Serverless computing basics in Intro to Computing - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a serverless function that returns a greeting message.

Intro to Computing

def handler(event, context):
    return [1]

Drag options to blanks, or click blank then click option'

Aevent + context

Bprint("Hello from serverless!")

Creturn "Hello from serverless!"

D"Hello from serverless!"

Attempts:

3 left

💡 Hint

Common Mistakes

Including 'return' inside the blank again causes syntax errors.

Using print instead of returning the message.

The serverless function should return a string as the output. Using return "Hello from serverless!" inside the function is correct, but since the code already has return, the blank should be just the string. So option D is correct.

2fill in blank

medium

Complete the code to extract the 'name' value from the event dictionary in a serverless function.

Intro to Computing

def handler(event, context):
    name = event[1]
    return f"Hello, {name}!"

Drag options to blanks, or click blank then click option'

A("name")

B["name"]

C.name

D{'name'}

Attempts:

3 left

💡 Hint

Common Mistakes

Using parentheses instead of square brackets.

Using dot notation which doesn't work for dictionaries.

In Python, to get a value from a dictionary, you use square brackets with the key as a string. So event["name"] is correct.

3fill in blank

hard

Fix the error in the serverless function code to correctly check if the event has a 'user' key.

Intro to Computing

def handler(event, context):
    if [1] in event:
        return "User found"
    else:
        return "User not found"

Drag options to blanks, or click blank then click option'

A'user'

Buser

C"user"

Devent['user']

Attempts:

3 left

💡 Hint

Common Mistakes

Using unquoted user causes NameError.

Using event['user'] in the condition causes a KeyError if key missing.

When checking if a key exists in a dictionary, the key must be a string in quotes. Both single and double quotes work, but since the code uses double quotes outside, single quotes inside avoid confusion. So 'user' is correct.

4fill in blank

hard

Fill both blanks to create a serverless function that returns the length of a list passed in the event under 'items'.

Intro to Computing

def handler(event, context):
    items = event[1]
    count = [2](items)
    return count

Drag options to blanks, or click blank then click option'

A["items"]

Blen

C("items")

Dcount

Attempts:

3 left

💡 Hint

Common Mistakes

Using parentheses instead of square brackets for dictionary access.

Using variable name 'count' instead of the function 'len'.

The function first extracts the list from the event dictionary using event["items"]. Then it uses the len() function to get the number of items in the list.

5fill in blank

hard

Fill all three blanks to create a serverless function that filters even numbers from a list in the event under 'numbers' and returns the filtered list.

Intro to Computing

def handler(event, context):
    numbers = event[1]
    evens = [num for num in numbers if num [2] 2 == 0]
    return [3]

Drag options to blanks, or click blank then click option'

A["numbers"]

B%

Cevens

D==

Attempts:

3 left

💡 Hint

Common Mistakes

Using parentheses instead of square brackets for dictionary access.

Using wrong operator instead of modulo '%'.

Returning the original list instead of the filtered list.

The function gets the list from the event using event["numbers"]. It then uses a list comprehension to keep numbers where num % 2 == 0 (even numbers). Finally, it returns the filtered list stored in evens.

Practice

1. What is the main advantage of serverless computing compared to traditional server management?

easy

A. You don't have to manage or maintain servers yourself.

B. You get unlimited free server usage.

C. You must buy physical servers for your code.

D. You need to install software on each server manually.

Solution

1. Step 1: Understand serverless computing basics

   Serverless computing means the cloud provider manages the servers, so you don't have to.

2. Step 2: Compare with traditional server management

   Traditional requires you to set up and maintain servers; serverless removes this burden.

3. Final Answer:

   You don't have to manage or maintain servers yourself. -> Option A

4. Quick Check:

   Serverless = No server management [OK]

Hint: Serverless means no server setup needed [OK]

Common Mistakes:

• Thinking serverless means free unlimited usage
• Confusing serverless with owning physical servers
• Assuming manual software installation is needed

2. Which of the following is the correct way to describe serverless computing?

easy

A. You run code on your own physical servers.

B. You pay only when your code runs, not for idle time.

C. You must configure the server's operating system manually.

D. You need to buy and maintain server hardware.

Solution

1. Step 1: Identify payment model in serverless

   Serverless charges you only when your code executes, not for idle server time.

2. Step 2: Eliminate incorrect options

   Options A, C, and D describe traditional server management, not serverless.

3. Final Answer:

   You pay only when your code runs, not for idle time. -> Option B

4. Quick Check:

   Serverless payment = pay per execution [OK]

Hint: Serverless billing is based on code execution time [OK]

Common Mistakes:

• Assuming you pay for server uptime even if code is idle
• Confusing serverless with owning physical servers
• Thinking manual OS setup is required

3. Consider this scenario: A serverless function is triggered by a user uploading a photo. What happens immediately after the upload?

medium

A. The serverless function runs automatically to process the photo.

B. The user must manually start the serverless function.

C. The serverless function waits until the server is manually started.

D. The photo upload fails because serverless can't handle files.

Solution

1. Step 1: Understand event-driven nature of serverless

   Serverless functions run automatically when triggered by events like file uploads.

2. Step 2: Analyze the scenario

   Uploading a photo triggers the function immediately without manual intervention.

3. Final Answer:

   The serverless function runs automatically to process the photo. -> Option A

4. Quick Check:

   Serverless = automatic event response [OK]

Hint: Serverless runs code automatically on events [OK]

Common Mistakes:

• Thinking user must start the function manually
• Assuming serverless can't handle file uploads
• Believing server must be manually started first

4. A developer wrote this serverless function code but it never runs when triggered. What is the most likely error?

medium

A. The serverless platform requires manual server start.

B. The function code has a syntax error.

C. The function is not linked to the event trigger.

D. The function runs only on physical servers.

Solution

1. Step 1: Check event trigger linkage

   Serverless functions must be connected to events to run automatically.

2. Step 2: Evaluate other options

   Syntax errors cause failures but usually error messages; manual server start is not needed; serverless does not run only on physical servers.

3. Final Answer:

   The function is not linked to the event trigger. -> Option C

4. Quick Check:

   Missing trigger linkage = no function run [OK]

Hint: Check event trigger connection if function doesn't run [OK]

Common Mistakes:

• Assuming manual server start is needed
• Ignoring event trigger setup
• Confusing serverless with physical server requirements

5. You want to build a photo-sharing app that automatically resizes images when users upload them. Which serverless feature best fits this need?

hard

A. Using physical servers to store photos only.

B. Manually starting servers to process images.

C. Paying for server uptime regardless of uploads.

D. Event-driven functions that run on each photo upload.

Solution

1. Step 1: Identify app requirement

   The app needs automatic image resizing triggered by uploads.

2. Step 2: Match with serverless features

   Event-driven functions run automatically on upload events, perfect for this task.

3. Step 3: Eliminate other options

   Manual server start and paying for uptime are not serverless advantages; physical servers only store, not process.

4. Final Answer:

   Event-driven functions that run on each photo upload. -> Option D

5. Quick Check:

   Event-driven serverless = automatic processing [OK]

Hint: Use event-driven functions for automatic tasks [OK]

Common Mistakes:

• Choosing manual server management
• Ignoring pay-per-use benefits
• Confusing storage with processing