148. Design a Text Sharing Service like Pastebin

The brief

Design a Text Sharing Service like Pastebin. The URL shortener with a payload: the same id generation and cache-first read path, but the value is kilobytes of text, so it moves out of the database and into object storage. Work from the scoping questions below. State assumptions for any unspecified load, guarantee or target, then trace your design end to end. Explain one difficult case and a credible alternative; the worked example is a reference, not a required implementation.

• Set the scope: How large can a text entry be and how many are created each day? Are entries public, unlisted or private?
• Define the contract: Can an entry expire or be deleted before expiry? What latency and availability must a popular entry achieve?
• Test the boundaries: Which abuse controls and ownership checks are required?

Constraints

Explicit scope and guarantees

Resolve the scoping questions for a Text Sharing Service like Pastebin. Separate stated behavior from assumptions, and identify what is outside your design.

Supported operating targets

Declare relevant volume, latency, freshness, quality or cost targets with units. Show calculations or an evaluation plan that can test them; unspecified targets are your assumptions, not hidden pass criteria.

Failure and boundary behavior

Explain how your guarantees hold in a difficult case relevant to this subject. Address: What latency and availability must a popular entry achieve? Which abuse controls and ownership checks are required?

What to cover

1. 01

   Scope and behavior contract

   Identify users, required behavior and exclusions. Answer: How large can a text entry be and how many are created each day? Are entries public, unlisted or private?

2. 02

   State and interfaces

   Define the information owned by the system and the inputs, outputs and errors at its boundaries. Resolve: Can an entry expire or be deleted before expiry? What latency and availability must a popular entry achieve?

3. 03

   Capacity and operating targets

   Estimate the dominant workload and resource demand with units and explicit assumptions. For a learned system, also state how quality is measured and what data is available.

4. 04

   Architecture and central flow

   Draw or describe the responsibilities needed for a Text Sharing Service like Pastebin. Trace a representative request, event or job from its input to a visible result; identify durable state owners.

5. 05

   Failure and boundary walkthrough

   Walk through a difficult case step by step, including detection and recovery. Consider: Which abuse controls and ownership checks are required?

6. 06

   Tradeoffs and operations

   Compare a credible alternative using your chosen workload and guarantees. Explain a remaining risk, a signal to watch and when you would change the design.

Worked designs

Explore the architecture and decisions, then build on an example with Coach.

Official design

Design a Text Sharing Service like Pastebin

The URL shortener with a payload: the same id generation and cache-first read path, but the value is kilobytes of text, so it moves out of the database and into object storage.

Explore the design

Review rubric

AI feedback uses these criteria. Scores are practice feedback.