--------------------                    
,------------------.                         ,---------------.
|SurveyManager     |                         |SurveyAttribute|
|------------------|  ,------------------.   |---------------|
|+getInstance()    |  |SurveyVerifyResult|   |+field         |
|+loadCacheSurvey()|  |------------------|   |+mandatory     |
|+createSurvey()   |--|+isValid          |   |+type          |
|+verifySurvey()   |  |+invalidAttributes|   |+value         |
|+saveSurvey()     |  `------------------'   |+valueType     |
|+submitSurvey()   |                         |+valueValidator|
`------------------'                         |+valueDefault  |
                                             `---------------'