1. IDL to TTCN-3 mapping issues
due to practical experiences with e.g. Parlay IDLs
some gaps identified
major issue: missing modules scopes in TTCN-3
consider module declarations
introduce prefixes for interface definitions
discriminated unions:
additional aux. record of type needed
additional type definitions to express link bw. union and discr. types.
sequence: max. size mapping missing
name clashes due to added suffixes (“Type”, “Enum”, “Object”, “Interfaces”)

2. (1) consider module declarations
to consider module scope
to avoid name clashes
IDL
module identifier1 {
typedef long mylong1;
module identifier2 {
typedef string mystring2;
typedef mylong1 mylong2; }
TTCN
module identifier1 {type long mylong1;}
module identifier1__identifier2 {
import from identifier1 all;
type iso8859string mystring2;
type identifier1.mylong1 mylong2;

3. (2) interface related definitions
introduce prefixes to consider IDL scopes
to avoid name clashes
IDL
interface identifier {
attribute long attributeId ;
void operationname (in string param_value ) raises ( ExceptionType ) ;
//... other body definitions ... };
TTCN
group identifierInterface {
signature identifier__attributeIdGet () return long;
signature identifier__attributeIdSet (in long identifier__attributeId);
signature identifier__operationname (in iso8859string identifier__param_value) exception ( ExceptionType ) ;
//...other body definitions ... }

4. (3) discriminated unions: (a) additional aux. type needed
in case of sequences used in discr. unions
additional aux. record of type needed
union MyUnion switch( long ) {
case ‘0’ : boolean b;
case ‘1’ : char c;
case ‘2’ : octet o;
case ‘3’ : sequence<char> h;
case ‘4’ : short s; };
type union MyUnionType {
boolean b,
iso8859string c,
octetstring o,
MyUnion__3 h,
short s }
need to be introduced (generated):
type record of iso8859char MyUnion__3;

5. (3) discriminated unions: (b) link bw. union and discr. types
different IDL types map to same TTCN-3 definitions
additional types to keep the link information (needed at runtime by CORBA adapter implementation)
enum TpUIVariablePartType {P_UI_VARIABLE_PART_TIME, P_UI_VARIABLE_PART_DATE};
union TpUIVariableInfo switch(TpUIVariablePartType) {
case P_UI_VARIABLE_PART_TIME: TpTime VariablePartTime;
case P_UI_VARIABLE_PART_DATE: TpDate VariablePartDate;};
NEW in TTCN
type TpUIVariablePartType TpUIVariableInfo__Switch;
type enumerated TpUIVariableInfo__CasesType {case_P_UI_VARIABLE_PART_TIME, case_P_UI_VARIABLE_PART_DATE};

6. (4) mapping for IDL sequence
Extend the mapping for IDL sequence if a maximum size is specified:
We recommend a mapping to record of in TTCN-3 with limited number
of elements:
IDL Example:
typedef sequence <NameComponent, maximum_size> Name;
TTCN Example:
type record length (0, maximum_size - 1) of NameComponent Name;

7. (5) name clases due suffixes
aux. types are declared by adding suffixes: “Type”, “Enum”, “Object”, “Interfaces”
name clashes may occur if constructed types are already defined
e.g. introduce protected suffix: _
IDL
enum TpUIInfoType {P_UI_INFO_DATA,P_UI_INFO_ADDRESS};
union TpUIInfo switch(TpUIInfoType) {
case P_UI_INFO_DATA: TpString InfoData;
case P_UI_INFO_ADDRESS: TpURL InfoAddress;};
TTCN
type enumerated TpUIInfoType {P_UI_INFO_ID, P_UI_INFO_DATA, P_UI_INFO_ADDRESS}
type union TpUIInfoType_ [instead of standard rule: TpUIInfoType] {org__csapi.TpString InfoData, org__csapi.TpURL InfoAddress}
type enumerated TpUIInfoEnumType_ [instead of: TpUIInfoEnumType] {org__csapi_TpInt32_InfoID, org__csapi_TpString_InfoData, org__csapi_TpURL_InfoAddress}
type record TpUIInfo
{TpUIInfoEnumType__ETSI kind, TpUIInfoType__ETSI value_}