JSON payload formatting in IOT Protocols - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output of this JSON payload after parsing?

Given this JSON payload received from an IoT sensor:

{"temperature": 22.5, "humidity": 48, "status": "ok"}

What will be the value of the status field after parsing?

A null

B "ok"

C ok

D "OK"

💡 Hint

Remember JSON strings are enclosed in double quotes and parsing keeps string values as strings.

The status field is a string with value "ok". After parsing, it remains a string with quotes in code representation.

❓ Configuration

intermediate

Which JSON payload is correctly formatted for sending sensor data?

You want to send temperature and humidity data from a sensor in JSON format. Which of these payloads is correctly formatted?

A {temperature: 25, humidity: 60}

B {"temperature": 25, "humidity": 60}

C {"temperature": "25", "humidity": 60}

D {"temperature": 25, humidity: 60}

💡 Hint

JSON keys must be in double quotes and values can be numbers or strings.

Option B uses double quotes for keys and numeric values correctly. Option B and D miss quotes on keys. Option B uses a string for temperature which is allowed but less ideal for numeric data.

❓ Troubleshoot

advanced

Why does this JSON payload cause a parsing error?

This JSON payload is sent from a device:

{"temp": 22.5, "humidity": 55, "status": ok}

Why does it cause a parsing error?

A The commas between fields are missing.

B The temperature value 22.5 must be an integer.

C The keys temp and humidity must be numbers, not strings.

D The value ok is not in double quotes, so it's invalid JSON.

💡 Hint

In JSON, string values must be enclosed in double quotes.

The value ok is a string but is not enclosed in double quotes, causing a JSON parsing error.

🔀 Workflow

advanced

What is the correct order to process an incoming JSON payload from an IoT device?

Arrange these steps in the correct order to handle a JSON payload from an IoT sensor:
1. Validate JSON format
2. Parse JSON into data structure
3. Send acknowledgment to device
4. Extract sensor values

A 1,2,4,3

B 2,1,4,3

C 1,4,2,3

D 4,1,2,3

💡 Hint

You must check format before parsing, then extract data, then respond.

First validate the JSON format to avoid errors, then parse it, extract needed values, and finally send acknowledgment.

✅ Best Practice

expert

Which JSON payload design is best for extensibility in IoT sensor data?

You want to design a JSON payload for sensor data that may add new fields later. Which design is best?

A {"sensor_id": "123", "data": {"temp": 22.5, "humidity": 55}}

B {"sensor_id": "123", "temp": 22.5, "humidity": 55}

C [{"sensor_id": "123"}, {"temp": 22.5}, {"humidity": 55}]

D {"123": {"temp": 22.5, "humidity": 55}}

💡 Hint

Grouping sensor data inside a nested object helps add new fields without changing the main structure.

Option A groups sensor readings inside a 'data' object, making it easier to add new sensor fields later without changing the top-level keys.