Architecture

Source layout

The src/ tree groups code by feature and by technical role. Each directory under src/feature/ holds one feature, including cpu, memory, gpu, network, disk, temperature, battery, and process. The architecture checker enforces the package placement and layer rules described below.

Package declarations are distributed with their source areas. src/package.lisp defines define-ntop-package, which adds COMMON-LISP to each package's use list. A use list makes exported symbols available without a package qualifier. The declarations live in src/shared/package.lisp, src/platform/package.lisp, src/ui/package.lisp, src/feature/<name>/package.lisp, src/app/package.lisp, and src/cli/package.lisp. ntop.asd loads the macro and these declaration files before the production source files.

Source area	Package names	Role
src/shared/	ntop.shared.domain, ntop.shared.application	Shared measurement, history, configuration, and feature collection interfaces
src/feature/<name>/	ntop.<name>.<layer>	Feature domain behavior, collection adapters, use cases, and presentation
src/platform/<os>/	ntop.platform.<os>	Operating-system APIs for Darwin and Linux
src/ui/	ntop.ui	Shared drawing, layout, formatting, theme, and input contracts
src/app/	ntop.app.domain, ntop.app.application, ntop.app.infrastructure, ntop.app.presentation	Application state, coordination, terminal lifecycle, and whole-screen presentation
src/cli/	ntop.cli	Command-line options and the process entry point

In src/shared/, src/feature/<name>/, and src/app/, the checker maps a filename stem such as domain-, application-, infrastructure-, or presentation- to the corresponding package. A descriptive suffix may follow the stem. For example, src/feature/process/domain-query-parser.lisp belongs to ntop.process.domain. Files in src/platform/<os>/ map to ntop.platform.<os>; files in src/ui/ and src/cli/ map to their area's single package.

Domain-driven design (DDD) layers and coordination

Feature packages can use four domain-driven design (DDD) layers, and each feature declares only the layers it needs. domain contains feature types and calculations. application contains use cases where a feature has them; the process feature uses it for search and termination. infrastructure collects operating-system data. presentation turns feature state into tables, graphs, and widgets. The shared packages provide domain types, history, and application configuration. The shared application package defines collection interfaces that feature infrastructure packages implement to provide samples or report unavailable data.

The ntop.app.* packages coordinate features. ntop.app.domain holds application state and actions. ntop.app.application handles input and sampling and composes state updates with rendering. ntop.app.infrastructure owns terminal and sampler lifecycle and creates platform collectors. ntop.app.presentation builds the application screen. The CLI parses options and enters through ntop.cli:main.

Allowed project dependencies

The architecture policy applies to references between ntop.* packages. It does not constrain references to external libraries.

Source package	Allowed ntop.* references
ntop.shared.domain	None
ntop.shared.application	ntop.shared.domain
ntop.<feature>.domain	ntop.shared.domain
ntop.<feature>.application	The same feature's domain, ntop.shared.domain, ntop.shared.application
ntop.<feature>.infrastructure	The same feature's domain and application, both shared packages, any ntop.platform.* package
ntop.<feature>.presentation	The same feature's domain and application, both shared packages, ntop.ui
ntop.platform.*	None
ntop.ui	ntop.shared.domain
ntop.app.*	Any ntop.* package
ntop.cli	ntop.app.*, ntop.shared.application

The checker classifies every ntop.app.* package as the composition area, where cross-feature references are allowed. This lets application code combine feature samples and presentation components without adding feature-to-feature dependencies.

Architecture checks

The ASDF ntop/test test system includes t/architecture/checker.lisp and t/architecture/checker-test.lisp. The checker derives an expected package from each production source path and filename, verifies each source file's in-package declaration, and checks package imports and package-qualified references against the dependency policy.

The tests cover representative allowed and forbidden dependencies, verify the package-definition file inventory, and scan all Lisp source files under src/ for violations. A fixture with a CPU-domain reference to the memory domain must be rejected.