product owner documents them.
official product
Instagram Teen Accounts
Private accounts limit who can see and interact with content. This supports keeping logged-out visitors separate from registered users.
Open official source official engineeringHow AI powers Instagram experiences
Instagram uses separate ranking systems for Feed, Stories, Explore, Reels, Search, Suggested Accounts and Notifications.
Open official source course materialTeaching notes
Open the current Notion teaching pack. PDF notes can be attached here when finalized.
Open notesSYSTEM DESIGN LAYER
How this capability may be implemented.
Conceptual representation based on observable product behaviour and common large-scale architecture. Proprietary internals are not presented as fact.
Client and gateway
Receive the request and expose the public boundary.
HTTPS, API gatewayobservableCapability services
Own the platform functions selected in this overview.
service boundariesconceptualEvent pipeline
Carry completed state changes to background consumers.
event bus, queueconceptualData and analytics
Store source state and measure product behaviour.
database, object storage, warehouseconceptualKNOWLEDGE LABELS
What we know, and what we are modelling.
Visible in the product or directly testable by a user.
Described through public product or platform documentation.
A teaching model inferred from observable behaviour and common system design practice.
The proprietary implementation is not publicly known.
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Use Case
Who wants what from the system?
02
Sequence
How do participants collaborate over time?
03
Class
Which structures support the messages?
04
Activity
Which choices and parallel paths exist?
DEPTH PROGRESSION
The scenario stays fixed. The model grows.
Switch between Classroom, System Design and Near Exhaustive while keeping the same scenario selected. Actors, use cases, relationships, sequence lifelines and domain classes expand in place.