[openrtm-users 02820] Re: component is_activated() via service interface

[Ando Noriaki]

Hello,

At first, basic three states (inactive, active and error) belong
to ExecutionContext.  It means that an RTC A can be in Inactive
state on an ExecutionContext X while the RTC A might be in Active
state on an ExecutionContext Y.

But usually an RTC is associated with only one its own
ExecutionContext with ec_id=0.

If you can get the object reference of an RTC, you also can get
its ExecutionContextService object(s).  So an operation
RTC::ExecutionContext::get_component_state(in LightweightRTObject
comp ) is available.

http://www.openrtm.org/OpenRTM-aist/documents/IDLReference-en/interfaceRTC_1_1ExecutionContext.html#51a0396327ec0bab96f06a246032fc84

This is an example code.

 // -*- C++ -*-
 RTC::RTObject_var rtobj = obtaining object reference of an RTC anyway;
 RTC::ExecutionContextServiceList_var ecs = rtobj->get_owned_contexts();
 // ecs[0] is default context
 LifeCycleState state = ecs[0]->get_component_state(rtobj);
 // Now you can get state of the RTC :-)

But, the RTC might have one or more ExecutionContexts. In that
case, you have to investigate states of the RTC in each
ExecutionContext.

You can also know the state of an RTC through service ports if
the RTC has provided interfaces (provider) on it.
RTC::CorbaComsumer<> can be three states: nil, inactive, active.

http://www.openrtm.org/OpenRTM-aist/documents/current/cxx/classreference_en/classRTC_1_1CorbaPort.html#a1b9efe804a293b2c38a9cbe3b5ba54a0

- nil: Any object references are not assigned to this placeholder.
- active: an object reference is assigned and activated.
- inactive: an object reference is assigned but inactivated.

You can investigate whether the CorbaConsumer is nil by using
CORBA::is_nil().  Active or inactive object state can be
obtained by using "_non_existent()" function.

This knowledge can be obtained from CORBA's documentation.  The
best way is to read CORBA specifications which are available
from OMG website.

- http://www.omg.org/spec/CORBA
- http://www.omg.org/spec/CORBA/3.3/Interfaces/PDF

But these are huge specifications, so I prefer to read VisiBroker
programmers reference.

- http://techpubs.borland.com/am/bes/v5x/v51/en/vbprogrammersref.pdf
- http://techpubs.borland.com/am/bes/v5x/

Consequently, example code would be the following.

 RTC::ReturnCode_t MyServiceConsumer::onExecute(RTC::UniqueId ec_id)
 {
   try
     {
       if (CORBA::is_nil(m_myservice0._ptr()))
         {
           std::cout << "[nil] object reference is not assigned." << std::endl;
         }
       else
         {
           if (m_myservice0->_non_existent())
             {
               std::cout << "[inactive] provider is inactive." << std::endl;
             }
           else
             {
               std::cout << "[active] provider is active." << std::endl;
             }
         }
     }
   catch (...)
     {
       std::cout << "Unknown exception." << std::endl;
     }
   coil::sleep(1);
   return RTC::RTC_OK;
 }

Please try the example code. At first, activate the Consumer
component.  Before connecting service ports, the consumer state
would be "nil."  After connecting ports, the consumer state would
be "inactive", and after activating the Provider RTC the state
would be "active."

But if the provider RTC has one or more ExecutionContext, this
might be broken.That's an unresolved the design problem of the
OMG RTC specification and OpenRTM-aist implementation.


Best regards,
Noriaki Ando


--
Noriaki Ando, Ph.D.
    Senior Research Scientist, RT-Synthesis R.G., ISRI, AIST
    AIST Tsukuba Central 2, Tsukuba, Ibaraki 305-8568 JAPAN
    e-mail: n-ando ＠ aist.go.jp, web: http://staff.aist.go.jp/n-ando
    OpenRTM-aist: http://www.openrtm.org


2013/6/19 György Persa <persa ＠ sztaki.hu>:
> Hello everyone,
>
> In my project the order of components' activation is crucial. Meanwhile, we
> have an on-line tool for connecting components, which uses random order when
> activating components.
> Because of that, I'm looking for a function, which is able to decide whether
> the component(s) on the other end of a service port's interface is activated
> or not. Does such a function exists? If so, how to call it via an
> RTC::CorbaComsumer<> object, for instance?
> I've investigated the "SimpleService" example as well but couldn't find
> anything like this in the code. MyServiceConsumer doesn't check whether
> MyServiceProvider is active or not. It just uses try-catch blocks to
> identify inactive service provider.
>
> Thanks in advance,
> György Persa
>
>
> --
> Software engineer
> Computer and Automation Research Institute
> Hungarian Academy of Sciences
> Project VirCA, www.virca.hu
>
> _______________________________________________
> openrtm-users mailing list
> openrtm-users ＠ openrtm.org
> http://www.openrtm.org/mailman/listinfo/openrtm-users
>
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