59 lines
1.4 KiB
ReStructuredText
59 lines
1.4 KiB
ReStructuredText
Request Life Cycle
|
|
==================
|
|
|
|
This section describes the sequence of events happening for each request
|
|
answered by the `User HTTP Interface`.
|
|
|
|
.. image:: ../_static/request_life_cycle.png
|
|
|
|
|
|
1. request
|
|
|
|
The user makes a request to the `User HTTP Interface`.
|
|
|
|
- The request is matched against the route table
|
|
|
|
- ``kapow`` provides a `HANDLER_ID` to identify this request and don't mix it
|
|
with other requests that could be running concurrently.
|
|
|
|
2. spawn
|
|
|
|
``kapow`` spawns the executable specified as entrypoint in the matching
|
|
route.
|
|
|
|
The default entrypoint is ``/bin/sh``; we'll explain this workflow for now.
|
|
|
|
The spawned entrypoint is run with the following variables added to its
|
|
environment:
|
|
|
|
- ``KAPOW_HANDLER_ID``: Containing the `HANDLER_ID`
|
|
- ``KAPOW_DATAAPI_URL``: With the URL of the `Data HTTP Interface`
|
|
- ``KAPOW_CONTROLAPI_URL``: With the URL of the `Control HTTP Interface`
|
|
|
|
3. ``kapow set /response/body banana``
|
|
|
|
During the lifetime of the shell, the request and response resources are
|
|
available via these commands:
|
|
|
|
- ``kapow get /request/...``
|
|
|
|
- ``kapow set /response/...``
|
|
|
|
- These commands use the aforementioned environment variables to read data from
|
|
the user request and to write the response.
|
|
|
|
- They accept data either as arguments or from stdin.
|
|
|
|
4. exit
|
|
|
|
The shell dies.
|
|
|
|
5. response
|
|
|
|
``kapow`` finalizes the original request.
|
|
|
|
|
|
.. todo::
|
|
|
|
link to resource tree
|