Message Queue for Apache RocketMQ is a distributed message queue service designed for reliable asynchronous communication, decoupling, and peak shaving. It ensures messages are delivered even if the consumer is temporarily unavailable, which perfectly fits the scenario of decoupling the order and inventory services and handling service outages.

Log Service is a fully managed service for real-time log collection, consumption, query, and analysis. Using its agent is the standard, serverless method to centralize logs from ECS instances. It provides long-term retention policies, powerful query capabilities, and integrates with other Alibaba Cloud services, meeting the audit requirement without infrastructure management.

Both ACK and SAE are excellent solutions for this scenario. ACK with autoscalers offers fine-grained, policy-driven scaling for Kubernetes-native applications. SAE is a fully managed serverless container platform that automatically scales based on metrics like CPU and memory, abstracting away cluster management. The choice often depends on the team’s preference for control (ACK) versus simplicity (SAE). The exam expects knowledge that multiple Alibaba Cloud services can solve dynamic scaling effectively.

OSS event notification integrated with Function Compute is the ideal serverless, event-driven pattern for this. When a user uploads an image (object) to OSS, it automatically triggers a Function Compute function. This function can process the image (resize it) and save the thumbnails back to OSS, all without managing servers and without blocking the user’s upload request.

Transparent Data Encryption (TDE) is a feature of ApsaraDB RDS that performs real-time I/O encryption and decryption of the data and log files at the storage layer. This meets the requirement for ‘encryption at rest.’ SSL/TLS encrypts data in transit, not at rest. Application-level encryption adds complexity and doesn’t encrypt underlying database files. OSS is for object storage, not RDS block storage.

The combination of SLB and an auto-scaling group is the standard, managed solution for providing high availability and handling traffic surges on Alibaba Cloud. It allows multiple ECS instances to share the load, and the auto-scaling group can automatically add instances based on metrics like memory utilization, providing a resilient and scalable architecture without a full platform migration.

Resource Orchestration Service (ROS) is an Infrastructure as Code (IaC) service that allows you to model and provision Alibaba Cloud resources using JSON or YAML templates. You define the resources and their dependencies in a template, and ROS handles the creation, update, and deletion in the correct order. This ensures consistency, repeatability, and version control for your infrastructure.

The cache-aside (lazy-loading) pattern is standard, but the key mitigation is ‘pre-warming.’ For predictable hot items (like a breaking news article), the system can proactively load the article into the cache before the traffic surge hits, or immediately after publishing with a very short TTL for the first fetch. This prevents a thundering herd of database requests from millions of users requesting the same uncached key simultaneously.

Function Compute’s /tmp directory provides ephemeral disk space that persists across invocations of the same function instance (warm start). By caching the file here and adding logic to refresh it based on a timestamp or version check (e.g., using an OSS object header), you can avoid redundant downloads for most invocations, significantly reducing latency and cost.

Message Queue for Apache RocketMQ is a distributed message queue service designed for reliable asynchronous communication, decoupling, and peak shaving. It ensures messages are delivered even if the consumer is temporarily unavailable, which perfectly fits the scenario of decoupling the order and inventory services and handling service outages.0