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Intro to CS 9-10 / Week 12 / Wednesday
3/6
Week 12 · Safe, Fair and Ready: Beacon Launch Review

Wednesday

Beacon Lab: The launch review
// Privacy, security, fairness and a launch day demo
⏱ about 20 min

Wednesday: Beacon Lab: The Launch Review

The whole crew gathers around the paper prototype of Beacon. Eleven weeks of notes are pinned to the wall behind it.

Comet taps her pencil on the launch checklist. "Four sections. If any item fails, we fix it before launch."

Wren lays out the screens: readings, alerts, photos and messages. "What do you notice? We have never checked all of it at once."

Nova hovers above the table and dims her light to a calm blue. "Read each item slowly," she says. "Every fix you find today is a gift to your users."

Comet takes a breath. "Section one. Security."

Your mission

You are the developer the crew relies on. Run Beacon's launch review and mark each item Pass or Fix.

For every Fix, write the change you would make. This review is the last step before launch.

  • Your Beacon notes, storyboard and pseudocode from earlier weeks, if you kept them
  • A sheet of paper for the checklist
  • A pencil and a colored pencil for fixes
  1. Copy the four section names onto your paper: Security, Privacy, Fairness, Licenses.
  2. Read each item in the review table below.
  3. Mark each item Pass or Fix in your own copy.
  4. For each Fix, write one change in colored pencil.
  5. Choose the single most important fix and circle it.
  6. Write "Reviewed by the developer" at the bottom of your paper.
SectionItemWhat the prototype does now
SecuritySign-inOne shared password: basil
SecurityUpdatesThe sensor box gets regular software updates
PrivacyCameraThe camera also catches crew walking by
PrivacySign-in fieldsAsks for age, phone number and fingerprint
FairnessAlertsAlerts are shown only as a red light, with no words
LicensesAverage libraryUses a library from another team with no credit given

This review table is invented for our story.

PASS OR FIX?
  • Read the question.
  • Tap your answer.
Sign-in: one shared password, basil.
Updates: the sensor box gets regular software updates.
Camera: it also catches crew walking by.
Alerts: only a red light, with no words.
Licenses: a library from another team, with no credit given.
PROCEDURE showAlert(plantName)
{
   DISPLAY("Alert:")
   DISPLAY(plantName)
   DISPLAY("needs water")
   lightOn("red")
}

Here is the fixed alert procedure. The words come first, and the red light is an extra signal.

In our story, lightOn comes from the sensor box's own library. Thanks to procedural abstraction, you only need to know what it does: it turns on the light named by its argument.

What the review showsTrue or false?
A launch review can find problems the team never noticed.?
An app that only watches plants can never affect privacy.?
Alerts with both words and a light work for more users.?
Using another team's code without credit is fine if it works.?
WHY THIS EXERCISEA review is where testing, privacy and fairness all meet.
What does the fixed showAlert procedure display first, words or a light? Type one word.
WHY THIS EXERCISEPutting words first makes the alert usable for more people.
On paper, sketch Beacon's alert screen after the fixes, with the alert words and the light.

Excellent review. Tomorrow you will guard Beacon against tricks and malware.

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