S90.02 Sample Questions & Answers

The One-Way MEP is ideal for this 'fire-and-forget' scenario. The service consumer sends a message to the service provider and does not expect a response. The interaction is complete once the message is sent. This decouples the client from the processing workflow, allowing for asynchronous communication. Request-Response would imply the client waits for a reply.

Rapid elasticity is the ability to provision and release computing resources elastically, in some cases automatically, to scale rapidly outward and inward commensurate with demand. This directly addresses the need to handle traffic spikes during sales and scale down during quiet periods, thereby optimizing performance and cost. Measured Service is related, as it enables the pay-per-use model that makes elasticity financially viable, but elasticity is the core capability for adjusting capacity.

Service agents are classified as passive or active. A passive agent, such as a monitoring or logging agent, observes and processes message content without modifying it. An active agent, such as a data transformation or validation agent, actively modifies the message content. Since this service only logs the message and does not alter it, it is a passive service agent.

The abstract definition in WSDL consists of , , and . These define the data types, the messages exchanged, and the operations, respectively, without specifying any protocol. The concrete definition consists of the (which specifies the protocol, like SOAP over HTTP) and (which specifies the endpoint address). Therefore, the and elements provide the concrete implementation details.

The enum keyword in JSON Schema is used to restrict a value to a fixed set of values. It must be an array with at least one element, where each element is unique. To meet the requirement, the schema would include "enum": ["DEBUG", "INFO", "WARN", "ERROR"]. The pattern keyword uses regular expressions, and const restricts the value to a single specific value, not a set.

The 201 Created status code is the most appropriate response for a successful POST request that results in the creation of a new resource. The server should also include a Location header in the response, containing the URI of the newly created resource (e.g., /orders/123). While 200 OK indicates success, 201 Created is more specific and idiomatic for resource creation.

The stateless constraint means that each request from a client to the server must contain all the information needed to understand and process the request. The server should not store any client context between requests.

The uniform interface constraint simplifies and decouples the architecture. It consists of four sub-constraints: resource identification (URIs), resource manipulation through representations (e.g., JSON), self-descriptive messages, and hypermedia as the engine of application state (HATEOAS).

Horizontal scaling (scaling out) involves adding more instances of a service, typically behind a load balancer. For a stateless application with massive, unpredictable traffic spikes, this is the superior approach. It provides high availability (if one instance fails, others can handle the load) and superior elasticity. Vertical scaling (scaling up) has physical limits, often requires downtime, and creates a single point of failure.

The SOAP Header is an optional element within the SOAP Envelope designed specifically for extensibility. It allows for the addition of features and processing instructions that are not part of the core message payload. This is precisely how the entire suite of WS-* specifications (like WS-Security, WS-Addressing, WS-ReliableMessaging) adds functionality to SOAP messages, by defining specific header blocks.

The UDDI registry is conceptually divided into sections. The White Pages contain business information such as name, address, and contact details, allowing users to discover services based on a known business identity. The Yellow Pages categorize businesses by industry or location (like a phone book's yellow pages). The Green Pages provide the technical details about the services themselves, including pointers to their WSDL contracts.