architecture-overview

Development

Use when exploring the aiida-core codebase structure, looking for key files, or understanding how packages relate to each other.

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AiiDA Core Architecture

Source layout

The source code lives under src/aiida/ with these main packages:

Package	Purpose
`brokers/`	Message broker interface (RabbitMQ via `kiwipy`)
`calculations/`	Built-in calculations
`cmdline/`	CLI (`verdi` command) built with `click`
`common/`	Shared utilities, exceptions, warnings, constants
`engine/`	Workflow engine: process runner, daemon, persistence, transport tasks (with `plumpy` dependency)
`manage/`	Configuration management, manager singleton
`orm/`	Object-relational mapping: nodes, groups, users, computers, querybuilder
`parsers/`	Built-in parser plugins
`plugins/`	Plugin entry point system and factories
`repository/`	File repository abstraction layer
`restapi/`	Flask-based REST API (soon to be replaced by `aiida-restapi`)
`schedulers/`	Built-in HPC scheduler plugins (SLURM, PBS, SGE, LSF, etc.)
`storage/`	Storage backends (primarily `psql_dos` (`sqlite_dos`) for PostgreSQL (SQLite) + disk-objectstore)
`tools/`	Utility tools (graph visualization, archive operations, data dumping, etc.)
`transports/`	Built-in Transport plugins (SSH, local)
`workflows/`	Built-in workflows

Key entry points

Area	Key file(s)	Purpose
Engine core	`src/aiida/engine/processes/process.py`	Base `Process` class
CalcJob	`src/aiida/engine/processes/calcjobs/calcjob.py`	`CalcJob` implementation
CalcJob file ops	`src/aiida/engine/daemon/execmanager.py`	File copying, job submission, retrieval
WorkChain	`src/aiida/engine/processes/workchains/workchain.py`	`WorkChain` implementation
ORM node	`src/aiida/orm/nodes/node.py`	Base `Node` class
QueryBuilder	`src/aiida/orm/querybuilder.py`	Query interface for the provenance graph
Process runner	`src/aiida/engine/runners.py`	`Runner` executes and submits processes
Plugin factories	`src/aiida/plugins/factories.py`	`DataFactory`, `CalculationFactory`, etc.
Storage ABC	`src/aiida/orm/implementation/storage_backend.py`	`StorageBackend` abstract base class
Transport ABC	`src/aiida/transports/transport.py`	`Transport`, `BlockingTransport`, `AsyncTransport`
Scheduler ABC	`src/aiida/schedulers/scheduler.py`	`Scheduler` base class

Other notable files: ProcessBuilder (engine/processes/builder.py), Computer (orm/computers.py), Config (manage/configuration/config.py), Manager (manage/manager.py), DaemonClient (engine/daemon/client.py), Profile (manage/configuration/profile.py), psql_dos backend (storage/psql_dos/backend.py), RabbitmqBroker (brokers/rabbitmq/broker.py), Repository (repository/repository.py).

Database and file storage

ORM: SQLAlchemy. File storage: disk-objectstore. Migrations: Alembic (under src/aiida/storage/psql_dos/migrations/).
Main backend: psql_dos (PostgreSQL + disk-objectstore). Lightweight: sqlite_dos (SQLite + disk-objectstore).

Abstract base classes (ABCs)

AiiDA defines ABCs for extensible components. To create a plugin, implement the corresponding ABC and register it as an entry point.

ABC	Location	Purpose	Entry point
`Transport`	`aiida.transports.transport`	File transfer and remote command execution	`aiida.transports`
`Scheduler`	`aiida.schedulers.scheduler`	HPC job scheduler interface	`aiida.schedulers`
`Parser`	`aiida.parsers.parser`	Parse calculation outputs	`aiida.parsers`
`StorageBackend`	`aiida.orm.implementation.storage_backend`	Database and file storage	`aiida.storage`
`AbstractCode`	`aiida.orm.nodes.data.code.abstract`	Code/executable representation	`aiida.data`
`CalcJobImporter`	`aiida.engine.processes.calcjobs.importer`	Import existing calculation results	`aiida.calculations.importers`

Quick API overview via stubs

To get a compact view of a module's public API without reading the full source (which can pollute context), generate type stubs:

uv run stubgen -p aiida.orm -o /tmp/stubs             # public API only
uv run stubgen -p aiida.orm -o /tmp/stubs --include-private  # include _private members

The generated .pyi files show only signatures, classes, and type annotations, useful for understanding an API surface quickly. stubgen ships with mypy, which is part of the pre-commit optional dependencies (uv sync --extra pre-commit or just uv sync if already installed).

Project configuration

pyproject.toml (dependencies, entry points, ruff/mypy config), uv.lock, .pre-commit-config.yaml, .readthedocs.yml, .github/workflows/, .docker/.