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GENERAL DEVELOPMENT NOTES

Project's sources are accessible from a Mercurial version control repository hosted at BitBucket.

Project development should be tracked in the TODO.txt file.

  • Exact formatting is not important as long as its content is kept formatted consistently.
  • Done tasks should be marked as such and not deleted.

Separate sections below:

For additional design, research & development project notes see the project's notes/ folder.

TOP-LEVEL PROJECT FILES & FOLDERS

.hg/
.hgignore
.hgtags
  • Mercurial version control related data.
build/
dist/
suds_jurko.egg-info/
  • Folders created during project setup procedure (build/install).
notes/
  • Internal project design, research & development notes.
suds/
  • Basic project source code.
tests/
  • Project test code.
tools/
  • Project development & setup utility scripts. Related internal Python modules are located under its suds_devel/ package folder.
MANIFEST.in
  • Build system configuration file listing the files to be included in the project's source distribution packages in addition to those automatically added to those packages by the used package preparation system.
HACKING.rst
LICENSE.txt
README.txt
TODO.txt
  • Internal project documentation.
setup.cfg
  • Basic project Python configuration.
setup.py

  • Standard Python project setup script.

  • Usage examples:

    setup.py --help

    show detailed usage information

    setup.py --help-commands

    show detailed setup.py command list

    setup.py build

    build the project

    setup.py install

    build & install the project

    setup.py register

    register a project release at PyPI

    setup.py sdist

    prepare a source distribution

    setup.py upload

    upload prepared packages to PyPI

  • Usage examples requiring setuptools:

    setup.py develop

    prepare the development environment (add the project folder to the Python module search path) the same as if installed using easy_install -e or pip install -e

    setup.py test

    run the project test suite (requires pytest)

PYTHON COMPATIBILITY

Base sources should remain Python 2.x compatible. Since the original project states aiming for Python 2.4 compatibility we do so as well.

The Python 3.0 minor release is not supported. See Python 3.0 support subsection below for more detailed information.

Test & setup code needs to be implemented using Python 2 & 3 compatible source code. Setup & setup related scripts need to be implemented so they do not rely on other pre-installed libraries.

These backward compatibility requirements do not affect internal development operations such as setup.py support for uploading a new project distribution package to PyPI. Such operations need to be supported on the latest Python 2 & 3 releases only and no additional backward compatibility is either tested or guaranteed for them.

The following is a list of backward incompatible Python features not used in this project to maintain backward compatibility:

Features missing prior to Python 2.5

  • any & all functions.

  • with statement.

  • BaseException class introduced and KeyboardInterrupt & SystemExit exception classes stopped being Exception subclasses.

    • This means that code wanting to support Python versions prior to this release needs to re-raise KeyboardInterrupt & SystemExit exceptions before handling the generic 'Exception' case, unless it really wants to gobble up those special infrastructural exceptions as well.

  • try/except/finally blocks.

    • Prior to this Python release, code like the following:

      try:
    A
except XXX:
    B
finally:
    C

      was considered illegal and needed to be written using nested try blocks as in:

      try:
    try:
        A
    except XXX:
        B
finally:
    C

  • yield expression inside a try block with a finally clause.

    • Prior to this Python release, code like the following:

      try:
    yield x
finally:
    do_something()

      is considered illegal, but can be replaced with legal code similar to the following:

      try:
    yield x
except:
    do_something()
    raise
do_something()

Features missing prior to Python 2.6

  • bytes type.
  • Byte literals, e.g. b"quack".
  • Class decorators.
  • fractions module.
  • numbers module.
  • String format() method.
  • Using the with statement from Python 2.5.x requires the from __future__ import with_statement.

Features missing prior to Python 2.7

  • Dictionary & set comprehensions.
  • Set literals.

Features missing in Python 3.0 & 3.1

  • py2to3 conversion for source files with an explicitly specified UTF-8 BOM.

Python 3.0 support

Python 3.0 release has been marked as deprecated almost immediately after the release 3.1. It is not expected that this Python release is actively used anywhere in the wild. That said, if anyone really wants this version supported - patches are welcome.

At least the following problems have been found with Python 3.0:

  • None of the tools required to properly test our project (setuptools, pip, virtualenv, tox, etc.) will work on it.
  • When you attempt to setuptools project with Python 3.0, it attempts to use the sys.stdout.detach() method introduced only in Python 3.1. This specific issue could be worked around by using sys.stdout.buffer directly but the actual fix has not been attempted. If anyone wants to take this route though and work on supporting setuptools on Python 3.0 - be warned that it will most likely have other issues after this one as well.
  • When applying py2to3 to the project sources, Python will use the current user's locale encoding instead of the one specified in the project sources, thus causing the operation to fail on some source files containing different unicode characters unless the user's environement uses some sort of unicode encoding by default, e.g. will fail on some test scripts when run on Windows with eastern European regional settings (uses the CP1250 encoding).

RELEASE PROCEDURE

  1. Document the release correctly in README.rst.
  2. Test the project build with the latest available setuptools project and update the ez_setup.py setuptools installation script as needed.
  • Use the latest available & tested setuptools release.
  • If a new setuptools release drops support for an older Python release, update our setup.py script to use an older setuptools installation script when run using the no longer supported Python release.
    • For example, setuptools version 2.0 dropped support for Python 2.4 & 2.5 and so setup.py uses a separate ez_setup_1_4_2.py setuptools installation script with Python versions older than 2.6.
  1. Version identification.

  • Official releases marked with no extra suffix after the basic version number.

  • Alfa releases marked with the suffix .a#.

  • Beta releases marked with the suffix .b#.

  • Release candidate releases marked with the suffix .rc#.

  • Development releases marked with the suffix .dev#.

  • Version ordering (as recognized by pip & setuptools):

    0.5.dev0 < 0.5.dev1 < 0.5.dev5
  < 0.5.a0.dev0 < 0.5.a0.dev5 < 0.5.a0
  < 0.5.a3.dev0 < 0.5.a3.dev5 < 0.5.a3
  < 0.5.b0.dev0 < 0.5.b0.dev5 < 0.5.b0
  < 0.5.b3.dev0 < 0.5.b3.dev5 < 0.5.b3
  < 0.5.rc0.dev0 < 0.5.rc0.dev5 < 0.5.rc0
  < 0.5.rc3.dev0 < 0.5.rc3.dev5 < 0.5.rc3
  < 0.5
< 0.5.1.dev0 < ...
  ...
  < 0.5.1
< 0.6.dev0 < ...
  ...
  < 0.6
< 1.0.dev0 < ...
  ...
  < 1.0
  1. Tag in Hg.
  • Name the tag like release-<version-info>, e.g. release-0.5.
  1. Prepare official releases based only on tagged commits.
  • Official releases should always be prepared based on tagged revisions with no local changes in the used sandbox.
  • Prepare source distribution packages (both .zip & .tar.bz2 formats) and upload the prepared source packages to PyPI.
    • Run setup.py sdist upload.
  • Prepare wheel packages for Python 2 & 3 using the latest Python 2 & 3 environments with the wheel package installed and upload them to PyPI.
    • Run setup.py bdist_wheel upload using both Python 2 & 3.
  • Upload the prepared source & wheel packages to the project site.
    • Use the BitBucket project web interface.
  1. Next development version identification.
  • If this was a development release.
    • Bump up the existing .dev# suffix, e.g. change 0.8.dev2 to 0.8.dev3.
  • If this was a non-development release.
    • Bump up the forked project version counter (may add/remove/bump alfa/beta/release-candidate mark suffixes as needed).
    • Add the .dev0 suffix, e.g. as in 0.8.dev0.
  1. Notify whomever the new release might concern.

DEVELOPMENT & TESTING ENVIRONMENT

In all command-line examples below pyX, pyXY & pyXYZ represent a Python interpreter executable for a specific Python version X, X.Y & X.Y.Z respectively.

Setting up the development & testing environment

tools/setup_base_environments.py script should be used for setting up the basic Python environments so they support testing our project. The script can be configured from the main project Python configuration file setup.cfg. It implements all the backward compatibility tweaks and performs additional required package installation that would otherwise need to be done manually in order to be able to test our project in those environments.

These exact requirements and their related version specific tweaks are not documented elsewhere so anyone interested in the details should consult the script's sources.

The testing environment is generally set up as follows:

  1. Install clean target Python environments.
  2. Update the project's setup.py configuration with information on your installed Python environments.
  3. Run the tools/setup_base_environments.py script.

Some older Python environments may have slight issues caused by varying support levels in different used Python packages, but the basic testing functionality has been tested to make sure it works on as wide array of supported platforms as possible.

Examples of such issues:

  • Colors not getting displayed on a Windows console terminal, with possibly ANSI color code escape sequences getting displayed instead.
  • pip utility can not be run from the command-line using the py -m pip syntax for some older versions. In such cases use the more portable py -c "import pip;pip.main()" syntax instead.
  • Some specific older Python versions (e.g. 2.4.3) have no SSL support and so have to reuse installations downloaded by other Python versions.

Running the project tests - tools/run_all_tests.py script

tools/run_all_tests.py script is a basic poor man's tox development script that can be used for running the full project test suite using multiple Python interpreter versions on a development machine.

Intended to be replaced by a more portable tox based or similar automated testing solution some time in the future.

Can be configured by tweaking the main project Python configuration file setup.cfg:

  • List of target Python environments.
  • Each target Python environment's invocation command.

Requires the target Python environment already be set up, and all the packages required for running the project test suite installed. See the Setting up the development & testing environment section for more detailed information.

Automatically installs the project in editable mode in all tested Python environments.

Caveats:

  • This method does not allow you to provide any extra pytest options when running the project test suite.

Running the project tests - setup.py test command

Project tests can also be run for a specific Python environment by running the project's setup.py script in that environment and invoking its test command. E.g. run a command like one of the following ones from the top level project folder:

py243 setup.py test
py27 setup.py test
py3 setup.py test

Note that the setup.py script always needs to be called from the top level project folder.

For most Python versions, the target Python environment needs not be set up prior to running this command. Where possible (e.g. not for Python 2.4.x or 3.1.x versions), any missing testing requirements will be installed automatically, but not directly into the target environment but in the current folder instead. This functionality should be considered a band-aid though, and setting up the target environment can be better done as described in the Setting up the development & testing environment section.

The setup.py test command will build the project if needed and run its test suite in the target Python environment. The project does not need to be preinstalled into the target Python environment for this operation to work, and neither will the operation leave it installed.

Unless a more restricted test set is selected using pytest specific command-line options, setup.py test command runs the complete project test suite.

Specific pytest command-line options may be provided by passing them all as a single whitespace separated string tunnelled via the setup.py test command's --pytest-args/-a command-line option.

For example, the following command will run only tests containing binding in their name, will stop on first failure and will automatically drop into Python's post-mortem debugger on failure:

setup.py test -a "-k binding -x --pdb"

Caveats:

  • This method does not currently allow passing pytest specific command-line options containing embedded whitespace.
  • When running the setup.py test command in a Windows Python 2.5 environment without an included ctypes module (e.g. 64-bit CPython 2.5 distribution does not include ctypes) and having it automatically install the colorama package version older than 0.1.11, you will get benign error messages reporting colorama's atexit handlers failing. Running the same command again avoids the issue since the colorama package will then already be installed. Suggested workaround is to use a colorama package version 0.3.2 or newer.

Running the project tests - using pytest directly

To have greater control over the test suite and be able to specify additional pytest options on the command-line, or be able to run the tests on a different project installation (e.g. official release installed directly from PyPI), do the following:

  1. Install the project into the target Python environment.

  • Installing the project can be done by either installing it directly into the target Python environment using one of the following commands (paths used assume the commands are being run from the top level project folder):

    setup.py install
easy_install .
pip install .

    Or the project can be installed in editable mode using one of the following commands (so it does not need to be reinstalled after every source code change):

    setup.py develop
easy_install -e .
pip install -e .

  • The installation step can be skipped if running Python 2 based project tests, and doing so from the top level project folder.

  1. Run tests using pytest.

  • If using Python 2.x:

    • Run pytest from the project's top level or tests folder:

      py2 -m pytest

  • If using Python 3.x:

    • Since the project uses py2to3 source conversion, you need to build the project in order to generate the project's Python 3 sources before they can be tested. If the project has been installed in editable mode, then simply run the following from the top level project folder:

      setup.py build

      and if it has not then rebuild and reinstall it using one of the following commands:

      setup.py develop
setup.py install

      Note that you might need to manually remove the build folder in order to have its contents regenerated when wanting to run the test suite using a different Python 3.x interpreter version, as those sources are regenerated based solely on the original & processed source file timestamp information and not the Python version used to process them.

    • Run pytest from the the project's tests folder:

      py3 -m pytest

Each specific test module can also be run directly as a script.

Notes on the folder from which to run the tests:

  • When running tests from a folder other than the top level project folder, the tested project version needs to first be installed in the used Python environment.
  • Python 2 tests can be run from the top level project folder, in which case they will work even if the project has not been explicitly installed in the used Python environment. And even if another project version has been installed into the used Python environment, that one will be ignored and the one in the current folder used instead.
  • Python 3 tests can not be run from the top level project folder or they would attempt and fail to use Python 2 based project sources found in the current folder.

See the pytest documentation for a detailed list of available command-line options. Some interesting ones:

-l show local variable state in tracebacks
--tb=short shorter traceback information for each failure
-x stop on first failure
--pdb enter Python debugger on failure

Setting up multiple parallel Python interpreter versions on Windows

On Windows you might have a problem setting up multiple parallel Python interpreter versions in case their major and minor version numbers match, e.g. Python 2.4.3 & 2.4.4. In those cases, standard Windows installer will automatically remove the previous installation instead of simply adding a new one. In order to achieve such parallel setup we suggest the following steps:

  1. Install the first version in a dummy folder, and do so for the current user only.
  2. Copy the dummy target folder to the desired folder for the first installation, e.g. Python243.
  3. Uninstall the original version.
  4. Set up a shortcut or a batch script (e.g. py243.cmd) for running this interpreter without having to have it added to the system path.
  5. Repeat the steps for the second installation.

Installing Python for the current user only is necessary in order to make Python install all of its files into the target folder and not move some of them into shared system folders.

Note that this will leave you without start menu or registry entries for these Python installations. Registry entries should be needed only if you want to run some external Python package installation tool requiring those entries in order to determine where to install its package data. In that case you can set those entries manually, e.g. by using a script similar to the one found at http://nedbatchelder.com/blog/201007/installing_python_packages_from_windows_installers_into.html.

PYTHON 2/3 SOURCE CODE COMPATIBILITY

These are notes related to maintaining Python 2/3 source code compatibility in parts of this project that require it.

Use the six <http://pythonhosted.org/six> Python 2/3 compatibility support package to make the compatibility patches simpler. Where a solution provided by six can not be used, explicitly explain the reason why in a related code comment.

Do not use u"..." Python unicode literals since we wish to support Python 3.1 & 3.2 versions which do not support them. Useful site for easily converting unicode strings to their unicode-escape encoded representation which can then be used with the six.u() helper function:

http://www.rapidmonkey.com/unicodeconverter

EXTERNAL DOCUMENTATION

STANDARDS CONFORMANCE

There seems to be no complete standards conformance overview for the suds project. This section contains just some related notes, taken down while hacking on this project. As more related information is uncovered, it should be added here as well, and eventually this whole section should be moved to the project's user documentation.

Interpreting message parts defined by a WSDL schema

  • Each message part is interpreted as a single parameter.
    • What we refer to here as a 'parameter' may not necessarily correspond 1-1 to a Python function argument passed when using the suds library's Python function interface for invoking web service operations. In some cases suds may attempt to make the Python function interfaces more intuitive to the user by automatically unwrapping a parameter as defined inside a WSDL schema into multiple Python function arguments.
  • In order to achieve interoperability with existing software 'in the wild', suds does not fully conform to the WSDL 1.1 specification with regard as to how message parts are mapped to input data contained in SOAP XML web service operation invocation request documents.
    • WSDL 1.1 standard states:
      • 2.3.1 Message Parts.
        • A message may have message parts referencing either an element or a type defined in the WSDL's XSD schema.
        • If a message has a message part referencing a type defined in the WSDL's XSD schema, then that must be its only message part.
      • 3.5 soap:body.
        • If using document/literal binding and a message has a message part referencing a type defined in the WSDL's XSD schema then that part becomes the schema type of the enclosing SOAP envelope Body element.
    • Suds supports multiple message parts, each of which may be related either to an element or a type.
    • Suds uses message parts related to types, as if they were related to an element, using the message part name as the representing XML element name in the constructed related SOAP XML web service operation invocation request document.
    • WS-I Basic Profile 1.1 standard explicitly avoids the issue by stating the following:
      • R2204 - A document/literal binding in a DESCRIPTION MUST refer, in each of its soapbind:body element(s), only to wsdl:part element(s) that have been defined using the element attribute.
    • Rationale.
      • No other software has been encountered implementing the exact functionality specified in the WSDL 1.1 standard.
      • Already done in the original suds implementation.
      • Example software whose implementation matches our own.

WSDL XSD schema interpretation

  • minOccurs/maxOccurs attributes on all, choice & sequence schema elements are ignored.
    • Rationale.
      • Already done in the original suds implementation.
    • Extra notes.
      • SoapUI (tested with version 4.6.1).
        • For all, choice & sequence schema elements with their minOccurs attribute set to "0", does not explicitly mark elements found in such containers as optional.
  • Supports sending multiple same-named web service operation parameters, but only if they are specified next to each other in the constructed web service operation invocation request document.
    • Done by passing a list or tuple of such values to the suds constructed Python function representing the web service operation in question.
    • Rationale.
      • Already done in the original suds implementation.
    • Extra notes.
      • Such same-named values break other web service related tools as well, e.g. WSDL analyzer & invoker at http://www.validwsdl.com.

PROJECT IMPLEMENTATION NOTES

Sometimes we have a reason for implementing a feature in a certain way that may not be obvious at first and which thus deserves an implementation comment explaining the rationale behind it. In cases when such rationale would then be duplicated at different places in code, and project implementation note should be added and identified here, and its respective implementation locations marked using a comment such as:

# See 'Project implementation note #42'.

Project implementation note #1

pytest test parametrizations must be defined so they get ordered the same in different test processes.

Doing otherwise may confuse the pytest xdist plugin used for running parallel tests using multiple test processes (last tested using pytest 2.5.2, xdist 1.10 & execnet 1.2.0) and may cause it to exit with errors such as:

AssertionError: Different tests were collected between gw1 and gw0

Specifically, this means that pytest test parametrizations should not be constructed using iteration over unordered collections such as sets or dictionaries, at least not with Python's hash randomization feature enabled (implemented as optional since Python 2.6.8, enabled by default since Python 3.3).

See the following pytest issues for more detailed information:

  • #301 - serializing collection process (per host) on xdist to avoid conflicts/collection errors
  • #437 - different tests collected on two nodes with xdist

REPRODUCING PROBLEMATIC USE CASES

Failing web service processing examples can be easily packaged as reproducible test cases using the suds library 'message & reply injection' technique.

Some things you can achieve using this technique (for examples, see existing project unit tests):

  • Create a client object based on a fixed WSDL string.
  • Have a client object send a fixed request string without having it construct one based on the loaded WSDL schema and received arguments.
  • Have a client object process a fixed reply string without having it send a request to an actual external web service.