75 lines
2.5 KiB
ReStructuredText
75 lines
2.5 KiB
ReStructuredText
Architecture
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############
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This page describes the architecture of PostgREST.
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Bird's Eye View
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===============
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.. image:: ../_static/arch.png
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Code Map
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========
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This section talks briefly about various important modules.
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The starting points of the program are:
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- `Main.hs <https://github.com/PostgREST/postgrest/blob/main/main/Main.hs>`_
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- `CLI.hs <https://github.com/PostgREST/postgrest/blob/main/src/PostgREST/CLI.hs>`_
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- `App.hs <https://github.com/PostgREST/postgrest/blob/main/src/PostgREST/App.hs>`_
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``App.hs`` is then in charge of composing the different modules.
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Auth
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----
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`Auth.hs <https://github.com/PostgREST/postgrest/blob/main/src/PostgREST/Auth.hs>`_ is in charge of :ref:`authn`.
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Api Request
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-----------
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`ApiRequest.hs <https://github.com/PostgREST/postgrest/blob/main/src/PostgREST/ApiRequest.hs>`_ is in charge of parsing the URL query string (following PostgREST syntax), the request headers, and the request body.
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A request might be rejected at this level if it's invalid. For example when providing an unknown media type to PostgREST or using an unknown HTTP method.
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Plan
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----
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Using the Schema Cache, `Plan.hs <https://github.com/PostgREST/postgrest/blob/main/src/PostgREST/Plan.hs>`_ fills in out-of-band SQL details (like an ``ON CONFLICT (pk)`` clause) required to complete the user request.
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A request might be rejected at this level if it's invalid. For example when doing resource embedding on a nonexistent resource.
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Query
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-----
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`Query.hs <https://github.com/PostgREST/postgrest/blob/main/src/PostgREST/Query.hs>`_ generates the SQL queries (parametrized and prepared) required to satisfy the user request.
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Only at this stage a connection from the pool might be used.
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Schema Cache
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------------
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`SchemaCache.hs <https://github.com/PostgREST/postgrest/blob/main/src/PostgREST/SchemaCache.hs>`_ is in charge of :ref:`schema_cache`.
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Config
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------
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`Config.hs <https://github.com/PostgREST/postgrest/blob/main/src/PostgREST/Config.hs>`_ is in charge of :ref:`configuration`.
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Admin
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-----
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`Admin.hs <https://github.com/PostgREST/postgrest/blob/main/src/PostgREST/Admin.hs>`_ is in charge of the :ref:`admin_server`.
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HTTP
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----
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The HTTP server is provided by `Warp <https://aosabook.org/en/posa/warp.html>`_.
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Listener
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--------
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`Listener.hs <https://github.com/PostgREST/postgrest/blob/main/src/PostgREST/Listener.hs>`_ is in charge of maintaining a `LISTEN session <https://www.postgresql.org/docs/current/sql-listen.html>`_
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that keeps the :ref:`schema_cache` and the :ref:`in_db_config` up to date.
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