TAO下IDL結構定義編譯文件分析2005-09-21 lwx
每個IDL的定義的結構經過TAOIDL編譯器編譯將生成一些結構編碼的函數的定義。主要分爲TypeCode的處理函數和Any的處理函及其CDR編碼的處理。由結構到Any的流化和解析，析構，及其結構與TypedCode處理組成。結構到Any類型是通過TAO的內部模板TAO::Any_Dual_Impl_T來實現。結構流編碼通過TAO_OutputCDR,TAO_inputCDR.
IDL定義如下
// 告警信息定義
struct AlarmInfo {
GeneralizedTime eventTime;
ObjectInstance source;
ObjectClass sourceClass;
NotificationIdentifier notificationId;
CorrelatedNotifications alarmInfoCorrelatedNotifications;
ProbableCause alarmInfoProbableCause;
SpecificProblems alarmInfoSpecificProblems;
PerceivedSeverity alarmInfoPerceivedSeverity;
boolean backedUpStatus;
ObjectInstance backUpObject;
TrendIndication alarmInfoTrendIndication;
ThresholdInfo alarmInfoThresholdInfo;
AttributeChangeList stateChangeDefinition;
AttributeList monitoredAttributes;
ProposedRepairActions alarmInfoProposedRepairActions;
AdditionalString additionalText;
AdditionalInformation additionalInfo;
};
編譯生成的文件*C.h/cpp
struct AlarmInfo
{
typedef AlarmInfo_var _var_type;
static void _tao_any_destructor (void *);
TAO_String_Manager eventTime;
nms::ObjectInstance source;
nms::ObjectClass sourceClass;
nms::NotificationIdentifier notificationId;
nms::CorrelatedNotifications alarmInfoCorrelatedNotifications;
nms::ProbableCause alarmInfoProbableCause;
nms::SpecificProblems alarmInfoSpecificProblems;
nms::PerceivedSeverity alarmInfoPerceivedSeverity;
CORBA::Boolean backedUpStatus;
nms::ObjectInstance backUpObject;
nms::TrendIndication alarmInfoTrendIndication;
nms::ThresholdInfo alarmInfoThresholdInfo;
nms::AttributeChangeList stateChangeDefinition;
nms::AttributeList monitoredAttributes;
nms::ProposedRepairActions alarmInfoProposedRepairActions;
TAO_String_Manager additionalText;
nms::AdditionalInformation additionalInfo;
};
Ø 1 裏面包含一個靜態成員函數是析構AlarmInfo指針內存空間
void
nms::AlarmInfo::_tao_any_destructor (
void *_tao_void_pointer
)
{
AlarmInfo *_tao_tmp_pointer =
ACE_static_cast (AlarmInfo *, _tao_void_pointer);
delete _tao_tmp_pointer;
}
在CPP還定義的Typdecode的函數，並設置函數指針
static CORBA::TypeCode _tc_TAO_tc_nms_AlarmInfo (
CORBA::tk_struct,
sizeof (_oc_nms_AlarmInfo),
(char *) &_oc_nms_AlarmInfo,
0,
sizeof (nms::AlarmInfo)
);
namespace nms
{
::CORBA::TypeCode_ptr _tc_AlarmInfo =
&_tc_TAO_tc_nms_AlarmInfo;
}
Ø 2 定義AlarmInfo 到的Any析構的函數
void
nms::AlarmInfo::_tao_any_destructor (
void *_tao_void_pointer
)
{
AlarmInfo *_tao_tmp_pointer =
ACE_static_cast (AlarmInfo *, _tao_void_pointer);
delete _tao_tmp_pointer;
}
Ø 3 結構對象AlarmInfo放入Any的打包
void operator<<= (
CORBA::Any &_tao_any,
const nms::AlarmInfo &_tao_elem
)
{
TAO::Any_Dual_Impl_T<nms::AlarmInfo>::insert_copy (
_tao_any,
nms::AlarmInfo::_tao_any_destructor,
nms::_tc_AlarmInfo,
_tao_elem
);
}
Ø 4 結構對象AlarmInfo從Any的解析出來
// Extraction to non-const pointer (deprecated).
CORBA::Boolean operator>>= (
const CORBA::Any &_tao_any,
nms::AlarmInfo *&_tao_elem
)
{
return _tao_any >>= ACE_const_cast (
const nms::AlarmInfo *&,
_tao_elem
);
}
Ø 結構與TAO內部的實現類的關係
TAO::Any_Dual_Impl_T<nms::AlarmInfo>::insert_copy (…)
具體的結構到Any的模板實現類，放入insert，吸取extract，結構對象指針value，編碼，解碼。
template<typename T>
class Any_Basic_Impl_T : public Any_Impl
{
public:
Any_Basic_Impl_T (CORBA::TypeCode_ptr,
const T & val);
virtual ~Any_Basic_Impl_T (void);
static void insert (CORBA::Any &,
CORBA::TypeCode_ptr,
const T &);
static CORBA::Boolean extract (const CORBA::Any &,
CORBA::TypeCode_ptr,
T &);
virtual CORBA::Boolean marshal_value (TAO_OutputCDR &);
CORBA::Boolean demarshal_value (TAO_InputCDR &);
virtual void _tao_decode (TAO_InputCDR &
ACE_ENV_ARG_DECL_WITH_DEFAULTS);
virtual const void *value (void) const;
static Any_Basic_Impl_T<T> *create_empty (CORBA::TypeCode_ptr);
private:
T value_;
};
Ø 在編譯的IDL的文件中產生了一個*C.i的文件，該文件主要是將定義的數據結構類型流化到CDR的對象中，及其從CDR流中解析出來。
Ø 結構到ANY的操作符
void operator<<= (CORBA::Any &, const nms::AlarmInfo &); // copying version
void operator<<= (CORBA::Any &, nms::AlarmInfo*); // noncopying version
CORBA::Boolean operator>>= (const CORBA::Any &, nms::AlarmInfo *&); // deprecated
CORBA::Boolean operator>>= (const CORBA::Any &, const nms::AlarmInfo *&);
Ø 結構到CDR的流化和解碼處理
CORBA::Boolean operator<< (TAO_OutputCDR &, const nms::AlarmInfo &);
CORBA::Boolean operator>> (TAO_InputCDR &, nms::AlarmInfo &);
流化成CDR格式的流
ACE_INLINE
CORBA::Boolean operator<< (
TAO_OutputCDR &strm,
const nms::AlarmInfo &_tao_aggregate
)
{
return
(strm << _tao_aggregate.eventTime.in ()) &&
(strm << _tao_aggregate.source) &&
(strm << _tao_aggregate.sourceClass) &&
(strm << _tao_aggregate.notificationId) &&
(strm << _tao_aggregate.alarmInfoCorrelatedNotifications) &&
(strm << _tao_aggregate.alarmInfoProbableCause) &&
(strm << _tao_aggregate.alarmInfoSpecificProblems) &&
(strm << _tao_aggregate.alarmInfoPerceivedSeverity) &&
(strm << CORBA::Any::from_boolean (_tao_aggregate.backedUpStatus)) &&
(strm << _tao_aggregate.backUpObject) &&
(strm << _tao_aggregate.alarmInfoTrendIndication) &&
(strm << _tao_aggregate.alarmInfoThresholdInfo) &&
(strm << _tao_aggregate.stateChangeDefinition) &&
(strm << _tao_aggregate.monitoredAttributes) &&
(strm << _tao_aggregate.alarmInfoProposedRepairActions) &&
(strm << _tao_aggregate.additionalText.in ()) &&
(strm << _tao_aggregate.additionalInfo);
}
可以見到IDL的數據結構與流化是比較獨立分開的。CORBA的CDR編碼是通過IDL中規範定義的基本數據類型來判斷類型的流化。經過編譯的IDL定義的生成的C++結構是比較乾淨，基本不帶其他信息，或者成員，所以在編寫CORBA的程序的時候，我們不要再定義相同的C++數據結構，我們可以直接使用IDL編譯後的C++結構。