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Application Architecture by Use Case

Application Architecture by Use Case

Architecture that adapts to what you're building, not what's fashionable.

This page defines how application architecture should differ based on what you are building, not what technologies are fashionable.

Web apps, mobile platforms, SaaS products, and enterprise internal systems do not fail for the same reasons—and therefore must not be architected the same way.

Architecture must be context-aware.

Why "One Architecture Fits All" Fails

Organizations commonly standardize on:

a single architecture pattern,
a single stack,
or a single deployment model,
and then force every product into it.

This leads to:

  • over-engineered simple systems,
  • under-controlled critical systems,
  • unnecessary cost,
  • poor developer experience,
  • and fragile operations.

Clavon avoids this by anchoring architecture decisions to use case characteristics, not organizational habit.

Architecture Selection Matrix (Clavon Standard)

Before selecting an architecture, we classify the application across these axes

User Profile

External users, internal users, or both?

Interaction Style

Read-heavy, write-heavy, real-time, batch?

Data Sensitivity

Regulated, financial, personal, low-risk?

Change Frequency

Daily iteration or quarterly releases?

Scale Driver

Users, transactions, data volume, integrations?

Integration Density

Few integrations or many upstream/downstream systems?

Failure Impact

Inconvenient, costly, or catastrophic?

Architecture decisions are validated against this matrix.

1️⃣

Web Applications (Public-Facing or B2B)

Typical Characteristics

Browser-based access
Mix of read/write operations
High UX expectations
Variable traffic patterns
SEO or performance sensitivity (in some cases)

Recommended Architecture

Modular Monolith (default)

with:

  • clear domain modules
  • backend-for-frontend (BFF) where UX complexity justifies it
  • REST APIs for client communication

When to Evolve

Split services when:

  • a module has different scaling needs
  • release cadence diverges
  • ownership becomes team-specific

Common Failure Modes

Premature microservices
UI logic leaking into backend
Overuse of synchronous integrations
No performance budget or monitoring

Clavon Guidance

  • Optimize for change speed first
  • Introduce async patterns only when justified
  • Treat performance as a measurable requirement
2️⃣

Mobile Application Backends

Typical Characteristics

  • Mobile clients are unreliable (networks, latency)
  • API contracts must be stable
  • Backward compatibility is critical
  • Authentication and authorization are central

Recommended Architecture

  • API-first backend
  • Clear versioning strategy
  • Stateless services
  • Modular monolith or microservices (depending on team maturity)

Key Design Priorities

Idempotent APIs
Graceful degradation
Token-based authentication
Rate limiting and abuse protection

Common Failure Modes

Breaking API changes
Chatty APIs that drain battery
Overloaded endpoints
Poor error semantics

Clavon Guidance

Mobile clients move slower than servers. Backends must be conservative and backward-compatible.

3️⃣

SaaS Platforms (Multi-Tenant Systems)

Typical Characteristics

Multiple customers share infrastructure
Strong isolation requirements
Subscription, billing, and entitlements
Long-lived data
High expectations for availability

Recommended Architecture

Modular monolith or Carefully designed microservices

Key decisions:

  • tenant isolation model (logical vs physical)
  • data partitioning strategy
  • configuration vs customization boundaries

Tenant Isolation Models

Shared DB, tenant key

Early-stage SaaS

Separate schema

Growing SaaS

Separate DB per tenant

Regulated or high-value tenants

Common Failure Modes

Tenant data leakage
Hard-coded assumptions
Over-customization per customer
Billing logic scattered across services

Clavon Guidance

  • Treat multi-tenancy as a core domain
  • Design isolation explicitly
  • Plan migration paths between isolation levels
4️⃣

Enterprise Internal Systems

Typical Characteristics

Complex workflows
Many user roles
Heavy integration with ERP/CRM
Compliance and audit requirements
Predictable but critical usage

Recommended Architecture

  • Modular monolith with strong boundaries
  • Explicit workflow orchestration
  • Integration layer abstracting ERP/CRM dependencies

Key Design Priorities

Role-based access control
Traceability and audit trails
Stability over novelty
Integration reliability over feature velocity

Common Failure Modes

Business logic embedded in integrations
Tight coupling to ERP schemas
Poor test coverage for workflows
No ownership clarity

Clavon Guidance

Internal systems should reduce complexity, not mirror it.

5️⃣

API-First & Integration-Centric Applications

Typical Characteristics

No UI or thin UI
Heavy upstream/downstream dependencies
Contract stability is critical
Failures cascade quickly

Recommended Architecture

  • API gateway + core services
  • Strict contract governance
  • Async events for state changes
  • Synchronous APIs for commands

Common Failure Modes

No versioning strategy
Shared databases
Hidden coupling via payloads
Poor observability

Clavon Guidance

APIs are products. They require ownership, documentation, and lifecycle management.

6️⃣

Data-Intensive & Analytics-Driven Applications

Typical Characteristics

Large volumes of data
Batch and streaming workloads
Complex transformations
Downstream AI or reporting consumers

Recommended Architecture

  • Separate transactional and analytical paths
  • Event or CDC-based data ingestion
  • Clear lineage and ownership
  • Scalable storage and compute separation

Common Failure Modes

Analytics impacting transactional performance
Unclear data ownership
Manual data fixes
No monitoring of data quality

Clavon Guidance

Never mix operational workloads and analytics without strong boundaries.

Cross-Cutting Architecture Decisions

Authentication & Authorization

Centralized identity
Context-aware authorization
Token scopes and claims
Explicit service-to-service trust

Error Handling & Resilience

Timeouts and retries defined explicitly
Circuit breakers for integrations
Graceful degradation strategies
User-visible vs internal error separation

Observability

Logs, metrics, and traces per use case
Business-level events captured
SLIs aligned to user impact

Architecture Evolution Triggers (By Use Case)

Traffic growth
Scale-out specific modules
Team growth
Extract ownership-aligned services
Compliance scope increases
Strengthen controls and logging
Integration sprawl
Introduce integration layer
Performance bottlenecks
Separate hot paths

Common Anti-Patterns Across Use Cases

Reusing the same architecture blindly

Designing for hypothetical future scale

Overusing async where sync is simpler

Ignoring operational reality

Treating architecture as "done"

Deliverables Clients Receive

Use-case-specific reference architectures

Decision rationale per application type

Integration and scaling strategies

Quality and operability implications

Evolution roadmap with triggers

Cross-Service Dependencies

This page directly supports related services

Integration & API Standards

QA & Test Architecture

Cloud & Platform Engineering

AI & Data Solutions

Ready to Build Context-Aware Architecture?

Let Clavon help you design architecture that fits your use case, not fashion.