Define the local API contract
See this course’s project requirements
A localhost-only read-only JSON book API with defined routes, 200/404 responses, headers and an automated client contract test.
Keep your working files in your own notebook or software. Save a private description, checklist, and work link in My Proof.
What to include
- A three-route API contract with status and typed body.
- A loopback-only server boundary record.
- A checked json response with matching headers.
- A routing test matrix with exact-path boundaries.
- A real local transport test with bounded cleanup.
- A complete api handoff with a controlled contract change.
Review and revise
Use these criteria to check your work and choose what to improve.
- The implementation or declared simulation follows the supplied contract and retains inspectable original inputs.
- Normal, boundary and rejected cases are recorded with expected versus observed results.
- The changed case has a correct explanation and does not rely on hidden state.
- The project includes source, outputs, instructions and honest tool, privacy and verification limits.
Want more background?
The idea in everyday life
GET /books returns two book objects. GET /books/2 returns {id:2, title: River Map}. GET /books/99 returns 404 and {error: not found}.
A server contract connects method and exact path to status, headers and body. This local practice reads fictional books only. Unsupported query strings or missing IDs return 404; it is not a general production API.
Define the local API contract — original worked practice
A server contract connects method and exact path to status, headers and body. This local practice reads fictional books only. Unsupported query strings or missing IDs return 404; it is not a general production API.
GET /books returns two book objects. GET /books/2 returns {id:2, title: River Map}. GET /books/99 returns 404 and {error: not found}.
1. Step 1
Write the three exact requests.
You should see: List, existing item and missing item are separate cases.
This keeps the rule and its observable result together.
2. Step 2
Record status 200 versus 404.
You should see: A missing resource is not an empty successful object.
This keeps the rule and its observable result together.
3. Step 3
Name JSON field types.
You should see: id is number; title and error are strings; books isarray.
This keeps the rule and its observable result together.
4. Step 4
Create a request/response contract table.
You should see: A three-route API contract with status and typed body.
This keeps the rule and its observable result together.
What to finish
A three-route API contract with status and typed body.
Watch for this
Changing the resource shape between routes so the client cannot follow one declared JSON contract.
How can I tell I understand it?
Explain and demonstrate the required distinction: A server contract connects method and exact path to status, headers and body. This local practice reads fictional books only. Unsupported query strings or missing IDs return 404; it is not a general production API. Show a changed input and the expected result without weakening this contract.
Quick knowledge check
Answer all 3 questions. Get at least 2 right and the lesson completes automatically.
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Pass the check. We’ll save the progress.
Answer all 3 questions above and get at least 2 right. You can review the explanations and try again.
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Sources and further reading
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Source & access notes · checked 2026-10-01
Relevant documented module/API behavior inspected during expansion authoring; actual execution evidence is recorded separately. No grant eligibility is established.
Access: Official page retrieved with the web reader on 2026-10-01. Documentation reading does not certify execution in every native tool or browser.
Reuse: Original local practice files, fictional data, worked examples and questions. Concepts paraphrased and linked; source exercises are not copied.
Source & access notes · checked 2026-10-01
Relevant documented module/API behavior inspected during expansion authoring; actual execution evidence is recorded separately. No grant eligibility is established.
Access: Official page retrieved with the web reader on 2026-10-01. Documentation reading does not certify execution in every native tool or browser.
Reuse: Original local practice files, fictional data, worked examples and questions. Concepts paraphrased and linked; source exercises are not copied.
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