Question on proper way to signal problem in IceBox start

Hi,

what is the proper way to signal an initialization problem on IceBox::Service::start? Checked the manual but couldn't really find any answers in there. According to the source code in case of an exception there will be a log message (and in case of an Ice::Exception the content of the exception will be logged as well).

Is there any specific exception that you recommend to throw in such a scenario (in case of my example this is a missing property required when configuring the IceBox service, right now I write a log message and simply issue a return - which for IceBox seems to signal that all is ok). So I would prefer to throw a meaningful exception in that case, ideally the chapter on IceBox should cover this.

So in my case imagine the following code snippet:

void MyServiceI::start(const std::string& name, 
const Ice::CommunicatorPtr& communicator, const Ice::StringSeq& args)
{
  if (communicator->getProperties()->getProperty("ImportantProperty").empty())  
  {
    throw Ice::WhichExceptionToThrow("ImportantPropertyNotSet");
  }

  _adapter = communicator->createObjectAdapter(name);
  _adapter->add(new MyFactoryI());  
  _adapter->activate();
}  

For convenience I attached the source of the relevant part in ServiceManagerI.cpp below.

cheers
Michael

    bool started = false;
    try
    {
        info.service->start(name, info.communicator == 0 ? _sharedCommunicator : info.communicator, info.args);
        started = true;
    }
    catch(const Ice::Exception& ex)
    {
        Warning out(_logger);
        out << "ServiceManager: exception in start for service " << info.name << ":\n";
        out << ex;
    }
    catch(...)
    {
        Warning out(_logger);
        out << "ServiceManager: unknown exception in start for service " << info.name;
    }
    
    {
        IceUtil::Monitor<IceUtil::Mutex>::Lock lock(*this);

        vector<ServiceInfo>::iterator p;
        for(p = _services.begin(); p != _services.end(); ++p)
        {
            if(p->name == name)
            {
                if(started)
                {
                    p->status = Started;

                    vector<string> services;
                    services.push_back(name);
                    servicesStarted(services, _observers);
                }
                else
                {
                    p->status = Stopped;
                }
                break;
            }
        }
        _pendingStatusChanges = false;
        notifyAll();

Hi,

You can throw an IceBox::FailureException:

if (communicator->getProperties()->getProperty("ImportantProperty").empty())  
{
    throw IceBox::FailureException(__FILE__, __LINE__, "invalid property");
}

Cheers,
Benoit.

Hi Benoit

thanks for your answer, so would you recommend FailureException as best practice is that scenario? I think the IceBox manual could use a short paragraph on the topic.

Thanks
Michael

grembo wrote: »

thanks for your answer, so would you recommend FailureException as best practice is that scenario? I think the IceBox manual could use a short paragraph on the topic.

Yes, using FailureException is the simplest solution. We'll update the manual accordingly.

Mark

Will do, thanks.

Just realized, that FailureException is actually defined and documented in IceBox.ice

/**
 *
 * An application service managed by a {@link ServiceManager}.
 *
 **/
local interface Service
{
    /**
     *
     * Start the service. The given communicator is created by the
     * {@link ServiceManager} for use by the service. This communicator may
     * also be used by other services, depending on the service
     * configuration.
     *
     * <p class="Note">The {@link ServiceManager} owns this communicator, and is
     * responsible for destroying it.
     *
     * @param name The service's name, as determined by the
     * configuration.
     *
     * @param communicator A communicator for use by the service.
     *
     * @param args The service arguments that were not converted into
     * properties.
     *
     * @throws FailureException Raised if {@link #start} failed.
     *
     **/
    void start(string name, Ice::Communicator communicator, Ice::StringSeq args);

    /**
     *
     * Stop the service.
     *
     **/
    void stop();
};

I will make sure to consult the individual documentation in slices as well in the future.