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Application Developer Practice Exam
Question 1. Which component in TARS is primarily responsible for service registration and discovery? A) TarsAdmin B) TarsRegistry C) TarsNode D) TarsConfig Answer: B Explanation: TarsRegistry maintains a list of all active services and their locations, enabling other components to discover them. Question 2. In the TARS architecture, the Admin Console is used for which of the following actions? A) Serializing data for RPC calls B) Managing service deployment and patches C) Handling low‑level network sockets D) Storing persistent cache data Answer: B Explanation: TarsAdmin (the Admin Console) provides a web UI to upload patches, start/stop services, and monitor health. Question 3. Which of the following best describes the role of TarsNode? A) Generates client stubs from .tars files B) Executes service instances and processes RPC requests C) Stores configuration templates for all services D) Acts as a reverse proxy for HTTP traffic Answer: B
Application Developer Practice Exam
Explanation: TarsNode runs the actual service code, handling incoming RPC calls and returning responses. Question 4. The TARS binary protocol is more efficient than JSON/HTTP mainly because it: A) Uses compression algorithms like gzip by default B) Sends data in a compact binary format without field names C) Requires fewer network hops due to UDP usage D) Implements built‑in caching of responses Answer: B Explanation: Binary encoding eliminates verbose field names, reducing payload size and parsing overhead. Question 5. Which file extension is used for defining TARS interfaces and data structures? A) .proto B) .idl C) .tars D) .svc Answer: C Explanation: TARS uses .tars files to declare services, methods, and structs in its own IDL. Question 6. When a TARS client invokes a method synchronously, the call blocks until: A) The request reaches the registry B) The server sends a response or a timeout occurs C) The client receives a heartbeat from the node D) The service instance is redeployed
Application Developer Practice Exam
D) Store all data in a single MySQL schema Answer: B Explanation: Microservices are isolated to enable independent scaling, deployment, and fault isolation. Question 10. Which of the following is NOT a typical advantage of using TARS over a monolithic architecture? A) Independent scaling of services B) Simplified debugging due to shared memory space C) Fault isolation between services D) Ability to deploy services in different programming languages Answer: B Explanation: Monoliths share memory, which can simplify debugging, but microservices (including TARS) isolate processes, making debugging more complex. Question 11. The TARS protocol uses which transport layer by default? A) HTTP/ B) TCP C) UDP D) SCTP Answer: B Explanation: TARS is built on top of TCP to guarantee ordered and reliable delivery of binary messages. Question 12. Which of the following best describes the purpose of TarsConfig? A) Provides runtime configuration values to services
Application Developer Practice Exam
B) Manages the lifecycle of Docker containers C) Executes health‑check scripts on nodes D) Generates documentation from .tars files Answer: A Explanation: TarsConfig stores key‑value pairs that services can read at startup or dynamically. Question 13. When a new service version is uploaded via the TarsWeb console, the typical sequence is: A) Registry updates, then node restarts automatically B) Patch is stored, then administrators manually trigger deployment on nodes C) Service is compiled on the node, then registry is notified D) Configuration hierarchy is rewritten, then the service restarts itself Answer: B Explanation: The patch is uploaded to the management server; admins then choose which nodes to deploy the new version. Question 14. In Dockerized TARS deployments, which component is usually responsible for persisting logs outside the container? A) TarsLog B) TarsNode C) TarsRegistry D) TarsAdmin Answer: A Explanation: TarsLog aggregates logs from containers and can forward them to external systems (e.g., ELK).
Application Developer Practice Exam
Explanation: Hash routing uses a deterministic hash (e.g., user ID) so related requests are routed to the same instance, aiding caching. Question 18. The "IDC" concept in TARS stands for: A) Inter‑Data Center routing for cross‑region traffic B) Internet Data Center grouping for localized service discovery C) Internal Diagnostic Component for health checks D) Incremental Data Cache for fast reads Answer: B Explanation: IDC groups nodes by their physical data center, allowing the registry to prefer nearby instances. Question 19. When implementing a "Set" deployment in TARS, the main goal is to: A) Provide versioned rollbacks for each service B) Isolate services per business unit or region C) Enable automatic scaling based on load D) Share a common database across all services Answer: B Explanation: A "Set" groups services so that only nodes belonging to that set receive the deployment, providing logical isolation. Question 20. Circuit breaking in TARS helps to: A) Automatically restart failed nodes B) Prevent cascading failures by short‑circuiting calls to unhealthy services C) Increase the size of the thread pool during spikes D) Encrypt RPC payloads for security
Application Developer Practice Exam
Answer: B Explanation: A circuit breaker monitors failure rates and, when thresholds are exceeded, stops forwarding requests to the problematic service. Question 21. Log dyeing in TARS is useful for: A) Coloring console output for readability B) Tagging a specific request ID so its path can be traced across services C) Encrypting log files at rest D) Automatically deleting logs after a retention period Answer: B Explanation: Dyeing assigns a unique marker to a request, allowing developers to follow its journey through multiple microservices. Question 22. Which component aggregates remote logs from all TARS nodes? A) TarsStat B) TarsProperty C) TarsLog D) TarsRegistry Answer: C Explanation: TarsLog collects logs emitted by services and can forward them to centralized storage or monitoring systems. Question 23. Custom service metrics in TARS are reported via: A) TarsStat and TarsProperty APIs B) Direct writes to MySQL tables C) Standard output streams only
Application Developer Practice Exam
A) PostgreSQL B) SQLite C) MySQL D) MongoDB Answer: C Explanation: The official TARS management platform uses MySQL as its backend store. Question 27. DCache in TARS is primarily designed for: A) Persistent relational storage B) Distributed in‑memory caching and key‑value storage C) Logging aggregation across nodes D) Service discovery across data centers Answer: B Explanation: DCache provides a high‑performance, distributed cache layer for fast data retrieval. Question 28. When mounting a shared volume for TARS services in Docker, which technology is often used to provide NFS functionality? A) GlusterFS B) CephFS C) Host‑based NFS server with -v /nfs:/data flag D) OverlayFS Answer: C Explanation: A typical Docker run command mounts an NFS export from the host into the container using the -v option.
Application Developer Practice Exam
Question 29. The built‑in Interface Debugger in TarsWeb allows developers to: A) Edit .tars files directly in the browser B) Invoke service methods with custom parameters and view raw responses C) Generate performance reports automatically D) Deploy new Docker images without CI/CD pipelines Answer: B Explanation: The debugger sends RPC calls to a selected service and displays the serialized response for testing. Question 30. TarsBenchmark is used to: A) Verify correctness of serialization logic B) Measure latency and throughput of RPC calls under load C) Generate code stubs for new languages D) Perform static analysis of .tars files Answer: B Explanation: TarsBenchmark runs repeated RPC invocations to assess performance characteristics. Question 31. Which error code indicates that a TARS service could not be found in the registry? A) 5001 B) 4040 C) 1002 D) 2003 Answer: B Explanation: TARS uses 4040 to signal “service not found” similar to HTTP 404 semantics.
Application Developer Practice Exam
Explanation: Patches are versioned service binaries uploaded through the admin console. Question 35. Which of the following is the correct order of steps to add a new service to a TARS cluster? A) Write .tars → Generate stubs → Build binary → Upload patch → Deploy to nodes B) Deploy nodes → Write .tars → Upload patch → Build binary → Register service C) Register service → Write .tars → Build binary → Deploy → Upload patch D) Build binary → Write .tars → Upload patch → Register service → Deploy Answer: A Explanation: The typical workflow is to define the interface, generate code, compile, upload the artifact, and then deploy. Question 36. Which of the following is NOT a supported language for TARS code generation? A) C++ B) Java C) Go D) Ruby Answer: D Explanation: Official TARS tools generate code for C++, Java, Go, and PHP, but not Ruby. Question 37. When configuring a TARS service to use asynchronous callbacks, the client must provide: A) A REST endpoint URL B) A callback function identifier that the server can invoke later C) An XML schema for the response
Application Developer Practice Exam
D) A shared memory segment handle Answer: B Explanation: Asynchronous calls include a callback ID or object so the server can send the result back when ready. Question 38. The purpose of the “heartbeat” mechanism in TARS nodes is to: A) Synchronize system clocks across nodes B) Notify the registry that the node is alive and healthy C) Flush cached data to persistent storage D) Rotate log files automatically Answer: B Explanation: Periodic heartbeats allow the registry to maintain an up‑to‑date view of node availability. Question 39. Which of the following statements about TARS service versioning is true? A) Only one version can exist in the registry at a time B) Versions are distinguished by a numeric “patch” identifier and can coexist C) Version numbers are ignored during service discovery D) The registry automatically merges two versions into a single instance Answer: B Explanation: TARS supports multiple versions (patches) simultaneously; clients can specify which version to call. Question 40. In a Kubernetes‑based TARS deployment, which object is best suited for storing configuration templates that should be shared across many pods? A) ConfigMap
Application Developer Practice Exam
A) tarscli B) tarsreg C) tarsadmin D) tarsprobe Answer: A Explanation: tarscli includes subcommands to list services, their versions, and endpoints. Question 44. A “service instance” in TARS is uniquely identified by which combination? A) Service name + node IP + port B) Registry URL + client ID C) Patch version + database schema D) Configuration template name + log level Answer: A Explanation: Each running instance is distinguished by its service name, IP address, and listening port. Question 45. The “set” deployment mechanism ensures that a patch is only applied to nodes that: A) Belong to the same IDC group B) Have the same operating system version C) Are members of a predefined logical group (Set) D) Share identical hardware specifications Answer: C Explanation: Sets are logical groupings (e.g., by business line) used to limit deployment scope.
Application Developer Practice Exam
Question 46. Which of the following is a recommended practice for handling large payloads in TARS RPC calls? A) Increase the TCP window size manually B) Switch to JSON over HTTP for better streaming C) Use streaming or chunked transfer support provided by TARS D) Encode data as base64 strings within the binary protocol Answer: C Explanation: TARS supports streaming large objects, allowing them to be sent in chunks rather than a single massive packet. Question 47. In TARS, the term “dyeing” refers specifically to: A) Changing log file permissions at runtime B) Tagging a request with a unique identifier for tracing C) Encrypting payloads using a per‑request key D) Compressing logs before transmission Answer: B Explanation: Dyeing is the act of marking a request so its path can be followed across services. Question 48. Which of the following best explains why TARS uses a binary protocol rather than text‑based protocols? A) Binary protocols are easier for humans to read B) Binary data can be directly mapped to native structures, reducing serialization overhead C) Text protocols cannot be encrypted D) Binary protocols guarantee zero latency Answer: B
Application Developer Practice Exam
D) requires Answer: A Explanation: depends_on defines start‑up order among services in Docker‑compose. Question 52. What is the primary benefit of using “hash‑based routing” for a user‑session service in TARS? A) Guarantees equal load distribution regardless of session count B) Ensures that all requests for the same user hit the same node, preserving session state in memory C) Reduces network latency by selecting the nearest geographic node D) Allows automatic failover to any node without session loss Answer: B Explanation: Hash routing maps a key (e.g., user ID) to a specific node, keeping session data local. Question 53. Which of the following statements about TARS’ “property” system is FALSE? A) Properties can be updated at runtime and are visible to monitoring tools B) Properties are stored in the same table as service metadata in MySQL C) Properties support numeric, string, and boolean types D) Properties are sent to TarsStat for aggregation Answer: B Explanation: Properties are not persisted in the management MySQL; they are kept in memory and reported via TarsStat. Question 54. When configuring a TARS service to run in multiple IDC groups, the registry will:
Application Developer Practice Exam
A) Duplicate the service definition for each IDC automatically B) Route client requests to the nearest IDC based on client IP C) Require manual configuration of separate service names per IDC D) Ignore IDC tags and treat all nodes as a single pool Answer: B Explanation: The registry can prioritize nodes belonging to the same IDC as the client, reducing cross‑IDC latency. Question 55. Which of the following is a correct way to enable dynamic configuration reload for a running TARS service? A) Restart the service with the new config file B) Send a SIGHUP signal to the process after updating TarsConfig C) Modify the .tars IDL and recompile the service D) Change the Docker image version and redeploy Answer: B Explanation: TARS processes listen for SIGHUP (or a specific internal command) to reload configuration without a full restart. Question 56. In TARS, the “patch” version number is typically incremented when: A) A new MySQL schema is added B) Only the logging level changes C) Binary code or interface definitions are updated D) The service is moved to a different IDC Answer: C Explanation: Patches represent compiled binaries and possibly updated interfaces; changing only config does not require a new patch.
