62 lines
1.5 KiB
ReStructuredText
62 lines
1.5 KiB
ReStructuredText
Request Life Cycle
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==================
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This section describes the sequence of events happening for each request
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answered by the :ref:`http-user-interface`.
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.. image:: ../_static/request_life_cycle.png
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1. request
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----------
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The user makes a request to the :ref:`http-user-interface`.
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- The request is matched against the route table.
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- :program:`kapow` provides a `HANDLER_ID` to identify this request and don't
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mix it with other requests that could be running concurrently.
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2. spawn
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--------
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:program:`kapow` spawns the executable specified as entrypoint in the matching
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route.
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The default entrypoint is :command:`/bin/sh`; let's focus on this workflow.
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The spawned entrypoint is run with the following variables added to its
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environment:
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- :envvar:`KAPOW_HANDLER_ID`: Containing the `HANDLER_ID`
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- :envvar:`KAPOW_DATAAPI_URL`: With the URL of the :ref:`http-data-interface`
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- :envvar:`KAPOW_CONTROLAPI_URL`: With the URL of the :ref:`http-control-interface`
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3. ``kapow set /response/body banana``
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--------------------------------------
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During the lifetime of the shell, the :ref:`request and response resources
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<resource-tree>` are available via these commands:
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- ``kapow get /request/...``
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- ``kapow set /response/...``
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These commands use the aforementioned environment variables to read data
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from the user request and to write the response. They accept data either as
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arguments or from `stdin`.
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4. exit
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-------
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The shell dies. Long live the shell!
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5. response
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-----------
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:program:`kapow` finalizes the original request. Enjoy your banana now.
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