An administrator wants to describe the internal architecture and request flow for a Query service of an executed DQM report. How is this done?

The request flow for a Dynamic Query Mode (DQM) report begins when a user request is processed and communicated between services via the BI Bus (BIBus). The request is routed to the Query Service, which is the core engine for DQM. A defining architectural feature of DQM is its sophisticated query planner. It parses the report specification to generate a logical query plan (representing the business request) and then transforms it into an optimized physical query plan (representing how to retrieve the data). This process is often described as creating "two trees." The physical plan is then executed against the database via an RDBMS adapter, with results being retrieved and cached to optimize performance before the final report is generated.

A. This is incorrect because the BI Bus is the communication infrastructure, not the query execution engine. The Query Service performs the execution, and this option omits the critical query parsing step.

B. This is incorrect as it oversimplifies the process by omitting the fundamental DQM step of parsing the request into logical and physical query plans ("two trees"), which is a key differentiator.

C. This is incorrect because the request does not originate at the Query Service. It is routed to the Query Service from other services (like the Report Service) via the BI Bus infrastructure.

1. IBM Redbooks, "IBM Cognos Dynamic Query" (SG24-8121-00)

Page 8, Section 1.2.2, "Query execution": "The query service receives an abstract representation of a query from a client such as the report service. The query service plans the query by creating a logical plan... The query service then transforms the logical plan to a physical plan that is specific to the data sources that are being queried." This text directly supports the concept of parsing the request into two plans or "trees".

Page 7, Figure 1-3, "Dynamic query mode architecture": This diagram illustrates the interaction where the Report Service sends a request to the Query Service, which then interacts with data sources. The BI Bus facilitates this inter-service communication.

2. IBM Knowledge Center, Cognos Analytics 11.1.x, "Dynamic query mode"

Section: "Query execution": The documentation states, "The query service plans and executes queries in a series of steps... The query service validates the query and analyzes it to produce a logical query plan... The query service converts the logical plan into a physical query plan." This confirms the multi-stage planning process central to DQM and represented by the "two trees" concept in the correct answer.