Service-Oriented Architecture (SOA) Quiz

Q1. An e-commerce company changed the internal database structure of its product-catalog service for optimization, but the service’s interface (contract) to consumers remained unchanged and no clients were affected. Which SOA design principle is demonstrated by this scenario? Service autonomy
Loose coupling
Service discoverability
Service statelessness

Q2. A widely used Order service needs to offer new features without disrupting existing consumers. What is the best approach to modify the service in line with SOA best practices? Modify the existing service contract and require all clients to update their integrations immediately
Version the service by introducing a new interface (e.g., Order Service v2) while continuing to support the original contract
Freeze the service at its current version to avoid any changes
Implement the new features internally but keep the contract unchanged, assuming clients will not notice

Q3. Instead of hard-coding service endpoints, a company uses a central directory where services register themselves and clients look up services by name at runtime. What SOA component or concept does this describe? A service registry enabling runtime discovery
Point-to-point service integration
Hard-coded endpoint references
A load balancer with sticky routing

Q4. In an enterprise SOA, a central ESB handles all message routing and transformations but becomes a performance bottleneck. Which alternative integration approach can alleviate this “God ESB” problem? Use decentralized, lightweight API gateways or direct service-to-service communication
Upgrade the ESB hardware and continue routing all interactions through it
Enforce a single, enterprise-wide data model so the ESB has less varied work
Merge multiple services into one larger service to reduce ESB traffic

Q5. Service A places a request for Service B on a message queue because the operation is long-running and Service B may be offline. Which advantage of asynchronous messaging does this illustrate? Improved fault tolerance and decoupling through reliable queuing
Immediate user response because results return faster than synchronous calls
Simpler client logic with no error handling required
Faster overall business-transaction completion

Q6. A financial service requires each SOAP message to be encrypted and signed end-to-end, even through intermediaries. Which security standard best meets this requirement? Transport Layer Security (TLS)
WS-Security (message-level XML encryption and signatures)
API keys over HTTP
A network firewall

Q7. An organization uses SAML tokens in WS-Security for internal SOAP services but is building public REST APIs for partners. Which authentication approach is more appropriate for these new REST services? Continue using WS-Security with SAML tokens in HTTP headers
Use OAuth 2.0 to issue JSON Web Tokens (JWT)
Allow anonymous access since partners are trusted
Use HTTP Basic Authentication over SSL

Q8. A booking service’s payment succeeds, but the subsequent hotel-reservation call fails. Without distributed XA transactions, which pattern maintains consistency? Use a compensating transaction (e.g., refund the payment)
Wrap both calls in a two-phase commit
Always perform the hotel reservation before payment
Lock both databases until all steps complete

Q9. Operations struggles to identify slow services and ensure SLA compliance in a complex SOA. What should be implemented to address this? Comprehensive monitoring, distributed tracing, and dashboards for each service
Weekly manual testing of all services
Deploy all services on the same server
Rely solely on database query logs

Q10. SOA governance enforces a single canonical model and routes every call through a central ESB, causing long design cycles and bottlenecks. Which governance pitfall is exemplified? Over-specification with an overly centralized “God ESB”
Lack of any service-contract standards
Building services that are too coarse-grained
Not having a dedicated governance team

Q11. A user-profile service maintains no session state; every request contains all needed data and is processed independently. Which SOA principle does this illustrate? Service statelessness
Service discoverability
Service autonomy
Service composability

Q12. Three teams independently built customer-profile services, duplicating functionality. Which SOA principle was neglected? Service reusability
Loose coupling
Service autonomy
Service statelessness

Q13. A team created hundreds of ultra-fine-grained services, leading to chatty, high-latency communication. Which design guideline could have prevented this? Design coarse-grained services aligned with business capabilities
Use as many small services as possible
Always prefer remote calls over local calls
Rely on network speed and add hardware

Q14. A business process involving Services X, Y, Z can use a central orchestrator or event-driven choreography. To minimize tight coupling and a single point of failure, which approach is more suitable? Event-driven choreography
Central orchestration because it simplifies communication
Central orchestration because it means fewer points of failure
Both approaches are identical

Q15. A company moving from traditional SOA to microservices keeps a centralized ESB for all communication. Why is this problematic? A central ESB reintroduces a bottleneck and undermines independent deployability
Microservices require REST, so an ESB cannot be used
Each microservice must use a different programming language, which an ESB prevents
There is no difference; ESB usage poses no issues

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