[IGSTK-Users] Error handling in igstk applications

[Ziv Yaniv]

Hi Torleif,

Yes. I usually do this in the constructor.

              Ziv

Torleif Sandnes wrote:
> Thanks Ziv, this seems to be a good solution to my problem.
> 
> In addition to funneling the events to a single state, I will have to 
> add lines like the following:
> 
> "igstkcomponent->AddObserver(theEvent, myErrorObserver);"
> 
> for each event I want to handle, right?
> 
> Regards,
> Torleif
> 
>> Hi Torleif,
>>
>> You can have all these events transition to a single error state and 
>> provide the user with an appropriate error message using a map between 
>> event and message. Attached is a class that uses this approach. Note 
>> that it does not follow the igstk state machine approach but is an 
>> example of how to use a map to get the functionality you want.
>>
>>             hope this helps
>>                    Ziv
>>
>> Torleif Sandnes wrote:
>>> Hi.
>>> I am building an application that has to read Dicom images and want 
>>> to listen for all error events that the imagereader can send. Based 
>>> on the error, I want to provide a message to the user describing the 
>>> error.
>>> Using igstkEventTransductionMacro, I could add a state to my 
>>> imagereader component for every errorevent from igstk::DicomImageReader:
>>>    DICOMInvalidRequestErrorEvent
>>>    DICOMImageDirectoryEmptyErrorEvent
>>>    DICOMImageDirectoryDoesNotExistErrorEvent
>>>    DICOMImageDirectoryIsNotDirectoryErrorEvent
>>>    DICOMImageDirectoryDoesNotHaveEnoughFilesErrorEvent
>>>    DICOMImageSeriesFileNamesGeneratingErrorEvent
>>>    DICOMImageReadingErrorEvent
>>> This would introduce seven new states and (at least) seven new 
>>> transitions. All I want to do with these events is to convert it into 
>>> a message to the user, so each transition's processing method would 
>>> do essentially the same thing. This seems to be adding a lot of 
>>> complexity to my statemachine to accomplish just a little.
>>> Ideally, I would like to add only one "imagereading failed" state to 
>>> my component and be able to differentiate between the events. Is this 
>>> possible?
>>> Regards,
>>> Torleif Sandnes
>>> Sintef Health Research
>>> _______________________________________________
>>> IGSTK-Users mailing list
>>> IGSTK-Users at public.kitware.com
>>> http://public.kitware.com/cgi-bin/mailman/listinfo/igstk-users
>>
>>
>> --Ziv Yaniv, PhD., Research Assistant Professor
>> Imaging Science and Information Systems (ISIS) Center
>> Department of Radiology
>> Georgetown University Medical Center
>> 2115 Wisconsin Avenue, Suite 603
>> Washington, DC, 20007,
>>
>> Phone: +1-202-687-7286
>> Fax: +1-202-784-3479
>> email: zivy at isis.imac.georgetown.edu
>> web: http://isiswiki.georgetown.edu/zivy/
>> #ifndef _IGSTK_ERROR_OBSERVER_H_
>> #define _IGSTK_ERROR_OBSERVER_H_
>>
>> /************************************************************************** 
>>
>> * Copyright (c) 2007
>> * Computer Aided Interventions and Medical Robotics (CAIMR) group,
>> * Imaging Science and Information Systems (ISIS) research center,
>> * Georgetown University.
>> *
>> * All rights reserved.
>> *
>> * Permission to use, copy, modify, distribute, and sell this software
>> * and its documentation for any purpose is hereby granted without fee,
>> * provided that:
>> * (1) Redistributions of source code must retain the above copyright 
>> notice,
>> *     this list of conditions and the following disclaimer.
>> * (2) Redistributions in binary form must reproduce the above 
>> copyright notice,
>> *     this list of conditions and the following disclaimer in the 
>> documentation
>> *      and/or other materials provided with the distribution.
>> * (3) The author's name may not be used to endorse or promote products 
>> derived
>> *     from this software without specific prior written permission.
>> * (4) Modified source versions must be plainly marked as such, and 
>> must not be
>> *     misrepresented as being the original software.
>> *
>> * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER ``AS IS'' AND ANY 
>> EXPRESS
>> * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 
>> WARRANTIES
>> * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
>> * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 
>> INCIDENTAL,
>> * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 
>> LIMITED TO,
>> * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 
>> PROFITS;
>> * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF 
>> LIABILITY,
>> * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
>> * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN 
>> IF ADVISED
>> * OF THE POSSIBILITY OF SUCH DAMAGE.
>> **************************************************************************/ 
>>
>>
>> #include <itkCommand.h>
>> #include <itkSmartPointer.h>
>> #include <igstkMacros.h>
>>
>> /**
>>  * This class serves a similar function as the errno variable and 
>> perror error printing function.
>>  * It is an adaptor between the IGSTK event driven error reporting and 
>> exception throwing as
>>  * used in standard C++.
>>  *
>>  * After each call to RequestXXX() on a IGSTK component the user 
>> should check if an error occured,
>>  * using the observer's boolean Error() method, get the associated 
>> error message using the observer's
>>  * GetErrorMessage() method, and then clear the error using the 
>> ClearError() method.
>>  *
>>  * @author Ziv Yaniv
>>  *
>>  */
>> class IGSTKErrorObserver : public itk::Command
>> {
>> public:
>>   typedef IGSTKErrorObserver               Self;
>>   typedef ::itk::Command                   Superclass;
>>   typedef ::itk::SmartPointer<Self>        Pointer;
>>   typedef ::itk::SmartPointer<const Self>  ConstPointer;
>>
>>   igstkNewMacro(Self)
>>   igstkTypeMacro(IGSTKErrorObserver, itk::Command)
>>
>>   /**
>>    * When an error occurs in an IGSTK component it will invoke this 
>> method with the appropriate
>>    * error event object as a parameter.
>>    */
>>   virtual void Execute(itk::Object *caller, const itk::EventObject & 
>> event) throw (std::exception);
>>   /**
>>    * When an error occurs in an IGSTK component it will invoke this 
>> method with the appropriate
>>    * error event object as a parameter.
>>    */
>>   virtual void Execute(const itk::Object *caller, const 
>> itk::EventObject & event) throw (std::exception);
>>   /**
>>    * Clear the current error.
>>    */
>>   void ClearError() {this->errorOccured = false; 
>> this->errorMessage.clear();}
>>   /**
>>    * If an error occurs in one of the observed IGSTK components this 
>> method will return true.
>>    */
>>   bool Error() {return this->errorOccured;}
>>   /**
>>    * Get the error message associated with the last IGSTK error.
>>    */
>>   void GetErrorMessage(std::string &errorMessage) {errorMessage = 
>> this->errorMessage;}
>>
>> protected:
>>
>>   /**
>>    * Construct an error observer for all the possible errors that 
>> occur in IGSTK components
>>    * used in the DataAcqusition class.
>>    */
>>   IGSTKErrorObserver();
>>   virtual ~IGSTKErrorObserver(){}
>> private:
>>   bool errorOccured;
>>   std::string errorMessage;
>>   std::map<std::string,std::string> errorEvent2ErrorMessage;
>>
>>                //purposely not implemented
>>   IGSTKErrorObserver(const Self&);
>>   void operator=(const Self&);
>> };
>>
>> #endif //_IGSTK_ERROR_OBSERVER_H_
>> #include "IGSTKErrorObserver.h"
>> #include <igstkTracker.h>
>> #include <igstkEvents.h>
>>
>> IGSTKErrorObserver::IGSTKErrorObserver() : errorOccured(false)
>> {                              //serial communication errors
>>   
>> this->errorEvent2ErrorMessage.insert(std::pair<std::string,std::string>(igstk::OpenPortErrorEvent().GetEventName(),"Error 
>> opening com port."));
>>   
>> this->errorEvent2ErrorMessage.insert(std::pair<std::string,std::string>(igstk::ClosePortErrorEvent().GetEventName(),"Error 
>> closing com port."));
>>                               //tracker errors
>>   
>> this->errorEvent2ErrorMessage.insert(std::pair<std::string,std::string>(igstk::TrackerOpenErrorEvent().GetEventName(),"Error 
>> opening tracker communication."));
>>   
>> this->errorEvent2ErrorMessage.insert(std::pair<std::string,std::string>(igstk::TrackerInitializeErrorEvent().GetEventName(),"Error 
>> initializing tracker."));
>>   
>> this->errorEvent2ErrorMessage.insert(std::pair<std::string,std::string>(igstk::TrackerStartTrackingErrorEvent().GetEventName(),"Error 
>> starting tracking."));
>>   
>> this->errorEvent2ErrorMessage.insert(std::pair<std::string,std::string>(igstk::TrackerStopTrackingErrorEvent().GetEventName(),"Error 
>> stopping tracking."));
>>   
>> this->errorEvent2ErrorMessage.insert(std::pair<std::string,std::string>(igstk::TrackerUpdateStatusErrorEvent().GetEventName(),"Error 
>> getting data from tracker."));
>>   
>> this->errorEvent2ErrorMessage.insert(std::pair<std::string,std::string>(igstk::TrackerCloseErrorEvent().GetEventName(),"Error 
>> closing tracker communication."));
>>   
>> this->errorEvent2ErrorMessage.insert(std::pair<std::string,std::string>((igstk::TrackerUpdateStatusErrorEvent()).GetEventName(),"Error 
>> updating transformations from tracker."));
>> }
>> /*****************************************************************************/ 
>>
>> void IGSTKErrorObserver::Execute(itk::Object *caller, const 
>> itk::EventObject & event) throw (std::exception)
>> {
>>   std::map<std::string,std::string>::iterator it;
>>   std::string className = event.GetEventName();
>>   it = this->errorEvent2ErrorMessage.find(className);
>>                //listening to an event that wasn't entered into the 
>> map of events we listen to
>>   if(it == this->errorEvent2ErrorMessage.end()) {
>>     std::string logicalErrorMessage = std::string("ErrorObserver: 
>> listening to an event (") + className + std::string(") which is not 
>> one of the expected events.");
>>     throw std::exception(logicalErrorMessage.c_str());
>>   }
>>   this->errorOccured = true;
>>   this->errorMessage = (*it).second;
>> }
>> /*****************************************************************************/ 
>>
>> void IGSTKErrorObserver::Execute(const itk::Object *caller, const 
>> itk::EventObject & event) throw (std::exception)
>> {
>>   const itk::Object * constCaller = caller;
>>   this->Execute(constCaller, event);
>> }
> 
> 
> 
> 


-- 
Ziv Yaniv, PhD., Research Assistant Professor
Imaging Science and Information Systems (ISIS) Center
Department of Radiology
Georgetown University Medical Center
2115 Wisconsin Avenue, Suite 603
Washington, DC, 20007,

Phone: +1-202-687-7286
Fax: +1-202-784-3479
email: zivy at isis.imac.georgetown.edu
web: http://isiswiki.georgetown.edu/zivy/