Regarding Validation Rules for application composition, which of the following sentences is correct?

This statement correctly describes a fundamental principle of sound application composition in OutSystems. Isolating common business-agnostic services, core business services, or reusable UI components into separate, dedicated applications (often in the Library or Core layers) is a key best practice. This promotes reusability, loose coupling, and independent lifecycles. Other applications can then reference these shared applications, consuming their functionality without being tightly bound to their development or release cycles, which simplifies maintenance and deployment across the portfolio.

B. Mixing sponsors for an application creates conflicting priorities and release cycles, which has a direct and negative impact on its lifecycle and deployment.

C. Module-level validation is a technical check for rules like circular dependencies, but it does not guarantee a sound application composition, which also depends on business-driven application boundaries and lifecycles.

D. This statement describes an upward reference, which is a critical violation of the Architecture Canvas principles. Dependencies must always flow downwards (e.g., from End-user to Core).

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1. For Correct Answer (A) and Explanation: OutSystems Official Documentation

"Designing the architecture of your OutSystems applications

" Section: "Designing your application architecture

" Subsection: "Isolate reusable services in Core and Library applications." This section explicitly states

"Isolate reusable non-functional requirements and business-agnostic logic into modules of a Library application... Isolate reusable business logic and entities into modules of a Core application." This directly supports the practice of isolating common modules in separate applications for reuse.

2. For Incorrect Option (B): OutSystems Official Documentation

"Designing the architecture of your OutSystems applications

" Section: "Designing your application portfolio

" Subsection: "An application has a single sponsor." The documentation states

"An application has a single sponsor that defines the budget and the requirements. Having a single sponsor avoids conflicting priorities during the application lifecycle." This confirms that mixing sponsors has a direct impact.

3. For Incorrect Option (C): OutSystems Official Documentation

"Validating your architecture." This document details the specific

automatable rules for module validation (e.g.

no side references

no upward references). However

the guide "Designing the architecture of your OutSystems applications" covers the higher-level

conceptual work of defining application boundaries based on business concepts

which is essential for a sound composition and is not something module validation can check on its own.

4. For Incorrect Option (D): OutSystems Official Documentation

"Validating your architecture

" Section: "Architecture validation rules

" Rule: "No upward references between layers." This rule is explicitly listed as a critical finding. The document states

"Modules of a lower layer cannot reference modules of an upper layer

" which directly contradicts option D.