API gateway concept in HLD - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define the main role of an API gateway.

HLD

An API gateway acts as a [1] between clients and backend services.

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

Aproxy

Bdatabase

Cfrontend

Dcache

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing API gateway with a database or cache.

Thinking API gateway is a frontend component.

An API gateway acts as a proxy that routes client requests to the appropriate backend services.

2fill in blank

medium

Complete the code to describe a key feature of API gateways.

HLD

API gateways often provide [1] to control access and protect backend services.

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

Aauthentication

Bload balancing

Cdata storage

Dlogging

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing authentication with load balancing or logging.

Thinking API gateway stores data.

API gateways commonly provide authentication to verify client identity before forwarding requests.

3fill in blank

hard

Fix the error in the description of API gateway functionality.

HLD

API gateway [1] requests directly to databases without any processing.

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

Aignores

Bsends

Croutes

Dblocks

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing options that imply no processing or blocking requests.

Misunderstanding the routing role of API gateway.

The API gateway routes requests to backend services, not directly to databases without processing.

4fill in blank

hard

Fill both blanks to complete the API gateway request flow.

HLD

Client sends a request to the API gateway, which [1] the request and then [2] it to the correct backend service.

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

Avalidates

Bignores

Cforwards

Dblocks

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing options that imply ignoring or blocking requests.

Confusing validation with ignoring.

The API gateway first validates the request to ensure it is correct and authorized, then forwards it to the appropriate backend service.

5fill in blank

hard

Fill all three blanks to describe API gateway features in request handling.

HLD

The API gateway [1] incoming requests, [2] them for security, and [3] responses back to clients.

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

Areceives

Bvalidates

Csends

Dignores

Attempts:

3 left

💡 Hint

Common Mistakes

Selecting 'ignores' for any blank.

Mixing up the order of receiving, validating, and sending.

The API gateway receives requests, validates them to ensure security, and sends responses back to clients.

Practice

1. What is the primary role of an API gateway in a system architecture?

easy

A. It replaces the need for backend services.

B. It stores all the data for the application.

C. It directly manages the database connections.

D. It acts as a single entry point for client requests to backend services.

Solution

1. Step 1: Understand the role of API gateway

   An API gateway serves as the main entry point for clients to access multiple backend services, simplifying communication.

2. Step 2: Eliminate incorrect roles

   Storing data, managing database connections, or replacing backend services are not responsibilities of an API gateway.

3. Final Answer:

   It acts as a single entry point for client requests to backend services. -> Option D

4. Quick Check:

   API gateway = single entry point [OK]

Hint: API gateway = one door for all client requests [OK]

Common Mistakes:

• Confusing API gateway with database or storage
• Thinking API gateway replaces backend services
• Assuming API gateway manages data directly

2. Which of the following is the correct function of an API gateway in handling client requests?

easy

A. Directly querying the database for each request.

B. Serving static files like images and videos.

C. Routing requests to appropriate backend services.

D. Replacing the client application.

Solution

1. Step 1: Identify API gateway functions

   An API gateway routes incoming client requests to the correct backend services based on the request type or URL.

2. Step 2: Remove unrelated functions

   Serving static files, querying databases directly, or replacing clients are not typical API gateway roles.

3. Final Answer:

   Routing requests to appropriate backend services. -> Option C

4. Quick Check:

   API gateway routes requests = C [OK]

Hint: API gateway directs traffic to backend services [OK]

Common Mistakes:

• Thinking API gateway queries databases directly
• Confusing API gateway with CDN or static server
• Assuming API gateway replaces client apps

3. Consider this simplified API gateway flow:

Client -> API Gateway -> Service A (auth) -> Service B (data)

If the API gateway receives a request and Service A rejects it due to failed authentication, what will the client receive?

medium

A. Authentication error response

B. Data from Service B

C. No response (timeout)

D. Success response with empty data

Solution

1. Step 1: Trace request through services

   The request first goes to Service A for authentication. If Service A rejects it, the request does not proceed further.

2. Step 2: Determine client response

   Since authentication failed, the API gateway returns an authentication error to the client instead of data or success.

3. Final Answer:

   Authentication error response -> Option A

4. Quick Check:

   Failed auth = error response [OK]

Hint: Failed auth stops flow, returns error [OK]

Common Mistakes:

• Assuming data is returned despite failed auth
• Thinking client gets no response (timeout)
• Believing success with empty data is sent

4. An API gateway is configured to route requests to multiple services. However, clients report 404 errors for valid endpoints. What is the most likely cause?

medium

A. Backend services are down.

B. API gateway routing rules are misconfigured.

C. Client requests are malformed.

D. API gateway is overloaded.

Solution

1. Step 1: Analyze 404 error meaning

   A 404 error means the requested resource was not found, often due to incorrect routing or URL mapping.

2. Step 2: Identify likely cause in API gateway

   If backend services are up and clients send correct requests, misconfigured routing rules in the API gateway cause 404 errors.

3. Final Answer:

   API gateway routing rules are misconfigured. -> Option B

4. Quick Check:

   404 = routing misconfiguration [OK]

Hint: 404 usually means wrong routing path [OK]

Common Mistakes:

• Assuming backend services are down without checking
• Blaming client requests without validation
• Thinking overload causes 404 errors

5. You want to design an API gateway that aggregates data from three backend services before responding to the client. Which approach best fits this requirement?

hard

A. API gateway calls all three services, combines their responses, then sends one response to client.

B. API gateway caches data and never calls backend services.

C. API gateway sends separate responses from each service to the client.

D. API gateway forwards client requests directly to one backend service only.

Solution

1. Step 1: Understand aggregation requirement

   The API gateway must collect data from multiple services and combine it into a single response for the client.

2. Step 2: Evaluate options for aggregation

   Forwarding to one service or sending separate responses does not aggregate data. Caching alone does not fulfill aggregation if fresh data is needed.

3. Final Answer:

   API gateway calls all three services, combines their responses, then sends one response to client. -> Option A

4. Quick Check:

   Aggregation = combine multiple service responses [OK]

Hint: Aggregate by combining multiple service responses [OK]

Common Mistakes:

• Thinking forwarding to one service aggregates data
• Sending multiple responses instead of one combined
• Assuming caching replaces aggregation