Move the ReaderWriterFactory to the rosbag2_cpp layer

[MichaelOrlov]

Description

Move the ReaderWriterFactory to the rosbag2_cpp layer

Currently the ReaderWriterFactory is part of the rosbag2_transport package and part of its namespace.
However, the ReaderWriterFactory doesn't have any dependencies from the rosbag2_transport package.
It will be more appropriate if the ReaderWriterFactory will be located at the rosbag2_cpp package.

Related Issues

• Feature request: rosbag2 reader that automatically detects if the bagfile is compressed or not #1677
• Use the ReaderWriterFactory to construct a bagfile reader ros2_documentation#4499

Completion Criteria

• The ReaderWriterFactory moved to the rosbag2_cpp layer and all dependencies in the rosbag2 updated.

Implementation Notes / Suggestions

Since this is an API-breaking change, we can't just move ReaderWriterFactory from the rosbag2_transport namespace to the rosbag2_cpp. Instead, need to add a deprecation flag to the rosbag2_transport::ReaderWriterFactory and add a new rosbag2_cpp::ReaderWriterFactory.

Testing Notes / Suggestions

Move relevant tests if they exist from the rosbag2_transport layer to the rosbag2_cpp layer.

[Jeffxzj]

Kindly asked is there anyone working on this issue ? If not, i am glad to undertake it. @MichaelOrlov

[MichaelOrlov]

@Jeffxzj Thank you for being willing to help with this task.
No one has taken it so far. Feel free to take it.

[Jeffxzj]

@MichaelOrlov It seems that ReaderWriterFactory still depends on the rosbag2_transport package. The rosbag2_transport::ReaderWriterFactory::make_writer API needs the rosbag2_transport::RecordOptions & record_options as its parameter. Since we need to keep the deprecated rosbag2_transport::ReaderWriterFactory::make_writer API, the rosbag2_transport still needs to depend on the rosbag2_cpp package. Therefore, adding rosbag2_transport to the rosbag2_cpp 's package dependencies when moving the make_writer API can cause circular dependency error when colcon build.

[MichaelOrlov]

Hi @Jeffxzj,
The way how I envision a solution to break this cyclic dependency is the following

1. Will need to create a duplicate of the CompressionOptions struct in the rosbag2_cpp package and name it as WriterOptions.
2. Use rosbag2_cpp::WriterOptions as the input parameter for the

   rosbag2_cpp::ReaderWriterFactory::make_writer(const rosbag2_cpp::WriterOptions & writer_options)

3. Copy values from the writer_options to the rosbag2_compression::CompressionOptions compression_options inside ReaderWriterFactory::make_writer(..)

Edit:
I'm sorry, but it will not help. In the end, we will still have cyclic dependencies between rosbag2_cpp and rosbag2_compression.

[MichaelOrlov]

• To avoid cyclic dependencies between rosbag2_cpp and rosbag2_compression, the ReaderWriterFactory should be somewhere outside of the rosbag2_cpp package.
• It seems that currently, due to the aforementioned cyclic dependencies, there is no better place for the ReaderWriterFactory rather than the rosbag2_transport package. Therefore, I am closing this task as it wouldn't be done.