Consider binaries to implement the functionality offered by gz

[osrf-migration]

Original report (archived issue) by Carlos Agüero (Bitbucket: caguero, GitHub: caguero).

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Right now, ign is a ruby script that offers several subcommands (topic, msg, etc.). Each subcommand is implemented by a function inside a versioned Ignition shared library. ign also keeps track of multiple versions of the same library. This approach has some issues, in particular we have detected:

1. Difficulty for using gdb when running ign. Imagine for example running ign gazebo …
2. Portability issues. E.g.: On Windows, there are ABI problems interacting from Ruby (compiled with MinGW) and an Ignition shared library (compiled with Visual Studio).

An idea for mitigating these issues might be to move the functionality from a shared library to a binary (e.g.: igntopic). In this case, ign should invoke the right external binary. The solution to (1) is to run gdb with the binary directly without using ign. (2) probably won’t happen again as we wouldn’t need to interact with a shared library anymore, just executing an external binary which looks less involved.

On the other hand, each Ignition library should do some refactor and expose a binary (or a collection of binaries) that capture all functionality to be executed from the command line.

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[chapulina]

ign-tools itself should not be limited to loading shared libraries right now. This is being done at each library's Ruby file, for example cmdtransport.rb.in.

To use executables in ign-transport for example, one would need to:

• Install executables that provide the command line functionality, like topic and service
• Call those from the Ruby script instead of loading a shared lib
• It may be interesting to move the command line argument parsing from Ruby to the executables

[scpeters]

ign-tools itself should not be limited to loading shared libraries right now. This is being done at each library's Ruby file, for example cmdtransport.rb.in.

To use executables in ign-transport for example, one would need to:

• Install executables that provide the command line functionality, like topic and service
• Call those from the Ruby script instead of loading a shared lib
• It may be interesting to move the command line argument parsing from Ruby to the executables

we are doing this in gazebosim/gz-transport#216 using the cli component of ign-utils

[chapulina]

Let's close this issue once all libraries have migrated to binaries.

[chapulina]

• ign-transport
  • Add standalone executables gz-transport#216
  • Add standalone executable for ign-transport-log command gz-transport#247
• ign-msgs
• ign-gui
  • Add standalone executable gz-gui#250
• ign-launch
  • Add standalone executables gz-launch#121
• ign-gazebo
  • Standalone Ignition Gazebo executables gz-sim#694
• ign-fuel-tools
• ign-plugin
  • Add standalone executable for ign-plugin-info command gz-plugin#54
  • Added standalone executable gz-plugin#65
• sdformat
  • WIP: Implement gz sdf as standalone executable sdformat#1465

[traversaro]

2\. Portability issues. E.g.: On Windows, there are ABI problems interacting from Ruby (compiled with MinGW) and an Ignition shared library (compiled with Visual Studio).

I guess anyone that tried this on Windows know this, but just to record this for future readers: another problem that is present in Windows when using shell such as Command Prompt or Powershell is that bash-based shebangs do not work, so even if ign.rb is part of the path, just typing ign does not execute any command, and you need to run ruby %CONDA_PREFIX%\Library\bin\ign.rb or something like that.

[traversaro]

2\. Portability issues. E.g.: On Windows, there are ABI problems interacting from Ruby (compiled with MinGW) and an Ignition shared library (compiled with Visual Studio).

I guess anyone that tried this on Windows know this, but just to record this for future readers: another problem that is present in Windows when using shell such as Command Prompt or Powershell is that bash-based shebangs do not work, so even if ign.rb is part of the path, just typing ign does not execute any command, and you need to run ruby %CONDA_PREFIX%\Library\bin\ign.rb or something like that.

For historical reference, that was eventually fixed in #73 .

[sauk2]

@azeey I would like to work on this issue!

[scpeters]

@azeey I would like to work on this issue!

As a starting point, I would recommend porting the fix from gazebosim/gz-plugin#131 to other libraries that already have standalone executable commands like gz-transport and gz-launch. If the windows tests just work after that fix, I would say enable them, but if there's a bunch of failures I think it's worth merging the fix to the ruby file on its own.

A follow up task could be completing the conversion for gz sdf that is in progress in gazebosim/sdformat#1465.

What do you think @azeey?