Newbie question: How to initialize this return param??

[klausa]

Hi,

I am trying (for the first time) to do a CORBA call in c++ (TAO, VC6
on win XP)

I have this IDL, notice, that exec has 3 parameters, the thirs is used
for a list of return values from the corba server.

module cna {
module mmsc {

struct BridgeParam {
string paramName;
string paramValue;
};

struct MMSCErrorDetails {
long errorCode;
string errorMessage;
};

exception MMSCException {
MMSCErrorDetails errorDetails;
};

typedef sequence< BridgeParam > BridgeParamList;

interface MMSCBridge {
void exec (in string requestName,
in BridgeParamList inParams,
out BridgeParamList outParams)
raises (MMSCException);

};
};
};

TAO compiles this to :

virtual void exec (
const char * requestName,
const ::cna::mmsc::CNAIdentification & cnaIdentification,
const ::cna::mmsc::BridgeParamList & inParams,
::cna::mmsc::BridgeParamList_out outParams
)

with
typedef
TAO_Seq_Out_T<
BridgeParamList,
BridgeParamList_var,
BridgeParam
>
BridgeParamList_out;

class BridgeParamList
: public
TAO_Unbounded_Sequence<
BridgeParam
>
{
struct BridgeParam
{
typedef BridgeParam_var _var_type;

static void _tao_any_destructor (void *);
TAO_String_Manager paramName;
TAO_String_Manager paramValue;
};

Now, when I want to call exec I must supply a variable for the third
parameter, that I wanted to name outPar. I tried like this:

::cna::mmsc::BridgeParam o1;
o1.paramName=CORBA::string_dup("USER_ID");
o1.paramValue=CORBA::string_dup("wna");
::cna::mmsc::BridgeParamList outList(2);
outList[0]=o1;
::cna::mmsc::BridgeParamList_var outList_var(&outList);

::cna::mmsc::BridgeParamList_out outPar(outList_var);

I that last line I get an exception! Somehow that is not the way its
done. Any tips, ideas of what I am doing wrong? Sorry, no, I cant
change the way exec is called, I have no controll over the source for
it. So the parameters have to stay the way there are, I cant just make
exec return a list as a return value.

TIA - klaus

[Stelios G. Sfakianakis]

klausa wrote:
> Hi,
>
> I am trying (for the first time) to do a CORBA call in c++ (TAO, VC6
> on win XP)
>
> I have this IDL, notice, that exec has 3 parameters, the thirs is used
> for a list of return values from the corba server.
>
>
> module cna {
> module mmsc {
>
> struct BridgeParam {
> string paramName;
> string paramValue;
> };
>
> struct MMSCErrorDetails {
> long errorCode;
> string errorMessage;
> };
>
> exception MMSCException {
> MMSCErrorDetails errorDetails;
> };
>
> typedef sequence< BridgeParam > BridgeParamList;
>
> interface MMSCBridge {
> void exec (in string requestName,
> in BridgeParamList inParams,
> out BridgeParamList outParams)
> raises (MMSCException);
>
> };
> };
> };

> [...]

> Now, when I want to call exec I must supply a variable for the third
> parameter, that I wanted to name outPar. I tried like this:
>
> ::cna::mmsc::BridgeParam o1;
> o1.paramName=CORBA::string_dup("USER_ID");
> o1.paramValue=CORBA::string_dup("wna");
> ::cna::mmsc::BridgeParamList outList(2);
> outList[0]=o1;
> ::cna::mmsc::BridgeParamList_var outList_var(&outList);
>
> ::cna::mmsc::BridgeParamList_out outPar(outList_var);
>
>
> I that last line I get an exception! Somehow that is not the way its
> done. Any tips, ideas of what I am doing wrong? Sorry, no, I cant
> change the way exec is called, I have no controll over the source for
> it. So the parameters have to stay the way there are, I cant just make
> exec return a list as a return value.

There is no need (in the client) to initialize an out parameter. You can
just pass the _var parameter like this:

::cna::mmsc::BridgeParamList_var outList_var;
bridge->exec("req", inParams, outList_var);

Check the Henning & Vinoski book
(http://cseng.aw.com/book/0,3828,0201379279,00.html) for details or its
sample chapter about the C++ mapping
(http://www.awl.com/cseng/titles/0-201-37927-9/cpp_mapping.pdf).

Cheers
Stelios

--
Stelios G. Sfakianakis | eHealth Laboratory
Voice: +30-2810-391650 | Institute of Computer Science
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