Software Architecture: Basic Principles & System Integration

This article is a definition of terms covering architecture fundamentals and system integration – including exam questions and tags.

In a Nutshell

In practice, greenfield projects are rare: architecture must account for extension, integration, and environment migration (cloud/OS/DB) – so systems remain maintainable and extensible.

Compact Technical Description

Software architecture describes structure, components, relationships, and technologies. In integration projects, typical challenges are:

• Legacy systems (poorly documented, monolithic)
• Interfaces/data formats/protocols
• Decision: refactoring vs. reimplementation
• Environment migration (on-prem → cloud, Windows → Linux, database migration)

Technical debt, modular decomposition, layered models, and clear interfaces are key levers.

Exam-Relevant Key Points

• Architecture = structure/communication/dependencies
• Consider legacy systems (IHK-relevant)
• Interface capability as design requirement
• Refactoring instead of rebuild when core logic is stable
• Integration via REST/middleware/adapter
• Security: API security, legacy database access
• Cost-effectiveness: reuse vs. new development
• Documentation: diagrams, interface specifications, migration strategy

Core Components

1. Current state analysis
2. Technical debt
3. Requirements reconciliation
4. Interface concept
5. Integration strategy (wrapper/proxy/adapter)
6. Target environment
7. Migration (big bang vs. incremental)
8. Refactoring
9. Compatibility testing
10. Documentation/architectural decisions

Practical Example

Inventory management system (monolith) gets modern web UI:
- REST API as middleware
- Adapter legacy data structure → JSON
- OpenAPI/Swagger documentation
- reuse existing logic

Advantages and Disadvantages

Advantages

• Using existing systems saves time/costs
• Integration extends system lifespan

Disadvantages

• Legacy systems often poorly documented
• Interfaces difficult to add retroactively
• Environment migration poses risks

Typical Exam Questions (with Short Answer)

1. What is a legacy system? An old system that continues to operate.
2. How do you connect legacy systems? Interfaces, adapters/wrappers, middleware.
3. When to refactor instead of rebuild? When core logic is stable.

Further Information

1. https://arc42.org/
2. https://c4model.com/