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58 lines
3.3 KiB
ReStructuredText
58 lines
3.3 KiB
ReStructuredText
Checking API stability
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======================
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We have committed not to alter Corda's API so that developers will not have to keep rewriting their CorDapps with each
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new Corda release. The stable Corda modules are listed :ref:`here <internal-apis-and-stability-guarantees>`. Our CI process runs an "API Stability"
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check for each GitHub pull request in order to check that we don't accidentally introduce an API-breaking change.
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Build Process
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-------------
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As part of the build process the following commands are run for each PR:
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.. code-block:: shell
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$ gradlew generateApi
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$ .ci/check-api-changes.sh
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This ``bash`` script has been tested on both MacOS and various Linux distributions, it can also be run on Windows with the
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use of a suitable bash emulator such as git bash. The script's return value is the number of API-breaking changes that it
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has detected, and this should be zero for the check to pass. The maximum return value is 255, although the script will still
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correctly report higher numbers of breaking changes.
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There are three kinds of breaking change:
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* Removal or modification of existing API, i.e. an existing class, method or field has been either deleted or renamed, or
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its signature somehow altered.
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* Addition of a new method to an interface or abstract class. Types that have been annotated as ``@DoNotImplement`` are
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excluded from this check. (This annotation is also inherited across subclasses and sub-interfaces.)
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* Exposure of an internal type via a public API. Internal types are considered to be anything in a ``*.internal.`` package
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or anything in a module that isn't in the stable modules list :ref:`here <internal-apis-and-stability-guarantees>`.
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Developers can execute these commands themselves before submitting their PR, to ensure that they haven't inadvertently
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broken Corda's API.
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How it works
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------------
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The ``generateApi`` Gradle task writes a summary of Corda's public API into the file ``build/api/api-corda-<version>.txt``.
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The ``.ci/check-api-changes.sh`` script then compares this file with the contents of ``.ci/api-current.txt``, which is a
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managed file within the Corda repository.
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The Gradle task itself is implemented by the API Scanner plugin. More information on the API Scanner plugin is available `here <https://github.com/corda/corda-gradle-plugins/tree/master/api-scanner>`_.
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Updating the API
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----------------
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As a rule, ``api-current.txt`` should only be updated by the release manager for each Corda release.
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We do not expect modifications to ``api-current.txt`` as part of normal development. However, we may sometimes need to adjust
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the public API in ways that would not break developers' CorDapps but which would be blocked by the API Stability check.
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For example, migrating a method from an interface into a superinterface. Any changes to the API summary file should be
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included in the PR, which would then need explicit approval from either `Mike Hearn <https://github.com/mikehearn>`_, `Rick Parker <https://github.com/rick-r3>`_ or `Matthew Nesbit <https://github.com/mnesbit>`_.
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.. note:: If you need to modify ``api-current.txt``, do not re-generate the file on the master branch. This will include new API that
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hasn't been released or committed to, and may be subject to change. Manually change the specific line or lines of the
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existing committed API that has changed. |