Media sharing in messages in HLD - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Architecture

intermediate

Design components for media sharing in messaging

Which component is most essential to handle media file uploads in a scalable messaging system?

A A media storage service that stores files and provides URLs

B A message queue to deliver text messages only

C A notification service that sends alerts without storing media

D A user authentication module without media handling

💡 Hint

Think about where the media files themselves are kept and accessed.

The media storage service is critical to store and serve media files efficiently. Other components support messaging but do not handle media storage.

❓ scaling

intermediate

Scaling media delivery in messaging apps

What is the best approach to efficiently deliver large media files to many users in a messaging app?

A Send media files directly from the sender's device to each recipient

B Store media files only on the messaging server without caching

C Use a Content Delivery Network (CDN) to cache and serve media files globally

D Compress media files on the client side and send as text messages

💡 Hint

Consider how to reduce latency and server load when many users access the same media.

A CDN caches media files close to users, reducing latency and server load. Direct sending or no caching causes delays and high load.

❓ tradeoff

advanced

Tradeoffs in media storage formats

Which storage format tradeoff is most important when designing media sharing for messages?

A Choosing between SQL and NoSQL for user profile data

B Choosing between storing media as blobs in a database or as files in object storage

C Choosing between synchronous and asynchronous message delivery

D Choosing between storing user passwords as plain text or hashed

💡 Hint

Focus on how media files are stored and accessed efficiently.

Storing media as blobs in databases can cause performance issues; object storage is optimized for large files and scalability.

🧠 Conceptual

advanced

Handling media metadata in messaging systems

What is the primary reason to store metadata (like file type, size, thumbnail) separately from media files?

A To allow users to edit media files directly in the database

B To reduce the total storage space used by media files

C To encrypt media files separately from metadata

D To enable quick access and filtering without loading large media files

💡 Hint

Think about how apps show previews or lists of media without downloading full files.

Metadata allows the system to quickly show information and previews without loading large files, improving performance and user experience.

❓ estimation

expert

Estimating storage needs for media sharing

A messaging app expects 1 million users sharing an average of 5 media files per day. Each file averages 3 MB. What is the approximate monthly storage requirement in terabytes (TB)?

A 450 TB

B 15 TB

C 900 TB

D 150 TB

💡 Hint

Calculate total daily data, then multiply by 30 days, convert MB to TB (1 TB = 1,000,000 MB).

Daily data = 1,000,000 users * 5 files * 3 MB = 15,000,000 MB = 15 TB/day. Monthly = 15 TB * 30 = 450 TB (option A).

Practice

1. What is the main reason to separate media storage from message text storage in a messaging system?

easy

A. To reduce the number of messages sent

B. To make the user interface more colorful

C. To improve performance and scalability by handling large media files separately

D. To avoid using cloud storage services

Solution

1. Step 1: Understand media file size impact

   Media files like photos and videos are large and can slow down message storage if kept together.

2. Step 2: Separate storage benefits

   Separating media storage allows using specialized systems like CDNs and cloud storage optimized for large files.

3. Final Answer:

   To improve performance and scalability by handling large media files separately -> Option C

4. Quick Check:

   Separate media storage = better performance [OK]

Hint: Separate big files from text for faster message handling [OK]

Common Mistakes:

• Thinking media size doesn't affect performance
• Confusing UI design with storage design
• Ignoring scalability needs

2. Which component is essential for efficiently delivering media files in a messaging system?

easy

A. Content Delivery Network (CDN)

B. Message queue

C. Load balancer for text messages

D. Database index

Solution

1. Step 1: Identify media delivery needs

   Media files are large and need fast delivery to users worldwide.

2. Step 2: Role of CDN

   A CDN caches media files close to users, reducing latency and bandwidth usage.

3. Final Answer:

   Content Delivery Network (CDN) -> Option A

4. Quick Check:

   Fast media delivery = CDN [OK]

Hint: Use CDN to speed up media file delivery [OK]

Common Mistakes:

• Confusing CDN with database indexing
• Thinking load balancers handle media files
• Ignoring network latency

3. Given a messaging system where media files are uploaded to cloud storage and messages store only media URLs, what is the expected behavior when a user sends a photo?

medium

A. The photo is embedded directly in the message text stored in the database

B. The photo is uploaded to cloud storage and the message stores a URL pointing to it

C. The photo is sent as a base64 string inside the message

D. The photo is stored in the message queue before delivery

Solution

1. Step 1: Understand media upload flow

   Media files are large, so they are uploaded separately to cloud storage for efficiency.

2. Step 2: Message stores media reference

   The message contains a URL pointing to the media location, not the media itself.

3. Final Answer:

   The photo is uploaded to cloud storage and the message stores a URL pointing to it -> Option B

4. Quick Check:

   Media URL in message = cloud upload [OK]

Hint: Messages store URLs, not media files directly [OK]

Common Mistakes:

• Embedding large media in message text
• Using base64 which increases size
• Storing media in message queues

4. A messaging system stores media files directly in the message database causing slow queries. What is the best fix?

medium

A. Increase database RAM without changing design

B. Delete all media files from messages

C. Compress media files and keep them in the database

D. Move media files to cloud storage and store only URLs in the database

Solution

1. Step 1: Identify problem with current design

   Storing large media in the database slows down queries and reduces scalability.

2. Step 2: Apply best practice for media storage

   Moving media to cloud storage and storing URLs improves performance and scalability.

3. Final Answer:

   Move media files to cloud storage and store only URLs in the database -> Option D

4. Quick Check:

   Separate media storage = faster queries [OK]

Hint: Store URLs, not media, in message DB for speed [OK]

Common Mistakes:

• Relying only on hardware upgrades
• Compressing media but still storing in DB
• Removing media reduces feature, not fix

5. You design a messaging app that supports sharing photos and videos. To handle millions of users, which combination of components best ensures scalability and fast media delivery?

hard

A. Upload media to cloud storage, use a CDN for delivery, and store media URLs in messages

B. Store media in the message database and use a single server for all requests

C. Send media as base64 in messages and cache messages on client devices

D. Use peer-to-peer media sharing without central storage

Solution

1. Step 1: Analyze scalability needs

   Millions of users require scalable storage and fast delivery without overloading servers.

2. Step 2: Choose best architecture components

   Cloud storage handles large media files reliably; CDN speeds up delivery globally; storing URLs keeps messages lightweight.

3. Step 3: Evaluate other options

   Single server or embedding media causes bottlenecks; peer-to-peer lacks reliability and control.

4. Final Answer:

   Upload media to cloud storage, use a CDN for delivery, and store media URLs in messages -> Option A

5. Quick Check:

   Cloud storage + CDN + URLs = scalable media sharing [OK]

Hint: Combine cloud storage, CDN, and URLs for scalable media [OK]

Common Mistakes:

• Storing media in DB causing bottlenecks
• Sending base64 increases message size
• Ignoring global delivery speed