Architecture Domains (Business, Data, Application, Technology)

can often feel overwhelming: frameworks, diagrams, acronyms abound. But strip it down, and it's about breaking down complexity into manageable, interlinked parts.

Imagine your enterprise as a house: the living room (Business Architecture), where purpose, culture, and direction are defined; the pantry (Data Architecture), storing resources (data) that power every action; the appliances (Application Architecture), the tools and applications that perform work; and the plumbing and wiring behind the walls (Technology Architecture), ensuring everything is powered, connected, secure.

On their own, these parts are just disconnected spaces. Together, they make a home. These four domains are the backbone of EA: Business, Data, Application, Technology. This article dives into what each is, how they interrelate, examines modern evolutions, defines relevant roles, shows how to govern, and explains how modern tools make this practicable.

Why enterprises need Domains: from chaos to coherence

Generalising and partitioning architecture into clear domains is not just a matter of structure, it is a way to turn complexity into clarity. By defining domains, enterprises gain specialisation (each area has dedicated expertise and ownership), accountability (responsibilities are clearly distributed), and traceability (a business goal can be followed down to the data, applications, and technology that support it).

Domains also enable adaptability: with well-defined boundaries, one part of the landscape can evolve (whether migrating applications, modernising infrastructure, or revising data policies) without destabilising the rest. Above all, they provide a shared language between business and IT, helping decision-makers see the whole enterprise as a coherent system rather than a collection of silos.

The Four rooms of Enterprise Architecture

Here are the four domains in detail, their responsibilities, dependencies, and what excellence looks like.

The four domains of EA

Business Architecture: defining purpose and capabilities

Business Architecture is where strategy meets structure.

• What it includes: Value streams / business capabilities; business goals, strategy; organisational structure; business process design; stakeholder roles.
• What you achieve: Clear priorities; understanding of what matters most; alignment between what the business wants and what IT should deliver.
• Interactions: Sets the benchmark for what data is needed; informs what applications are required; constrains technology regarding performance, scale, compliance, regulatory needs.
• Key actors: Business Architects, C-level executives (CEO, COO, CIO), business unit leaders, project owners.

Data Architecture: from raw information to strategic asset

Data Architecture transforms raw data into strategic leverage.

• What it includes: Data models; master data, metadata; data pipelines; governance policies; data quality, privacy & security; data integration across systems.
• What you achieve: Trust in data; regulatory compliance; ability to derive insights; ability to support analytics, AI projects.
• Interactions: Applications depend on data structures and quality; technology must support data storage, processing, governance; business decisions depend on data correctness.
• Key actors: Data Architects, Data Engineers, Data Stewards, Data Analysts, Data Scientists, Chief Data Officer (CDO).

Application Architecture: the tools that get work done

Applications are where business processes are digitized and executed.

• What it includes: Application inventory; integration architecture; API strategy; custom vs COTS vs SaaS decisions; modularity, domain-driven design.
• What you achieve: Reduced duplication; more agility; better maintainability; clearer ownership.
• Interactions: Needs data feeds; supports business capabilities; constrained by technology (platforms, network, deployment, scaling).
• Key actors: Application Architects, Solution Architects, Product Managers, Application Owners, Business Analysts, Delivery Managers.

Technology Architecture: infrastructure as enabler

The unseen but essential domain: Infrastructure, platforms, non-functional qualities.

• What it includes: Hosting, networks, cloud/on-premises, security, platform services, operational practices; performance, resilience, scalability.
• What you achieve: Stable foundation; ability to scale; prevention of technical debt; optimized costs.
• Dependencies: Applications impose requirements; data volume and characteristics affect storage and processing technologies; business needs define service levels and availability.
• Key actors: Technology Architects, Infrastructure Managers, Security Architects, Cloud Engineers, DevOps teams, IT Operations.

Modern Perspectives on Domain Architecture

In large or geographically distributed organisations, federated or multi-domain enterprise architecture has become a necessity. Rather than centralising every decision, responsibilities are distributed: domain architects or business units own parts of the landscape, while a central governance framework maintains coherence. This balance helps avoid fragmentation without stifling agility, ensuring that local contexts are respected while the enterprise still speaks a common architectural language.

Alongside this shift, the rise of automation, discovery, and analytics is transforming how architecture is practiced. Modern platforms can automatically:

• catalogue applications, data, and infrastructure;
• monitor real usage;
• detect redundant or obsolete assets;
• visualise dependencies across domains.

With dashboards and scenario modelling, architects are moving away from static documentation and towards living, data-driven maps that support real-time decision-making.

Roles, governance, tools: making domains real

No domain stays useful without people, governance, and tools to operationalize it.

Roles & responsibilities within EA

• Enterprise Architect: Strategic oversight, alignment of all domains; ownership of architectural roadmap; dealing with legacy vs future technology; guiding transformation; influencing senior leadership.
• Domain Architect(s): Each domain has a domain architect (e.g. Data Architect, Application Architect, Technology Architect). They focus on domain-specific modeling, technical decisions, ensuring compliance with overarching EA.
• Business Architect: Often works directly with business stakeholders to map business capabilities, value streams, strategic goals. Ensures business requirements are well-reflected in all domains.
• Solution / Technical Architect: Bridge the gap between domain/enterprise architecture and the implementers/developers. Technical Architects specialize in particular technologies; Solution Architects design end-to-end solutions. Ensuring that the design adheres to principles, meets non-functional requirements, and integrates domain artefacts properly.

Governance & best practices

Making domains effective requires more than definitions; it requires governance. An EA governance framework typically defines roles and responsibilities, decision rights, processes, and metrics. But governance is not just about bureaucracy. It is about rhythm and accountability: regular portfolio reviews to assess applications, audits to ensure data governance, or infrastructure lifecycle management to anticipate obsolescence.

Equally important is communication. Architects must engage with stakeholders across business, operations, data, and security, ensuring alignment and buy-in. In large or distributed organisations, federated decision-making is often necessary: some choices are made centrally to preserve coherence, while others are delegated locally to domain architects or line-of-business teams to preserve agility. This balance between central oversight and local autonomy is what keeps enterprise architecture both consistent and adaptable.

Conclusion

The four domains (Business, Data, Application, Technology) are not just academic: they are essential to create coherence, alignment, agility, and governance in any enterprise. But defining domains is only the beginning. For EA to deliver lasting value, you need:

• Clear roles and accountabilities
• Governance that maintains consistency, control, and adaptability
• Tools that make architecture visible, actionable, and maintainable

Modern enterprises, however, need more than theory. They need visual, accessible, and collaborative tools to bring domain architectures to life. That is where Boldo positions itself: making enterprise architecture both strategic and simple.

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