Data compression techniques in SCADA systems - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to compress data using gzip in a SCADA system.

SCADA systems

import gzip

data = b"sensor data stream"
compressed_data = gzip.[1](data)

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

Acompress

Bdecompress

Copen

Dread

Attempts:

3 left

💡 Hint

Common Mistakes

Using decompress instead of compress

Trying to open data as a file

The gzip.compress function compresses the given data bytes.

2fill in blank

medium

Complete the code to decompress gzip data in a SCADA system.

SCADA systems

import gzip

compressed_data = b'\x1f\x8b\x08\x00'
decompressed_data = gzip.[1](compressed_data)

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

Awrite

Bopen

Ccompress

Ddecompress

Attempts:

3 left

💡 Hint

Common Mistakes

Using compress instead of decompress

Trying to open compressed data as a file

The gzip.decompress function restores compressed data to original form.

3fill in blank

hard

Fix the error in the code to correctly compress data using zlib.

SCADA systems

import zlib

data = b"control signals"
compressed = zlib.[1](data)

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

Adecompress

Bcompress

Cflush

Dopen

Attempts:

3 left

💡 Hint

Common Mistakes

Using decompress instead of compress

Using flush which is unrelated here

Use zlib.compress to compress data bytes.

4fill in blank

hard

Fill both blanks to create a dictionary comprehension that stores compressed sensor data only if size is less than 50 bytes.

SCADA systems

compressed_data = {sensor: zlib.[1](data) for sensor, data in sensors.items() if len(data) [2] 50}

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

Acompress

B>

C<

Ddecompress

Attempts:

3 left

💡 Hint

Common Mistakes

Using decompress instead of compress

Using > instead of < for filtering

Compress data with zlib.compress and filter data length less than 50 bytes.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that stores decompressed data for sensors with compressed size greater than 100 bytes.

SCADA systems

decompressed_data = {sensor: zlib.[1](data) for sensor, data in compressed_sensors.items() if len(data) [2] 100 and sensor.[3]('temp')}

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

Acompress

B>

Cstartswith

Ddecompress

Attempts:

3 left

💡 Hint

Common Mistakes

Using compress instead of decompress

Using < instead of > for length

Using wrong string method

Use zlib.decompress to restore data, filter compressed data length greater than 100, and sensors starting with 'temp'.

Practice

1. What is the main purpose of data compression in SCADA systems?

easy

A. To reduce the size of data for easier storage and faster transfer

B. To increase the size of data for better security

C. To convert data into a different format for display

D. To delete unnecessary data permanently

Solution

1. Step 1: Understand data compression purpose

   Data compression reduces the size of data to save space and speed up transfer.

2. Step 2: Apply this to SCADA systems

   In SCADA, smaller data means faster communication and less storage needed.

3. Final Answer:

   To reduce the size of data for easier storage and faster transfer -> Option A

4. Quick Check:

   Compression = smaller data size [OK]

Hint: Compression makes data smaller to save space and time [OK]

Common Mistakes:

• Confusing compression with encryption
• Thinking compression deletes data
• Believing compression changes data meaning

2. Which of the following is the correct syntax to compress data using a function named compress in a SCADA script?

easy

A. compressed_data = compress(data)

B. compressed_data = compress data

C. compressed_data <- compress(data)

D. compressed_data = compress[data]

Solution

1. Step 1: Identify correct function call syntax

   Functions are called with parentheses enclosing arguments, like compress(data).

2. Step 2: Check each option

   compressed_data = compress(data) uses correct syntax with parentheses and assignment.

3. Final Answer:

   compressed_data = compress(data) -> Option A

4. Quick Check:

   Function call syntax = parentheses [OK]

Hint: Use parentheses to call functions with arguments [OK]

Common Mistakes:

• Omitting parentheses in function calls
• Using wrong assignment operators
• Using brackets instead of parentheses

3. Given the following SCADA script snippet:

data = "sensor_reading_12345"
compressed = compress(data)
decompressed = decompress(compressed)
print(decompressed)

What will be the output?

medium

A. compressed data bytes

B. Error: decompress function not found

C. sensor_reading_12345

D. sensor_reading

Solution

1. Step 1: Understand compression and decompression

   compress() shrinks data, decompress() restores it to original form.

2. Step 2: Follow the script flow

   Data is compressed then decompressed, so print shows original data.

3. Final Answer:

   sensor_reading_12345 -> Option C

4. Quick Check:

   Decompress(compress(data)) = original data [OK]

Hint: Decompress reverses compress, output original data [OK]

Common Mistakes:

• Thinking print shows compressed bytes
• Assuming decompress changes data
• Ignoring function order

4. A SCADA script uses compressed = compress(data) but later decompressed = decompress(data) is called instead of decompress(compressed). What is the likely problem?

medium

A. Data will be compressed twice

B. Compression will fail because decompress is called too early

C. No problem, decompress can use original data

D. Decompression will fail or give wrong data because wrong variable is used

Solution

1. Step 1: Identify variable usage error

   Decompress must use compressed data, not original data variable.

2. Step 2: Understand effect of wrong variable

   Using original data in decompress causes failure or incorrect output.

3. Final Answer:

   Decompression will fail or give wrong data because wrong variable is used -> Option D

4. Quick Check:

   Decompress(compressed) needed, not decompress(data) [OK]

Hint: Always decompress the compressed variable [OK]

Common Mistakes:

• Passing original data to decompress
• Assuming decompress auto-detects input
• Mixing variable names

5. You need to compress SCADA data but want to keep it quickly accessible for real-time monitoring. Which compression technique is best?

hard

A. No compression to avoid delay

B. Lossless compression for exact data recovery

C. Lossy compression to reduce size drastically

D. Encrypt data instead of compressing

Solution

1. Step 1: Understand real-time monitoring needs

   Real-time needs exact data quickly without loss.

2. Step 2: Choose compression type

   Lossless compression keeps data exact and fast to decompress.

3. Step 3: Evaluate other options

   Lossy loses data, no compression wastes space, encryption is different.

4. Final Answer:

   Lossless compression for exact data recovery -> Option B

5. Quick Check:

   Real-time + exact data = lossless compression [OK]

Hint: Use lossless compression for exact, fast data access [OK]

Common Mistakes:

• Choosing lossy compression for critical data
• Skipping compression to save time
• Confusing encryption with compression