.. _developer_architecture: Architecture and internals ========================== HTTomo separates orchestration from scientific processing. Backend libraries implement algorithms, ``httomo-backends`` describes how those functions behave inside a pipeline, and HTTomo validates, schedules and executes them. Execution path -------------- #. The CLI loads and validates the pipeline configuration. #. The UI and transform layers construct method wrappers and insert framework operations such as intermediate saving. #. The pipeline is divided into sections with compatible processing patterns. #. The loader supplies data to the runner, which distributes each section into per-rank chunks and memory-sized blocks. #. Wrappers invoke backend methods and pass the resulting block onwards. #. Dataset stores handle in-memory or disk-backed transitions between sections. Read :ref:`execution model ` and :ref:`Core concepts ` first. The implementation-oriented concepts are: .. toctree:: :maxdepth: 1 ../introduction/concepts/wrappers ../introduction/concepts/memory_estimators Repository responsibilities --------------------------- ``httomo`` Pipeline validation, loading, orchestration, MPI distribution, data stores, wrappers, monitoring and command-line behaviour. Backend library The scientific implementation and its numerical tests. ``httomo-backends`` Execution metadata, generated method templates, memory estimation, padding and output-shape information. See :ref:`developers_httomo_backends`. Most new scientific methods require changes to the backend library and ``httomo-backends`` only. Change HTTomo when orchestration or wrapper behaviour must also change. Public entry points ------------------- The :ref:`api` is exhaustive and includes implementation modules. New code should depend on the narrowest stable interface available, particularly the pipeline, method-wrapper, loader, method-repository and monitoring interfaces. Avoid importing from generated documentation paths or relying on private names.