This is a work in progress and only for RTT 1.x !

Rationale

Problem: You want to pass custom types between distributed components, be able to see the value(s) of your custom type with in a deployer, and be able to read/write the custom type to/from XML files.

Solution: Develop two plugins that tell Orocos about your custom types.

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Assumptions

• The build directory is within the source directory. This helps with dynamic library loading.

Compatabilitry

Files

Overview

An RTT transport plugin provides methods to transport your custom types across CORBA, and hence between distributed Orocos components.

This is a multi-part example demonstrating plugins for two boost::posix_time types: ptime and time_duration.

• Part 1 Without the plugin creates components that use your custom type, and demonstrates that Orocos does not know anything about these types
• Part 2 Toolkit plugin demonstrates an Orocos plugin that makes the types available to Orocos. In a deployer, you can now see the values of your custom types
• Part 3 Transport plugin demonstrates an Orocos transport plugin making your custom types available across CORBA. Now you can pass types between deployers.
• TBD Part 4 will demonstrate XML manipulation
• TBD Part 5 will demonstrate accesors and manipulators for use in scripts and state machines

For additional information on plugins and their development, see [1].

Also, the KDL toolkit and transport plugins are good examples. See src/bindings/rtt in the KDL source.

Structure

.
|-- BoostToolkit.cpp
|-- BoostToolkit.hpp
|-- CMakeLists.txt
|-- config
|   |-- FindACE.cmake
|   |-- FindCorba.cmake
|   |-- FindOmniORB.cmake
|   |-- FindOrocos-OCL.cmake
|   |-- FindOrocos-RTT.cmake
|   |-- FindTAO.cmake
|   |-- UseCorba.cmake
|   `-- UseOrocos.cmake
|-- corba
|   |-- BoostCorbaConversion.hpp
|   |-- BoostCorbaToolkit.cpp
|   |-- BoostCorbaToolkit.hpp
|   |-- BoostTypes.idl
|   |-- CMakeLists.txt
|   `-- tests
|       |-- CMakeLists.txt
|       |-- corba-combined.cpp
|       |-- corba-recv.cpp
|       `-- corba-send.cpp
`-- tests
    |-- CMakeLists.txt
    |-- combined.cpp
    |-- no-toolkit.cpp
    |-- recv.cpp
    |-- recv.hpp
    |-- send.cpp
    `-- send.hpp

The toolkit plugin is in the root directory, with supporting test files in the tests directory.

CMake support files are in the config directory.

The transport plugin is in the corba directory, with supporting test files in the corba/tests directory.

Limitations

• Show how to write a plugin telling Orocos about your custom types
• Show how to write a transport plugin allowing Orocos to move your custom types between deployers/processes.
• Demonstrate how to test said plugins.
• Use either ACE/TAO or OmniORB for CORBA support

Currently, this example does not yet

• Show how to read/write the custom types to/from XML file
• Provide manipulators and/or accessors of your custom types, that can be used in scripts and state machines.
• Does not demonstrate testing of the CORBA transport plugin within a single deployer, using two components. An optimization in RTT bypasses the CORBA mechanism in this case, rendering the test useless.
• Does not deal with all intricacies of the boost types (eg all of the special values).

NB I could not find a method to get at the underlying raw 64-bit or 96-bit boost representation of ptime. Hence, the transport plugin inefficiently transports a ptime type using two separate data values. If you know of a method to get at the raw representation, I would love to know. Good luck in template land ...

References