use new type identification for service calls

[Karsten1987]

Similar problem as described here: #241
ros2 service call ... fails because the new service types are parsed incorrectly.

Signed-off-by: Karsten Knese karsten@openrobotics.org

[dirk-thomas]

Why not just (without error checking)?

parts = service_type.split('/')
module = importlib.import_module('.'.join(parts[:-1]))
srv_module = getattr(module, parts[-1])

[Karsten1987]

I don't have enough insights about this to answer whether or not the error checking makes sense or not. I'd naively say yes (error checking makes sense) so that we catch easier when this behavior changes in the future, but I am open for whatever is best practice here.

[jacobperron]

I think more generally having what @dirk-thomas suggests makes sense, since we haven't settle on how many parts to the message namespace there can be. Probably a better way to error check is to wrap the whole thing in a try-except since the import_module / getattr should tell us if the name is valid, right?

[Karsten1987]

@dirk-thomas is the proposed way what you envisioned? I am happy to change it to whatever is recommended.

[dirk-thomas]

My snippet was meant as this-is-how-the-logic-should-work and would get rid of all the extra steps currently being used. The snippet doesn't do any error checking - but the actual patch should certainly do that - I just left that out for brevity.

[Karsten1987]

@jacobperron @dirk-thomas does 468289d look like what you've suggested?

[dirk-thomas]

LGTM.

Have you ensure that it continues to work for actions?

[Karsten1987]

Did it work before this patch with actions? I haven't tested it with actions. Do we have a working example for this?

[dirk-thomas]

I assume it worked before. Since you are changing the code dealing with action types in this patch please also check it with an action type. I don't have an example at hand.

[Karsten1987]

How do we get the type information of the actual action service?
Let's say I run:

ros2 run examples_rclcpp_minimal_action_server action_server_member_functions

what's the respective type to the service:

ros2 service call /fibonacci/_action/send_goal <type> "{order: 10}"

I've tried:

ros2 service call /fibonacci/_action/send_goal example_interfaces/action/Fibonacci_SendGoal_Request "{order: 10}"

but this fails with AttributeError: module 'example_interfaces.action' has no attribute 'Fibonacci_SendGoal_Request'. This makes me believe that the split logic works correctly, but I've specified the wrong type.

[jacobperron]

The "send goal" service is defined in the module example_interfaces.action._fibonacci. Even with the code before, I don't think it is possible to make the service call work for actions. But maybe now with multiple namespaces allowed, it could be possible with something like:

ros2 service call /fibonacci/_action/send_goal example_interfaces/action/_fibonacci/Fibonacci_SendGoal "{goal: {order: 10}}"

[Karsten1987]

Great! @jacobperron example does work.

[Karsten1987]

CI (build: --packages-up-to ros2service | test: --packages-select ros2service)

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