In a highly concurrent, distributed system designed with a stateless architecture, what is the primary challenge in maintaining a consistent view of a user's authenticated session across multiple requests without relying on sticky sessions?

Implementing a globally accessible, shared state store that can be queried by any service instance per request.

Ensuring every request carries the full user profile data in its header.

Synchronizing local caches on each server instance for session tokens.

Minimizing network latency introduced by re-authenticating the user with every single interaction.

A microservice responsible for processing real-time video streams needs to maintain buffering information, frame synchronization, and retransmission requests for each active stream. Which architectural style is inherently more suitable for this specific microservice, and why?

Stateful, because stream-specific context must be continuously available for efficient processing.

Stateless, because it simplifies horizontal scaling of processing nodes.

Stateless, as it reduces memory footprint per server instance.

Stateful, as it eliminates the need for persistent storage.

Consider a web application where users frequently switch between different server instances due to load balancing. If the application relies on server-side session objects (e.g., HTTP session in Java EE) for storing user preferences and cart items, what is the *most likely* immediate consequence for the user experience when switching instances?

Loss of session data, leading to a degraded or reset user experience.

Improved performance due to distributed processing.

Automatic replication of session data to the new server.

Increased security as session data is not tied to a single server.

Which of the following describes the most significant challenge when implementing fault tolerance in a highly stateful distributed system compared to a stateless one?

Recovering lost state upon node failure in a stateful system is significantly more complex and resource-intensive.

Stateless systems require more complex load balancing algorithms.

Stateful systems inherently have higher network latency due to increased data transfer.

Stateless systems are more vulnerable to security breaches in session management.

A system uses a message queue to decouple microservices. If a 'payment processing' microservice is designed to be purely stateless, what *critical dependency* must be ensured for it to successfully process a payment request that arrives via the queue?

All necessary payment details (customer ID, amount, transaction ID) must be fully contained within the message itself.

The message queue must maintain the payment processing state across retries.

The microservice must have exclusive access to a dedicated database for payment records.

A sticky session must be maintained between the message queue and the microservice.

Which architectural decision *best promotes* the horizontal scalability and resilience of a web application's frontend API layer, even if its backend data store is inherently stateful?

Designing the API endpoints to be purely RESTful and stateless.

Implementing an in-memory session store on each API server.

Utilizing a highly synchronized, distributed transaction manager across all API servers.

Maintaining long-lived TCP connections between clients and specific API servers.

In the context of a highly available distributed database, why is the concept of 'eventual consistency' often embraced for stateless application layers accessing it, rather than requiring strong consistency for every read operation?

Requiring strong consistency for every read would drastically increase latency and reduce availability, counteracting stateless benefits.

Strong consistency is easier to implement in a stateless environment.

Eventual consistency provides stronger transactional guarantees for write operations.

Stateless applications cannot interact with strongly consistent data stores.

A financial trading system requires extremely low-latency processing of market data, where each incoming tick needs to be evaluated against a user's complex, real-time trading strategy. Which architectural choice for the strategy execution engine would provide the *most optimal balance* of performance and determinism, despite the scaling challenges?

A stateful service instance that loads and maintains a user's strategy in memory for continuous evaluation.

A purely stateless microservice that fetches the strategy from a database for every single tick.

A distributed queue system that buffers all market ticks and dispatches them to any available stateless processor.

A serverless function that executes the strategy for each tick, caching the strategy locally for brief periods.

When migrating a monolithic, stateful application to a microservices architecture, what is the *most critical step* to enable the microservices to operate effectively as stateless components?

Externalizing all session state and application-specific context into a distributed, shared data store.

Implementing a new user interface for each microservice.

Ensuring all persistent data is moved to a centralized relational database.

Rewriting all business logic in a functional programming language.

Which of the following common HTTP features directly contributes to the stateless nature of web applications by providing a mechanism for clients to send server-side context with each request, effectively mimicking state without the server retaining it?

HTTP Cookies and Authorization Headers (e.g., JWTs).

A serverless function is designed to resize images uploaded to a cloud storage bucket. Why is this a natural fit for a stateless architecture?

Each image resizing operation is an independent task that does not depend on prior requests or server-side memory.

Serverless functions are inherently more secure than stateful applications.

Stateless architectures are always cheaper to operate than stateful ones.

Serverless platforms provide built-in mechanisms for state management.

In a distributed microservice environment, when a service needs to maintain a complex 'conversation' or workflow state across multiple asynchronous interactions (e.g., an order fulfillment process), what is the most appropriate pattern if the individual services are designed to be stateless?

Using a state machine pattern, where the state is externalized and managed by a dedicated workflow engine or database.

Implementing sticky sessions across all microservices.

Passing the entire conversation state as a payload in every message between services.

Relying on each service to temporarily store its part of the conversation state in its local memory.

A company is building a real-time multiplayer online game. While the game client itself manages much of the visual state, which component of the server-side architecture *most likely requires* a stateful design to ensure fair gameplay and synchronized actions among players?

The game session server, responsible for tracking player positions, scores, and game world state.

The login authentication service.

The player profile management service.

What is the primary architectural benefit of designing an API Gateway to be largely stateless, even when interacting with stateful backend services?

It allows the API Gateway to scale independently and easily, without concern for losing client-specific context.

It forces backend services to become stateless.

It simplifies the overall system design by eliminating the need for authentication.

It enables the API Gateway to cache all backend responses indefinitely.

Which of the following scenarios presents the *most compelling reason* to favor a stateful architectural component over a stateless one, despite the associated complexities?

Implementing a long-running computation that requires continuous access to intermediate results and checkpointing.

Processing individual, self-contained HTTP requests for static content.

Serving product catalog data from a cached database.

Performing user authentication and authorization based on a JWT.

Stateful vs Stateless Architecture

Stateful vs Stateless Architecture - Test Paper