Building and Distributing Bundles

A bundle is a collection of code and data that can be added to ChimeraX to provide support for new graphical tools, commands, file formats, web databases and selection specifiers. This document describes the details of how to create a bundle and publish it in the ChimeraX toolshed. There is also a step-by-step example of writing a bundle available here.

Bundle Format

A ChimeraX bundle is packaged as a Python wheel.

A wheel usually contains Python and/or compiled code along with additional resources such as icons, data files, and documentation. While the general Python wheel specification supports installing files into arbitrary location, ChimeraX bundles are limited to provide a single folder/directory, which may be installed using the toolshed install command. Bundle folders are typically placed in a per-user location, which may be listed using the toolshed cache command.

It is possible but not recommended to use pip to install a bundle. ChimeraX maintains a bundle metadata cache for fast initialization, which pip will not update, and therefore the bundle functionality may not be available even though the wheel is installed. In this event, try running the toolshed refresh command to force an update.

Creating bundles follows the same basic procedure as creating Python wheel, with a few ChimeraX customizations. The most straightforward way is to start with some ChimeraX sample code and modify it appropriately.

Bundle Sample Code

To build a bundle from the sample code (XML configuration / TOML configuration ), you can either use the make program, or the ChimeraX application if you do not have make. On Linux and macOS, make is available as part of the developer package. On Windows, make is available as part of Cygwin.

Because the sample code includes C++ source code that need to be compiled, you will need a C++ compiler for the build. On Windows, we use Microsoft Visual Studio, Community 2015. On the Mac, we use Xcode. On Linux, gcc and g++ are available in different packages depending on the flavor of Linux.

The sample code is organized with “administrative” code at the top level and actual bundle code in the src folder. Administrative code, with the exception of license text, is only used for building the bundle. All other contents of the bundle should be in src.

Administrative Files

Makefile is the configuration file used by the make command. This file is not used if you use the devel command to build and install your bundle.)

README contains a pointer back to this document.

bundle_info.xml is an XML file containing information about the bundle, including its name, version, dependencies, etc. This file is used when you use the devel command to build and install your bundle.

license.txt.bsd and license.txt.mit are two sample license text files. The actual file used when building the bundle is license.txt which must exist. For testing, simply renaming one of the sample license text file is sufficient. You may want to use a custom license for your actual bundle.

setup.py.in contains Python code for building the bundle. This file is a remnant from when bundles were built using the Python interpreter instead of ChimeraX It is here only as a potential starting point for developers who need greater control over the build process.

setup.cfg is the configuration file used when setup.py is run. This file should not be modified.

Bundle Source Code Files

__init__.py contains the bundle initialization code. Typically, it defines a subclass of the chimerax.core.toolshed.BundleAPI class and instantiates a single instance named bundle_api. ChimeraX communicates with the bundle through this singleton, which must conform to the bundle API.

cmd.py contains code called by bundle_api from __init__.py for executing the sample command. Before deciding on the name and syntax of your own command, you should look at the command style guide.

io.py contains code called by bundle_api from __init__.py for opening XYZ files.

tool.py contains code called by bundle_api from __init__.py for starting the graphical interface.

_sample_pyapi.cpp and _sample_pybind11.cpp contain sample C++ code that demonstrate two possible ways of binding C++ to Python. Thye compile into Python modules that each define two module functions. Which binding gets used at runtime is determined by the api argument of the sample command.

Bundle Help Files

This sample bundle does not provide any help files, but if it did they would be provided as HTML files under a src/docs folder. Inside that folder documentation intended for developers should be in a devel subfolder and documentation for users in a user subfolder. Specifically, documentation for commands should be under user/commands as described here, and documentation for tools under user/tools as described here. The docs directory also needs to be added to the list of data files in bundle_info.xml.

Building and testing the Sample Bundle using ``ChimeraX``

1. Create a license.txt file. The easiest way is to copy license.txt.bsd to license.txt.

2. Start ChimeraX. In the command line, type devel install pathname where pathname is the path to the folder containing your bundle. This will build a wheel from your bundle and install it as a user bundle, i.e., it will not be installed in the user-specific folder rather than the ChimeraX folder.

3. Check that the bundle works by opening a molecule and executing the command sample count. It should report the number of atoms and bonds for each molecule in the log.

Building the Sample Bundle using ``make``

1. Edit Makefile and change CHIMERAX_APP to match the location of ChimeraX.app on your system.

2. Create a license.txt file. The easiest way is to copy license.txt.bsd to license.txt.

3. Execute make install (which simply executes devel install . in ChimeraX).

4. Check directory dist to make sure the wheel was created.

5. Check that the bundle works by opening a molecule and executing the command sample count. It should report the number of atoms and bonds for each molecule in the log.

Customizing the Sample Code

To convert the sample code into your own bundle, there are several importants steps:

1. First, customize the source code in the src folder for your bundle.

2. Edit bundle_info.xml to update bundle information. The supported elements are listed below in Bundle Information XML Tags.

Building and Testing Bundles

To build and test your bundle, execute the following command (or run make install which invokes the same command):

$(CHIMERAX_EXE) --nogui --cmd "devel install . ; exit"

Execute the devel install . command in ChimeraX. Python source code and other resource files are copied into the build folder. C/C++ source files, if any, are compiled and also copied into the build folder. The files in build are then assembled into a wheel in the dist directory. The assembled wheel is installed as a user bundle.

Note that on Windows $(CHIMERAX_EXE) uses the ChimeraX-console.exe executable rather than the normal ChimeraX.exe. This is because on Windows an executable cannot be both a GUI and a console app. So for running ChimeraX with the --nogui flag, you need to use the console executable.

If the command completes successfully, fire up ChimeraX (make test is a shortcut if make is available) and try out your command. Warning and error messages should appear in the Log window. If the bundle is not working as expected, e.g., command is not found, tool does not start, and no messages are being displayed, try executing $(CHIMERAX_EXE) --debug (or make debug for short), which runs ChimeraX in debugging mode, and see if more messages are shown in the console.

Distributing Bundles

With ChimeraX bundles being packages as standard Python wheel-format files, they can be distributed as plain files and installed using the ChimeraX toolshed install command. Thus, electronic mail, web sites and file sharing services can all be used to distribute ChimeraX bundles.

Private distributions are most useful during bundle development, when circulation may be limited to testers. When bundles are ready for public release, they can be published on the ChimeraX Toolshed, which is designed to help developers by eliminating the need for custom distribution channels, and to aid users by providing a central repository where bundles with a variety of functionality may be found.

Customizable information for each bundle on the toolshed includes its description, screen captures, authors, citation instructions and license terms. Automatically maintained information includes release history and download statistics.

To submit a bundle for publication on the toolshed, you must first sign in. Currently, only Google sign in is supported. Once signed in, use the Submit a Bundle link at the top of the page to initiate submission, and follow the instructions. The first time a bundle is submitted to the toolshed, approval from ChimeraX staff is needed before it is published. Subsequent submissions, using the same sign in credentials, do not need approval and should appear immediately on the site.

Cleaning Up ChimeraX Bundle Source Folders

Two make targets are provided for removing intermediate files left over from building bundles:

make clean

Remove generated files, e.g., setup.py and build folder, as well as the dist folder containing the built wheels.

Bundle Information XML Tags

ChimeraX bundle information is stored in bundle_info.xml. Details of supported XML tags are found in Bundle Information XML Tags.

Using pyproject.toml for Bundles

ChimeraX bundle information can optionally be stored in pyproject.toml. Details of that file are found in Using pyproject.toml for Bundles