SIST ES 201 873-8 V4.8.1:2021

ETSI STANDARD
Methods for Testing and Specification (MTS);
The Testing and Test Control Notation version 3;
Part 8: The IDL to TTCN-3 Mapping

2 ETSI ES 201 873-8 V4.8.1 (2021-06)

Reference
RES/MTS-201873-8T3ed481
Keywords
IDL, testing, TTCN
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ETSI
3 ETSI ES 201 873-8 V4.8.1 (2021-06)
Contents
Intellectual Property Rights . 5
Foreword . 5
Modal verbs terminology . 5
1 Scope . 6
2 References . 6
2.1 Normative references . 6
2.2 Informative references . 6
3 Definition of terms, symbols and abbreviations . 7
3.1 Terms . 7
3.2 Symbols . 7
3.3 Abbreviations . 7
4 General considerations . 8
4.1 Introduction . 8
4.2 Approach . 9
4.3 Conformance and compatibility . 9
5 Lexical Conventions . 9
5.0 General . 9
5.1 Comments. 9
5.2 Identifiers . 9
5.3 Keywords . 9
5.4 Literals . 9
6 Pre-processing . 10
7 Importing from IDL specifications . 10
7.0 General . 10
7.1 Importing module declaration . 10
7.2 Importing interface declaration . 11
7.3 Importing value declaration . 12
7.4 Importing constant declaration . 12
8 Importing type declaration . 13
8.0 General . 13
8.1 IDL basic types . 13
8.1.0 General approach . 13
8.1.1 Integer and floating-point types . 13
8.1.2 Char and wide char type . 13
8.1.3 Boolean type . 14
8.1.4 Octet type . 14
8.1.5 Any type . 14
8.2 Constructed types . 14
8.2.0 General approach . 14
8.2.1 Struct . 14
8.2.2 Discriminated unions . 15
8.2.3 Enumerations . 16
8.3 Template types . 16
8.3.0 General approach . 16
8.3.1 Sequence . 16
8.3.2 String and wstring . 16
8.3.3 Fixed types . 17
8.4 Complex declarator . 17
8.4.0 General approach . 17
8.4.1 Arrays . 17
8.4.2 Native types . 17
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4 ETSI ES 201 873-8 V4.8.1 (2021-06)
9 Importing exception declaration . 17
10 Importing operation declaration . 19
11 Importing attribute declaration . 20
12 Names and scoping . 20
Annex A (informative): Examples . 22
A.1 The example . 22
A.2 IDL specification . 22
A.3 Derived TTCN-3 specification . 23
Annex B (informative): Mapping lists . 28
B.1 IDL keyword and concept mapping list . 28
B.2 Comparison of IDL, ASN.1, TTCN-2 and TTCN-3 data types . 29
Annex C (informative): Bibliography . 30
History . 31

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5 ETSI ES 201 873-8 V4.8.1 (2021-06)
Intellectual Property Rights
Essential patents
IPRs essential or potentially essential to normative deliverables may have been declared to ETSI. The declarations
pertaining to these essential IPRs, if any, are publicly available for ETSI members and non-members, and can be
found in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to
ETSI in respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the
ETSI Web server (https://ipr.etsi.org/).
Pursuant to the ETSI Directives including the ETSI IPR Policy, no investigation regarding the essentiality of IPRs,
including IPR searches, has been carried out by ETSI. No guarantee can be given as to the existence of other IPRs not
referenced in ETSI SR 000 314 (or the updates on the ETSI Web server) which are, or may be, or may become,
essential to the present document.
Trademarks
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ETSI claims no ownership of these except for any which are indicated as being the property of ETSI, and conveys no
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DECT™, PLUGTESTS™, UMTS™ and the ETSI logo are trademarks of ETSI registered for the benefit of its

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Foreword
This ETSI Standard (ES) has been produced by ETSI Technical Committee Methods for Testing and Specification
(MTS).
The present document is part 8 of a multi-part deliverable. Full details of the entire series can be found in part 1 [1].
Modal verbs terminology
In the present document "shall", "shall not", "should", "should not", "may", "need not", "will", "will not", "can" and
"cannot" are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of
provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.

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6 ETSI ES 201 873-8 V4.8.1 (2021-06)
1 Scope
The present document defines the mapping rules for CORBA IDL (as defined in clause 3 in [4]) to TTCN-3 (as defined
in ETSI ES 201 873-1 [1]) to enable testing of CORBA-based systems. The principles of mapping CORBA IDL to
TTCN-3 can be also used for the mapping of interface specification languages of other object-/component-based
technologies.
The specification of other mappings is outside the scope of the present document.
2 References
2.1 Normative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
https://docbox.etsi.org/Reference.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced documents are necessary for the application of the present document.
[1] ETSI ES 201 873-1: "Methods for Testing and Specification (MTS); The Testing and Test Control
Notation version 3; Part 1: TTCN-3 Core Language".
[2] Recommendation ITU-T T.50: "International Reference Alphabet (IRA) (Formerly International
Alphabet No. 5 or IA5) - Information technology - 7-bit coded character set for information
interchange".
[3] ISO/IEC 10646:2017: "Information technology -- Universal Coded Character Set (UCS)". ®
[4] CORBA 3.0: "The Common Object Request Broker: Architecture and Specification".
NOTE: Available at http://www.omg.org/spec/CORBA/.
2.2 Informative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] ETSI ES 201 873-7: "Methods for Testing and Specification (MTS); The Testing and Test Control
Notation version 3; Part 7: Using ASN.1 with TTCN-3".
[i.2] Void.
[i.3] Void.
[i.4] Void.
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7 ETSI ES 201 873-8 V4.8.1 (2021-06)
[i.5] ETSI ES 202 781: "Methods for Testing and Specification (MTS); The Testing and Test Control
Notation version 3; TTCN-3 Language Extensions: Configuration and Deployment Support".
[i.6] ETSI ES 202 782: "Methods for Testing and Specification (MTS); The Testing and Test Control
Notation version 3; TTCN-3 Language Extensions: TTCN-3 Performance and Real Time Testing".
[i.7] ETSI ES 202 784: "Methods for Testing and Specification (MTS); The Testing and Test Control
Notation version 3; TTCN-3 Language Extensions: Advanced Parameterization".
[i.8] ETSI ES 202 785: "Methods for Testing and Specification (MTS); The Testing and Test Control
Notation version 3; TTCN-3 Language Extensions: Behaviour Types".
[i.9] ETSI ES 202 786: "Methods for Testing and Specification (MTS); The Testing and Test Control
Notation version 3; TTCN-3 Language Extensions: Support of interfaces with continuous signals".
3 Definition of terms, symbols and abbreviations
3.1 Terms
Void.
3.2 Symbols
Void.
3.3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
ASN.1 Abstract Syntax Notation One
CCM CORBA Component Model ®
NOTE: By OMG .
CORBA Common Object Request Broker Architecture ®
NOTE: By OMG .
DCE Distributed Computing Environment
NOTE: By OSF.
TM
EJB Enterprise JavaBeans ®
NOTE: By Sun .
IDL Interface Definition Language
NET XML-based component technology ®
NOTE: By Microsoft .
OMG Object Management Group
OSF Open Software Foundation
SUT System Under Test
TTCN Testing and Test Control Notation
XML eXtended Markup Language
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8 ETSI ES 201 873-8 V4.8.1 (2021-06)
4 General considerations
4.1 Introduction
Object-based technologies (such as CORBA, DCOM, DCE) and component-based technologies (such as CCM, EJB, ®
Microsoft , NET) use interface specifications to describe the structure of an object-/component-based system and its
operations and capabilities to interact with the environment. These interface specifications support interoperability and
reusability of objects/components.
The techniques used for interface specifications are often called Interface Definition Language (IDL), for example ®
CORBA IDL, Microsoft IDL or DCE IDL. These languages are comparable in their abilities to define system
interfaces, operations at system interfaces and system structures to various extends. They differ in details of the
object/component model.
When considering the testing of object-/component-based systems with TTCN-3, one is faced with the problem of
accessing the systems to be tested via the system interfaces as described in an IDL specification. In particular, for
TTCN-3 based test systems a direct import of IDL specifications into the test specifications for the use of e.g. system's
interface, operation and exception definitions is prevalent to any manual transformation into TTCN-3.
The present document discusses the mapping of CORBA IDL specifications into TTCN-3. This mapping rules out the
principles not only for CORBA IDL, but also for other interface specification languages. The mapping can be adapted
to the details of other interface specification languages.
The Interface Definition Language (IDL) (clause 3 in [4]) is a base of the whole Common Object Request Broker
Architecture (CORBA) [4] and an important point in developing distributed systems with CORBA. It allows the reuse
and interoperability of objects in a system. A mapping between IDL and a programming language is defined in the
CORBA standard. IDL is very similar to C++ containing pre-processor directives (include, comments, etc.), grammar as
well as constant, type and operation declarations. There are no programming language features like, e.g. if-
statements.
The core language of TTCN-3 is defined in ETSI ES 201 873-1 [1] and provides a full text-based syntax, static
semantics and operational semantics. The IDL mapping provides a definition for the use of the core language with IDL
(figure 1).
Configuration Advanced OO
Advanced Behavior Performance Continuous TTCN-3
…
and deploy- Matching Features
Parameteri- Types and Real signals Packages
ment support
zation Time Testing
ASN.1 types
and values
IDL types
TTCN-3
XML types
Core
TTCN-3 User
Language
JSON types
& values
The shaded boxes are not
defined in the present
Other types &
document
values
Figure 1: User's view of the core language and its packages
It makes no difference for the mapping if requested or provided interfaces are required by the test system and SUT.
Hence, TTCN can be used on client and server side without modifications to the mapping rules.
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9 ETSI ES 201 873-8 V4.8.1 (2021-06)
The present document is structured similar to the IDL specification document to provide easy access to the mapping of
each IDL element.
4.2 Approach
Two different approaches can be identified: the use of either implicit or explicit mapping. The implicit mapping makes
use of the import mechanism of TTCN-3, denoted by the keywords language and import. It facilitates the immediate use
of data specified in other languages. Therefore, the definition of a specific data interface for each of these languages is
required. Currently, ASN.1 data can be used besides the native TTCN-3 types (see ETSI ES 201 873-7 [i.1]).
The present document follows the approach of explicit mapping, i.e. IDL data are translated into appropriate TTCN-3
data. And only those TTCN-3 data are further used in the test specification.
4.3 Conformance and compatibility
For an implementation claiming to support the IDL to TTCN-3 mapping, all features specified in the present document
shall be implemented consistently with the requirements given in the present document and in ETSI ES 201 873-1 [1].
5 Lexical Conventions
5.0 General
The lexical conventions of IDL define the comments, identifiers, keywords and literals conventions which are described
in the following clauses.
5.1 Comments
Comment definitions in TTCN-3 and IDL are the same and therefore, no conversion of comments is necessary.
5.2 Identifiers
IDL identifier rules define a subset of the TTCN-3 rules in which no conversion is necessary.
5.3 Keywords
When IDL is used with TTCN-3 the keywords of TTCN-3 shall not be used as identifiers in an IDL module.
5.4 Literals
The definition of literals differs slightly between IDL and TTCN-3 why some modifications have to be made. Table B.1
gives the mapping for each literal type.
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10 ETSI ES 201 873-8 V4.8.1 (2021-06)
Table 1: Literal mapping
Literal IDL TTCN
Integer no "0" as first digit no "0" as first digit
Octet "0" as first digit 'FF96'O
Hex "0X" or "0x" as first digits 'AB01D'H
Floating 1222.44E5 (Base 10) 1222.44E5 (Base 10)
Char 'A' "A"
Wide char L"A" "A"
Boolean TRUE, FALSE true, false
String "text" "text"
Wide string L"text" "text"
Fixed point 33.33D (see useful type IDLfixed)

IDL uses the ISO Latin-1 character set for string and wide string literals and TTCN-3 uses Recommendation
ITU-T T.50 [2] for string literals and ISO/IEC 10646 [3] for wide string literals.
6 Pre-processing
Pre-processor statements are not matched to TTCN-3 because the IDL specification shall be used after pre-processing it.
7 Importing from IDL specifications
7.0 General
The import of module, interface, value and constant declaration are described in this clause. The type and exception
declaration as well as the bodies of interfaces are described later.
All imported IDL declarations are in TTCN-3 public by default (see clause 8.2.5 of ETSI ES 201 873-1 [1]).
7.1 Importing module declaration
IDL modules are mapped to TTCN-3 modules. Nested IDL modules shall be flattened accordingly to TTCN-3 modules.
As one IDL module can contain many nested IDL modules where several nested modules can have equal names in
different scopes, these names can clash. Hence, module names identifiers are to be used which are composed of the
identifiers of the upper level IDL modules (from hierarchical point of view) and the nested IDL module name, separated
one from each other by two underscores.
According to the IDL scoping rules nested modules have access to the scope of upper level modules. As there are no
nested modules in TTCN-3, TTCN-3 modules have to import upper level modules. For avoiding name clashes, a prefix
for the imported definitions composed of the identifier of the module from which it is imported shall be used. The prefix
and the identifier are separated by a dot (.) as defined in TTCN-3.
IDL EXAMPLE:
module identifier1 {
typedef long mylong1;
module identifier2 {
typedef string mystring2;
typedef mylong1 mylong2;
module identifier3 {
typedef mylong1 long_from_module_1;
typedef mystring2 string_from_module_2;
typedef mylong2 long_from_module_1_2;
};
};
};
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11 ETSI ES 201 873-8 V4.8.1 (2021-06)

TTCN EXAMPLE:
module identifier1 {
type long mylong1;
}
module identifier1__identifier2 {
import from identifier1 all;
type iso8859string mystring2;
type identifier1.mylong1 mylong2;
}
module identifier1__identifier2__identifier3 {
import from identifier1 all;
import from identifier1__identifier2 all;

type identifier1.mylong1 long_from_module_1;
type identifier1__identifier2.mystring2 string_from_module_2;
type identifier1__identifier2.mylong2 long_from_module_1_2;
};
7.2 Importing interface declaration
Interfaces are flattened and all interface definitions are stored in one group. In contrast to interfaces in IDL, groups in
TTCN-3 do not create a scope. Therefore, prefixes for all identifiers of type definitions inside of the interface shall be
used, which are a combination of the interface name and two underscores as the prefix.
Import of single interface definitions from other modules via the importing group statement is possible. This can be
used if inheritance is used in the IDL specification.
For each interface, a procedure-based port type is defined for the test specification. It is associated with signatures
translated from attributes and operations of the interface.
An IDL attribute is mapped to two signatures: one for the setting of a value and one for getting it. These signatures have
names composed of the prefix (interface name and two underscores), attribute name and the word "Set" (except for
"readonly") or "Get" correspondingly.
Since an interface can be used in operation parameters to pass object references, an address type is also declared in the
data part - the concrete implementation is left to the user. Components are used as collection of interfaces or objects.
IDL EXAMPLE:
interface identifier {
attribute long attributeId ;
void operationname ( in string param_value ) raises ( ExceptionType ) ;
... other body definitions ...
};
TTCN EXAMPLE:
group identifierInterface {
signature identifier__attributeIdGet () return long
exception ( . /* and all system exceptions defined in clause 9 */ );
signature identifier__attributeIdSet (in long identifier__attributeId)
exception ( . /* and all system exceptions defined in clause 9 */ );

signature identifier__operationname ( in iso8859string identifier__param_value )
exception ( ExceptionType, . /* and all system exceptions defined in clause 9 */ ) ;

...other body definitions ...
type port identifier procedure { . }
type charstring identifierObject; /* a possible definition for the address type */
type identifierObject address;
}
Interface inheritance is executed by rolling out all inherited elements. Thus, they have to be handled as defined in the
interface itself. Multiple inheritance elements have to be inherited only once! As normally an inherited IDL interface
uses types defined in the module, usually it is essential to import the complete mapped TTCN-3 module. All inherited
elements have to be rolled out directly in the TTCN-3 group for the interface, even if the inheritance is multiple.
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12 ETSI ES 201 873-8 V4.8.1 (2021-06)
Forward references of interfaces are provided by forward referencing the according port of the interface. Local
interfaces are treated as normal interfaces. However it is recommend not to use forward references and to move a
TTCN-3 definition of the interface (group) to a place where a forward definition is used first time.
7.3 Importing value declaration
In contrast to type interface, the IDL type value has local operations that are not used outside the object, and are
therefore not relevant from the functional testing point of view. However, since the public attributes of value instances
are used to communicate object states, the IDL value type is mapped to the record type in TTCN-3.
The example below shows how to map valuetype and was used from clause 5.2.5 in [4].
IDL EXAMPLE:
valuetype EmployeeRecord {
// note this is not a CORBA::Object
// state definition
private string name;
private string email;
private string SSN;
// initializer
factory init(
in string name, in string SSN );
};
TTCN EXAMPLE:
type record EmployeeRecord {
iso8859string name,
iso8859string email,
iso8859string SSN
}
7.4 Importing constant declaration
Constant declarations can be transformed by use of literal (see table B.1) and operator mapping for floating-point and
integer values (see table 2).
Table 2: Operators for constant expressions
Operator IDL TTCN
Unary floating-point
Positive + +
Negative - -
Binary floating-point
Addition + +
Subtraction - -
Multiplication * *
Division / /
Unary integer
Positive + +
Negative - -
Bit-complement ~ not4b
Binary integer
Addition + +
Subtraction - -
Multiplication * *
Division / /
Modulo % mod
Shift left << <<
Shift right >> >>
Bitwise and & and4b
Bitwise or | or4b
Bitwise xor ^ xor4b
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13 ETSI ES 201 873-8 V4.8.1 (2021-06)
IDL EXAMPLE:
const long number = 017; // 017 == 0xF == 15
const long size = ( ( number << 3 ) % 0x1F ) & 0123;

TTCN EXAMPLE:
const long number := "17"O;
const long size := ( ( number << 3 ) mod '1F'H ) and4b '0123'O;

8 Importing type declaration
8.0 General
Type declaration mapping will be shown in the following clauses.
A construct for naming data types and defining new types by using the keyword typedef is provided by IDL. This can
be done under TTCN-3 via the keyword type, too.
To enhance readability and to provide a clear distinction, mapped IDL data types get the prefix IDL and the extension
attribute "variant" as done in TTCN-3 for type IDLfixed (see clause E.2.3.0 in ETSI ES 201 873-1 [1]).
8.1 IDL basic types
8.1.0 General approach
IDL basic data types are mapped to predefined or useful types in TTCN-3.
8.1.1 Integer and floating-point types
Integer and floating-point types are mapped onto the corresponding useful types short, unsignedshort, long,
unsignedlong, longlong, unsignedlonglong, IEEE754float, IEEE754double, and IEEE754extdouble.
IDL EXAMPLE:
const long  size    = ( ( number << 3 ) % 0x1F ) & 0123;
const float  decimal  = 15.7;

TTCN EXAMPLE:
const long      size   := ( ( number << 3 ) mod '1F'H ) and4b '0123'O;
const IEEE754float  decimal := 15.7;

8.1.2 Char and wide char type
The IDL char and wide char type represent a single and wide character. They are mapped to the self defined type
iso8859char and type uchar.
IDL EXAMPLE:
const char letter   = 'ABCD';
const wchar wideLetter = L'ABCD';

TTCN EXAMPLE:
type universal charstring uchar length(1);
type uchar iso8859char (char ( 0,0,0,0 ) . char ( 0,0,0,255)) with { variant "8 bit" };

const iso8859char letter := char ( 65, 66, 67, 68 );
const uchar wideLetter := char ( 65, 66, 67, 68 );

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8.1.3 Boolean type
The IDL boolean type is equivalent to the TTCN-3 boolean type.
IDL EXAMPLE:
const boolean isValid = TRUE;
TTCN EXAMPLE:
const boolean isValid = true;
8.1.4 Octet type
Octet cannot be mapped onto an integer type because it has the special feature that it will not change its internal
ordering if transferred between different system architectures. To represent it octet is mapped to octetstring.
IDL EXAMPLE:
const octet data = 0x55;
TTCN EXAMPLE:
const octetstring data = '55'H

8.1.5 Any type
The IDL any type is mapped onto anytype in TTCN-3 which was especially introduced for this mapping.
IDL EXAMPLE:
typedef any AllTypes;
TTCN EXAMPLE:
type anytype AllTypes;
8.2 Constructed types
8.2.0 General approach
IDL provides the three constructed types struct, union, and enum. Recursive construction of types is only permitted
with the sequence template.
8.2.1 Struct
struct is used to collect ordered data in one place where it is mapped onto record in TTCN-3.
IDL EXAMPLE:
typedef struct NC {
string id;
string kind;
} NameComponent;
TTCN EXAMPLE:
type record NameComponent {
iso8859string id,
iso8859string kind
}
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15 ETSI ES 201 873-8 V4.8.1 (2021-06)
8.2.2 Discriminated unions
In IDL, unions are discriminated to determine the actual type. Therefore, a record type is used, which contains two
members. The first one stores the discriminator information using an enumeration type. The second member is a
TTCN-3 union type which members are defined according to the specified IDL union members.
In addition, two types are defined to express the link between discriminator's type and union's type: a type to reflect the
discriminating type of a union and an enumeration to distinguish the discriminated cases. Using the information
provided by these type definitions, the marshalling/unmarshalling for discriminated unions is possible in an
unambiguous manner: to encode or decode a union value, the value of the kind field to resolve the corresponding
chosen option and calculate then the real value for the discriminator by resolving this value in the discriminator
enumeration shall be used.
IDL EXAMPLE 1:
union MyUnion switch( long ) {
case 0 : boolean b;
case 1 : char c;
case 2 : octet o;
case 3 : short s; };
TTCN EXAMPLE 1:
type long MyUnion__Switch;
type union MyUnionType {
boolean b,
iso8859string c,
octetstring o,
short s }
type enumerated MyUnionEnumType {
boolean_b, iso8859string_c, octetstring_o, short_s
}
type record MyUnion {
MyUnionEnumType kind,
MyUnionType value
}
IDL EXAMPLE 2:
Enum MyDiscr {
BOOLEAN_DISCR,
CHAR_DISCR,
OCTET_DISCR,
SEQ_DISCR,
SHORT_DISCR
};
union MyUnion switch( MyDiscr ) {
case BOOLEAN_DISCR : boolean b;
case SHORT_DISCR : short s;
};
TTCN EXAMPLE 2:
type enumerated MyDiscr {
BOOLEAN_DISCR, CHAR_DISCR, OCTET_DISCR, SEQ_DISCR, SHORT_DISCR
}
type MyDiscr MyUnion__Switch;
type enumerated MyUnion__CasesType {
case_BOOLEAN_DISCR,
case_SHORT_DISCR
}
type union MyUnionType {
boolean b,
short s
}
type enumerated MyUnionEnumType {
ETSI
16 ETSI ES 201 873-8 V4.8.1 (2021-06)
boolean_b,
short_s
}
type record MyUnion {
MyUnionEnumType kind_,
MyUnionType value_
}
8.2.3 Enumerations
Enumerations are equally defined in IDL and TTCN-3.
IDL EXAMPLE:
enum NotFoundReason {
missing_node,
not_context,
not_object };
TTCN EXAMPLE:
type enumerated NotFoundReason {
missing_node,
not_context,
not_object }
8.3 Template types
8.3.0 General approach
IDL supports the template types sequence, string, wide string and fixed type.
8.3.1 Sequence
IDL sequence is mapped to record of in TTCN-3 to maintain order and to allow unbounded sequences.
IDL EXAMPLE 1:
typedef sequence Name;

TTCN EXAMPLE 1:
type record of NameComponent Name;

IDL sequences with a specified maximum size are mapped to record of with limited number of elements to maintain
order and restrict the maximum number of elements.
IDL EXAMPLE 2:
typedef sequence Name;

TTCN EXAMPLE 2:
type record length (0, maximum_size-1) of NameComponent Name;

8.3.2 String and wstring
string and wstring types are sequences of char and wchar. Therefore, string and wstring are mapped to the useful
type iso8859string and universal charstring.
IDL EXAMPLE:
const string name =    "My String";
const wstring wideName = L"My String";

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17 ETSI ES 201 873-8 V4.8.1 (2021-06)
TTCN EXAMPLE:
const iso8859string name := "My String";
const universal charstring wideName := "My String";

8.3.3 Fixed types
The fixed type represents a fixed-point decimal number. It is mapped to the corresponding useful type IDLfixed in
TTCN-3 (see clause E.2.3.0 in ETSI ES 201 873-1 [1]).
IDL EXAMPLE:
typedef fixed<12,7> myFix;
TTCN EXAMPLE:
template IDLfixed myFixTemplate := { 12, 7, ? }; // e.g. in module definition part
var IDLfixed myFix := { 12, 7, "12345.1234567" }; // e.g. in module control part

8.4 Complex declarator
8.4.0 General approach
The last kind of type declarators are the complex array and native types.
8.4.1 Arrays
IDL array is equal to the TTCN-3 array type.
IDL EXAMPLE:
typedef long NumberList[100];
TTCN EXAMPLE:
type long NumberList[100];
8.4.2 Native types
Native types are used to allow implementation of dependent types. TTCN-3 provides the type address to address
entities inside a SUT. Hence, address can be used for mapping of type native and concrete implementation is left to the
user.
IDL EXAMPLE:
typedef native MyNativeVariable;

TTCN EXAMPLE:
type MyNativeVariable address;

9 Importing exception declaration
In IDL, exceptions are used in conjunction with operations to handle exceptional conditions during an operation call.
Thus, a special struct-like exception type is provided which has to be associated with each operation that can trigger
this exception. TTCN-3 also supports the use of exceptions with procedure calls by binding it to signature definitions.
However, it provides no special exception type. Hence, exceptions are defined by using type record.
A definition of an exception is shown in the following example. The use of exception binding in signature definitions
and exception catching is shown in the context of operation declaration.
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18 ETSI ES 201 873-8 V4.8.1 (2021-06)
IDL EXAMPLE:
exception NotFoundException {
NotFoundReason why;
Name rest_of_name; };
TTCN EXAMPLE:
// definition of an exception type
type record NotFoundException {
NotFoundReason why,
Name rest_of_name }
// definition of a template for the
// defined exception type
template NotFoundException
NotFoundExceptionTemplate ( NotFoundReason reason, Name name ) := {
why := reason,
rest_of_name := name }
In addition to user defined exceptions, there are CORBA system exceptions defined in chapter 4 in [4]. In order to
make them available for use in TTCN-3, the following definitions are to be used:
// CORBA system exceptions
type record UNKNOWN{}  // the unknown type record
type record BAD_PARAM{}  // an invalid parameter was passed
type record NO_MEMORY{}  // dynamic memory allocation failure
type record IMP_LIMIT{}  // violated implementation limit
type record COMM_FAILURE{}  // communication failure
type record INV_OBJREF{}  // invalid object reference
type record NO_PERMISSION{} // no permission for attempted op.
type record INTERNAL{}  // ORB internal error
type record MARSHAL{}  // error marshaling param/result
type record INITIALIZE{}  // ORB initialization failure
type record NO_IMPLEMENT{}  // operation implementation unavailable
type record BAD_TYPECODE{}  // bad typecode
type record BAD_OPERATION{} // invalid operation
type record NO_RESOURCES{}  // insufficient resources for req.
type record NO_RESPONSE{}  // response to req. not yet available
type record PERSIST_STORE{} // persistent storage failure
type record BAD_INV_ORDER{} // routine invocations out of order
type record TRANSIENT{}  // transient failure - reissue request
type record FREE_MEM{}  // cannot free memory
type record INV_IDENT{}  // invalid identifier syntax
type record INV_FLAG{}  // invalid flag was specified
type record INTF_REPOS{}  // error accessing interface repository
type record BAD_CONTEXT{}  // error processing context object
type record OBJ_ADAPTER{}  // failure detected by object adapter
type record DATA_CONVERSION{} // data conversion error
type record OBJECT_NOT_EXIST{} // non-existent object, delete reference
type record TRANSACTION_REQUIRED{} // transaction required
type record TRANSACTION_ROLLEDBACK{}// transaction rolled back
type record INVALID_TRANSACTION{} // invalid transaction
type record INV_POLICY{}  // invalid policy
type record CODESET_INCOMPATIBLE{} // incompatible code set
type record REBIND{}  // rebind needed
type record TIM
...

SLOVENSKI STANDARD
01-september-2021
Metode za preskušanje in specificiranje (MTS) - 3. različica zapisa preskušanja in
krmiljenja preskusov - 8. del: Preslikava IDL v TTCN-3
Methods for Testing and Specification (MTS) - The Testing and Test Control Notation
version 3 - Part 8: The IDL to TTCN-3 Mapping
Ta slovenski standard je istoveten z: ETSI ES 201 873-8 V4.8.1 (2021-06)
ICS:
33.040.01 Telekomunikacijski sistemi na Telecommunication systems
splošno in general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

ETSI STANDARD
Methods for Testing and Specification (MTS);
The Testing and Test Control Notation version 3;
Part 8: The IDL to TTCN-3 Mapping

2 ETSI ES 201 873-8 V4.8.1 (2021-06)

Reference
RES/MTS-201873-8T3ed481
Keywords
IDL, testing, TTCN
ETSI
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ETSI
3 ETSI ES 201 873-8 V4.8.1 (2021-06)
Contents
Intellectual Property Rights . 5
Foreword . 5
Modal verbs terminology . 5
1 Scope . 6
2 References . 6
2.1 Normative references . 6
2.2 Informative references . 6
3 Definition of terms, symbols and abbreviations . 7
3.1 Terms . 7
3.2 Symbols . 7
3.3 Abbreviations . 7
4 General considerations . 8
4.1 Introduction . 8
4.2 Approach . 9
4.3 Conformance and compatibility . 9
5 Lexical Conventions . 9
5.0 General . 9
5.1 Comments. 9
5.2 Identifiers . 9
5.3 Keywords . 9
5.4 Literals . 9
6 Pre-processing . 10
7 Importing from IDL specifications . 10
7.0 General . 10
7.1 Importing module declaration . 10
7.2 Importing interface declaration . 11
7.3 Importing value declaration . 12
7.4 Importing constant declaration . 12
8 Importing type declaration . 13
8.0 General . 13
8.1 IDL basic types . 13
8.1.0 General approach . 13
8.1.1 Integer and floating-point types . 13
8.1.2 Char and wide char type . 13
8.1.3 Boolean type . 14
8.1.4 Octet type . 14
8.1.5 Any type . 14
8.2 Constructed types . 14
8.2.0 General approach . 14
8.2.1 Struct . 14
8.2.2 Discriminated unions . 15
8.2.3 Enumerations . 16
8.3 Template types . 16
8.3.0 General approach . 16
8.3.1 Sequence . 16
8.3.2 String and wstring . 16
8.3.3 Fixed types . 17
8.4 Complex declarator . 17
8.4.0 General approach . 17
8.4.1 Arrays . 17
8.4.2 Native types . 17
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4 ETSI ES 201 873-8 V4.8.1 (2021-06)
9 Importing exception declaration . 17
10 Importing operation declaration . 19
11 Importing attribute declaration . 20
12 Names and scoping . 20
Annex A (informative): Examples . 22
A.1 The example . 22
A.2 IDL specification . 22
A.3 Derived TTCN-3 specification . 23
Annex B (informative): Mapping lists . 28
B.1 IDL keyword and concept mapping list . 28
B.2 Comparison of IDL, ASN.1, TTCN-2 and TTCN-3 data types . 29
Annex C (informative): Bibliography . 30
History . 31

ETSI
5 ETSI ES 201 873-8 V4.8.1 (2021-06)
Intellectual Property Rights
Essential patents
IPRs essential or potentially essential to normative deliverables may have been declared to ETSI. The declarations
pertaining to these essential IPRs, if any, are publicly available for ETSI members and non-members, and can be
found in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to
ETSI in respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the
ETSI Web server (https://ipr.etsi.org/).
Pursuant to the ETSI Directives including the ETSI IPR Policy, no investigation regarding the essentiality of IPRs,
including IPR searches, has been carried out by ETSI. No guarantee can be given as to the existence of other IPRs not
referenced in ETSI SR 000 314 (or the updates on the ETSI Web server) which are, or may be, or may become,
essential to the present document.
Trademarks
The present document may include trademarks and/or tradenames which are asserted and/or registered by their owners.
ETSI claims no ownership of these except for any which are indicated as being the property of ETSI, and conveys no
right to use or reproduce any trademark and/or tradename. Mention of those trademarks in the present document does
not constitute an endorsement by ETSI of products, services or organizations associated with those trademarks.
DECT™, PLUGTESTS™, UMTS™ and the ETSI logo are trademarks of ETSI registered for the benefit of its

Members. 3GPP™ and LTE™ are trademarks of ETSI registered for the benefit of its Members and of the 3GPP
Organizational Partners. oneM2M™ logo is a trademark of ETSI registered for the benefit of its Members and of the ®
oneM2M Partners. GSM and the GSM logo are trademarks registered and owned by the GSM Association.
Foreword
This ETSI Standard (ES) has been produced by ETSI Technical Committee Methods for Testing and Specification
(MTS).
The present document is part 8 of a multi-part deliverable. Full details of the entire series can be found in part 1 [1].
Modal verbs terminology
In the present document "shall", "shall not", "should", "should not", "may", "need not", "will", "will not", "can" and
"cannot" are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of
provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.

ETSI
6 ETSI ES 201 873-8 V4.8.1 (2021-06)
1 Scope
The present document defines the mapping rules for CORBA IDL (as defined in clause 3 in [4]) to TTCN-3 (as defined
in ETSI ES 201 873-1 [1]) to enable testing of CORBA-based systems. The principles of mapping CORBA IDL to
TTCN-3 can be also used for the mapping of interface specification languages of other object-/component-based
technologies.
The specification of other mappings is outside the scope of the present document.
2 References
2.1 Normative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
https://docbox.etsi.org/Reference.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced documents are necessary for the application of the present document.
[1] ETSI ES 201 873-1: "Methods for Testing and Specification (MTS); The Testing and Test Control
Notation version 3; Part 1: TTCN-3 Core Language".
[2] Recommendation ITU-T T.50: "International Reference Alphabet (IRA) (Formerly International
Alphabet No. 5 or IA5) - Information technology - 7-bit coded character set for information
interchange".
[3] ISO/IEC 10646:2017: "Information technology -- Universal Coded Character Set (UCS)". ®
[4] CORBA 3.0: "The Common Object Request Broker: Architecture and Specification".
NOTE: Available at http://www.omg.org/spec/CORBA/.
2.2 Informative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] ETSI ES 201 873-7: "Methods for Testing and Specification (MTS); The Testing and Test Control
Notation version 3; Part 7: Using ASN.1 with TTCN-3".
[i.2] Void.
[i.3] Void.
[i.4] Void.
ETSI
7 ETSI ES 201 873-8 V4.8.1 (2021-06)
[i.5] ETSI ES 202 781: "Methods for Testing and Specification (MTS); The Testing and Test Control
Notation version 3; TTCN-3 Language Extensions: Configuration and Deployment Support".
[i.6] ETSI ES 202 782: "Methods for Testing and Specification (MTS); The Testing and Test Control
Notation version 3; TTCN-3 Language Extensions: TTCN-3 Performance and Real Time Testing".
[i.7] ETSI ES 202 784: "Methods for Testing and Specification (MTS); The Testing and Test Control
Notation version 3; TTCN-3 Language Extensions: Advanced Parameterization".
[i.8] ETSI ES 202 785: "Methods for Testing and Specification (MTS); The Testing and Test Control
Notation version 3; TTCN-3 Language Extensions: Behaviour Types".
[i.9] ETSI ES 202 786: "Methods for Testing and Specification (MTS); The Testing and Test Control
Notation version 3; TTCN-3 Language Extensions: Support of interfaces with continuous signals".
3 Definition of terms, symbols and abbreviations
3.1 Terms
Void.
3.2 Symbols
Void.
3.3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
ASN.1 Abstract Syntax Notation One
CCM CORBA Component Model ®
NOTE: By OMG .
CORBA Common Object Request Broker Architecture ®
NOTE: By OMG .
DCE Distributed Computing Environment
NOTE: By OSF.
TM
EJB Enterprise JavaBeans ®
NOTE: By Sun .
IDL Interface Definition Language
NET XML-based component technology ®
NOTE: By Microsoft .
OMG Object Management Group
OSF Open Software Foundation
SUT System Under Test
TTCN Testing and Test Control Notation
XML eXtended Markup Language
ETSI
8 ETSI ES 201 873-8 V4.8.1 (2021-06)
4 General considerations
4.1 Introduction
Object-based technologies (such as CORBA, DCOM, DCE) and component-based technologies (such as CCM, EJB, ®
Microsoft , NET) use interface specifications to describe the structure of an object-/component-based system and its
operations and capabilities to interact with the environment. These interface specifications support interoperability and
reusability of objects/components.
The techniques used for interface specifications are often called Interface Definition Language (IDL), for example ®
CORBA IDL, Microsoft IDL or DCE IDL. These languages are comparable in their abilities to define system
interfaces, operations at system interfaces and system structures to various extends. They differ in details of the
object/component model.
When considering the testing of object-/component-based systems with TTCN-3, one is faced with the problem of
accessing the systems to be tested via the system interfaces as described in an IDL specification. In particular, for
TTCN-3 based test systems a direct import of IDL specifications into the test specifications for the use of e.g. system's
interface, operation and exception definitions is prevalent to any manual transformation into TTCN-3.
The present document discusses the mapping of CORBA IDL specifications into TTCN-3. This mapping rules out the
principles not only for CORBA IDL, but also for other interface specification languages. The mapping can be adapted
to the details of other interface specification languages.
The Interface Definition Language (IDL) (clause 3 in [4]) is a base of the whole Common Object Request Broker
Architecture (CORBA) [4] and an important point in developing distributed systems with CORBA. It allows the reuse
and interoperability of objects in a system. A mapping between IDL and a programming language is defined in the
CORBA standard. IDL is very similar to C++ containing pre-processor directives (include, comments, etc.), grammar as
well as constant, type and operation declarations. There are no programming language features like, e.g. if-
statements.
The core language of TTCN-3 is defined in ETSI ES 201 873-1 [1] and provides a full text-based syntax, static
semantics and operational semantics. The IDL mapping provides a definition for the use of the core language with IDL
(figure 1).
Configuration Advanced OO
Advanced Behavior Performance Continuous TTCN-3
…
and deploy- Matching Features
Parameteri- Types and Real signals Packages
ment support
zation Time Testing
ASN.1 types
and values
IDL types
TTCN-3
XML types
Core
TTCN-3 User
Language
JSON types
& values
The shaded boxes are not
defined in the present
Other types &
document
values
Figure 1: User's view of the core language and its packages
It makes no difference for the mapping if requested or provided interfaces are required by the test system and SUT.
Hence, TTCN can be used on client and server side without modifications to the mapping rules.
ETSI
9 ETSI ES 201 873-8 V4.8.1 (2021-06)
The present document is structured similar to the IDL specification document to provide easy access to the mapping of
each IDL element.
4.2 Approach
Two different approaches can be identified: the use of either implicit or explicit mapping. The implicit mapping makes
use of the import mechanism of TTCN-3, denoted by the keywords language and import. It facilitates the immediate use
of data specified in other languages. Therefore, the definition of a specific data interface for each of these languages is
required. Currently, ASN.1 data can be used besides the native TTCN-3 types (see ETSI ES 201 873-7 [i.1]).
The present document follows the approach of explicit mapping, i.e. IDL data are translated into appropriate TTCN-3
data. And only those TTCN-3 data are further used in the test specification.
4.3 Conformance and compatibility
For an implementation claiming to support the IDL to TTCN-3 mapping, all features specified in the present document
shall be implemented consistently with the requirements given in the present document and in ETSI ES 201 873-1 [1].
5 Lexical Conventions
5.0 General
The lexical conventions of IDL define the comments, identifiers, keywords and literals conventions which are described
in the following clauses.
5.1 Comments
Comment definitions in TTCN-3 and IDL are the same and therefore, no conversion of comments is necessary.
5.2 Identifiers
IDL identifier rules define a subset of the TTCN-3 rules in which no conversion is necessary.
5.3 Keywords
When IDL is used with TTCN-3 the keywords of TTCN-3 shall not be used as identifiers in an IDL module.
5.4 Literals
The definition of literals differs slightly between IDL and TTCN-3 why some modifications have to be made. Table B.1
gives the mapping for each literal type.
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10 ETSI ES 201 873-8 V4.8.1 (2021-06)
Table 1: Literal mapping
Literal IDL TTCN
Integer no "0" as first digit no "0" as first digit
Octet "0" as first digit 'FF96'O
Hex "0X" or "0x" as first digits 'AB01D'H
Floating 1222.44E5 (Base 10) 1222.44E5 (Base 10)
Char 'A' "A"
Wide char L"A" "A"
Boolean TRUE, FALSE true, false
String "text" "text"
Wide string L"text" "text"
Fixed point 33.33D (see useful type IDLfixed)

IDL uses the ISO Latin-1 character set for string and wide string literals and TTCN-3 uses Recommendation
ITU-T T.50 [2] for string literals and ISO/IEC 10646 [3] for wide string literals.
6 Pre-processing
Pre-processor statements are not matched to TTCN-3 because the IDL specification shall be used after pre-processing it.
7 Importing from IDL specifications
7.0 General
The import of module, interface, value and constant declaration are described in this clause. The type and exception
declaration as well as the bodies of interfaces are described later.
All imported IDL declarations are in TTCN-3 public by default (see clause 8.2.5 of ETSI ES 201 873-1 [1]).
7.1 Importing module declaration
IDL modules are mapped to TTCN-3 modules. Nested IDL modules shall be flattened accordingly to TTCN-3 modules.
As one IDL module can contain many nested IDL modules where several nested modules can have equal names in
different scopes, these names can clash. Hence, module names identifiers are to be used which are composed of the
identifiers of the upper level IDL modules (from hierarchical point of view) and the nested IDL module name, separated
one from each other by two underscores.
According to the IDL scoping rules nested modules have access to the scope of upper level modules. As there are no
nested modules in TTCN-3, TTCN-3 modules have to import upper level modules. For avoiding name clashes, a prefix
for the imported definitions composed of the identifier of the module from which it is imported shall be used. The prefix
and the identifier are separated by a dot (.) as defined in TTCN-3.
IDL EXAMPLE:
module identifier1 {
typedef long mylong1;
module identifier2 {
typedef string mystring2;
typedef mylong1 mylong2;
module identifier3 {
typedef mylong1 long_from_module_1;
typedef mystring2 string_from_module_2;
typedef mylong2 long_from_module_1_2;
};
};
};
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11 ETSI ES 201 873-8 V4.8.1 (2021-06)

TTCN EXAMPLE:
module identifier1 {
type long mylong1;
}
module identifier1__identifier2 {
import from identifier1 all;
type iso8859string mystring2;
type identifier1.mylong1 mylong2;
}
module identifier1__identifier2__identifier3 {
import from identifier1 all;
import from identifier1__identifier2 all;

type identifier1.mylong1 long_from_module_1;
type identifier1__identifier2.mystring2 string_from_module_2;
type identifier1__identifier2.mylong2 long_from_module_1_2;
};
7.2 Importing interface declaration
Interfaces are flattened and all interface definitions are stored in one group. In contrast to interfaces in IDL, groups in
TTCN-3 do not create a scope. Therefore, prefixes for all identifiers of type definitions inside of the interface shall be
used, which are a combination of the interface name and two underscores as the prefix.
Import of single interface definitions from other modules via the importing group statement is possible. This can be
used if inheritance is used in the IDL specification.
For each interface, a procedure-based port type is defined for the test specification. It is associated with signatures
translated from attributes and operations of the interface.
An IDL attribute is mapped to two signatures: one for the setting of a value and one for getting it. These signatures have
names composed of the prefix (interface name and two underscores), attribute name and the word "Set" (except for
"readonly") or "Get" correspondingly.
Since an interface can be used in operation parameters to pass object references, an address type is also declared in the
data part - the concrete implementation is left to the user. Components are used as collection of interfaces or objects.
IDL EXAMPLE:
interface identifier {
attribute long attributeId ;
void operationname ( in string param_value ) raises ( ExceptionType ) ;
... other body definitions ...
};
TTCN EXAMPLE:
group identifierInterface {
signature identifier__attributeIdGet () return long
exception ( . /* and all system exceptions defined in clause 9 */ );
signature identifier__attributeIdSet (in long identifier__attributeId)
exception ( . /* and all system exceptions defined in clause 9 */ );

signature identifier__operationname ( in iso8859string identifier__param_value )
exception ( ExceptionType, . /* and all system exceptions defined in clause 9 */ ) ;

...other body definitions ...
type port identifier procedure { . }
type charstring identifierObject; /* a possible definition for the address type */
type identifierObject address;
}
Interface inheritance is executed by rolling out all inherited elements. Thus, they have to be handled as defined in the
interface itself. Multiple inheritance elements have to be inherited only once! As normally an inherited IDL interface
uses types defined in the module, usually it is essential to import the complete mapped TTCN-3 module. All inherited
elements have to be rolled out directly in the TTCN-3 group for the interface, even if the inheritance is multiple.
ETSI
12 ETSI ES 201 873-8 V4.8.1 (2021-06)
Forward references of interfaces are provided by forward referencing the according port of the interface. Local
interfaces are treated as normal interfaces. However it is recommend not to use forward references and to move a
TTCN-3 definition of the interface (group) to a place where a forward definition is used first time.
7.3 Importing value declaration
In contrast to type interface, the IDL type value has local operations that are not used outside the object, and are
therefore not relevant from the functional testing point of view. However, since the public attributes of value instances
are used to communicate object states, the IDL value type is mapped to the record type in TTCN-3.
The example below shows how to map valuetype and was used from clause 5.2.5 in [4].
IDL EXAMPLE:
valuetype EmployeeRecord {
// note this is not a CORBA::Object
// state definition
private string name;
private string email;
private string SSN;
// initializer
factory init(
in string name, in string SSN );
};
TTCN EXAMPLE:
type record EmployeeRecord {
iso8859string name,
iso8859string email,
iso8859string SSN
}
7.4 Importing constant declaration
Constant declarations can be transformed by use of literal (see table B.1) and operator mapping for floating-point and
integer values (see table 2).
Table 2: Operators for constant expressions
Operator IDL TTCN
Unary floating-point
Positive + +
Negative - -
Binary floating-point
Addition + +
Subtraction - -
Multiplication * *
Division / /
Unary integer
Positive + +
Negative - -
Bit-complement ~ not4b
Binary integer
Addition + +
Subtraction - -
Multiplication * *
Division / /
Modulo % mod
Shift left << <<
Shift right >> >>
Bitwise and & and4b
Bitwise or | or4b
Bitwise xor ^ xor4b
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IDL EXAMPLE:
const long number = 017; // 017 == 0xF == 15
const long size = ( ( number << 3 ) % 0x1F ) & 0123;

TTCN EXAMPLE:
const long number := "17"O;
const long size := ( ( number << 3 ) mod '1F'H ) and4b '0123'O;

8 Importing type declaration
8.0 General
Type declaration mapping will be shown in the following clauses.
A construct for naming data types and defining new types by using the keyword typedef is provided by IDL. This can
be done under TTCN-3 via the keyword type, too.
To enhance readability and to provide a clear distinction, mapped IDL data types get the prefix IDL and the extension
attribute "variant" as done in TTCN-3 for type IDLfixed (see clause E.2.3.0 in ETSI ES 201 873-1 [1]).
8.1 IDL basic types
8.1.0 General approach
IDL basic data types are mapped to predefined or useful types in TTCN-3.
8.1.1 Integer and floating-point types
Integer and floating-point types are mapped onto the corresponding useful types short, unsignedshort, long,
unsignedlong, longlong, unsignedlonglong, IEEE754float, IEEE754double, and IEEE754extdouble.
IDL EXAMPLE:
const long  size    = ( ( number << 3 ) % 0x1F ) & 0123;
const float  decimal  = 15.7;

TTCN EXAMPLE:
const long      size   := ( ( number << 3 ) mod '1F'H ) and4b '0123'O;
const IEEE754float  decimal := 15.7;

8.1.2 Char and wide char type
The IDL char and wide char type represent a single and wide character. They are mapped to the self defined type
iso8859char and type uchar.
IDL EXAMPLE:
const char letter   = 'ABCD';
const wchar wideLetter = L'ABCD';

TTCN EXAMPLE:
type universal charstring uchar length(1);
type uchar iso8859char (char ( 0,0,0,0 ) . char ( 0,0,0,255)) with { variant "8 bit" };

const iso8859char letter := char ( 65, 66, 67, 68 );
const uchar wideLetter := char ( 65, 66, 67, 68 );

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8.1.3 Boolean type
The IDL boolean type is equivalent to the TTCN-3 boolean type.
IDL EXAMPLE:
const boolean isValid = TRUE;
TTCN EXAMPLE:
const boolean isValid = true;
8.1.4 Octet type
Octet cannot be mapped onto an integer type because it has the special feature that it will not change its internal
ordering if transferred between different system architectures. To represent it octet is mapped to octetstring.
IDL EXAMPLE:
const octet data = 0x55;
TTCN EXAMPLE:
const octetstring data = '55'H

8.1.5 Any type
The IDL any type is mapped onto anytype in TTCN-3 which was especially introduced for this mapping.
IDL EXAMPLE:
typedef any AllTypes;
TTCN EXAMPLE:
type anytype AllTypes;
8.2 Constructed types
8.2.0 General approach
IDL provides the three constructed types struct, union, and enum. Recursive construction of types is only permitted
with the sequence template.
8.2.1 Struct
struct is used to collect ordered data in one place where it is mapped onto record in TTCN-3.
IDL EXAMPLE:
typedef struct NC {
string id;
string kind;
} NameComponent;
TTCN EXAMPLE:
type record NameComponent {
iso8859string id,
iso8859string kind
}
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8.2.2 Discriminated unions
In IDL, unions are discriminated to determine the actual type. Therefore, a record type is used, which contains two
members. The first one stores the discriminator information using an enumeration type. The second member is a
TTCN-3 union type which members are defined according to the specified IDL union members.
In addition, two types are defined to express the link between discriminator's type and union's type: a type to reflect the
discriminating type of a union and an enumeration to distinguish the discriminated cases. Using the information
provided by these type definitions, the marshalling/unmarshalling for discriminated unions is possible in an
unambiguous manner: to encode or decode a union value, the value of the kind field to resolve the corresponding
chosen option and calculate then the real value for the discriminator by resolving this value in the discriminator
enumeration shall be used.
IDL EXAMPLE 1:
union MyUnion switch( long ) {
case 0 : boolean b;
case 1 : char c;
case 2 : octet o;
case 3 : short s; };
TTCN EXAMPLE 1:
type long MyUnion__Switch;
type union MyUnionType {
boolean b,
iso8859string c,
octetstring o,
short s }
type enumerated MyUnionEnumType {
boolean_b, iso8859string_c, octetstring_o, short_s
}
type record MyUnion {
MyUnionEnumType kind,
MyUnionType value
}
IDL EXAMPLE 2:
Enum MyDiscr {
BOOLEAN_DISCR,
CHAR_DISCR,
OCTET_DISCR,
SEQ_DISCR,
SHORT_DISCR
};
union MyUnion switch( MyDiscr ) {
case BOOLEAN_DISCR : boolean b;
case SHORT_DISCR : short s;
};
TTCN EXAMPLE 2:
type enumerated MyDiscr {
BOOLEAN_DISCR, CHAR_DISCR, OCTET_DISCR, SEQ_DISCR, SHORT_DISCR
}
type MyDiscr MyUnion__Switch;
type enumerated MyUnion__CasesType {
case_BOOLEAN_DISCR,
case_SHORT_DISCR
}
type union MyUnionType {
boolean b,
short s
}
type enumerated MyUnionEnumType {
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boolean_b,
short_s
}
type record MyUnion {
MyUnionEnumType kind_,
MyUnionType value_
}
8.2.3 Enumerations
Enumerations are equally defined in IDL and TTCN-3.
IDL EXAMPLE:
enum NotFoundReason {
missing_node,
not_context,
not_object };
TTCN EXAMPLE:
type enumerated NotFoundReason {
missing_node,
not_context,
not_object }
8.3 Template types
8.3.0 General approach
IDL supports the template types sequence, string, wide string and fixed type.
8.3.1 Sequence
IDL sequence is mapped to record of in TTCN-3 to maintain order and to allow unbounded sequences.
IDL EXAMPLE 1:
typedef sequence Name;

TTCN EXAMPLE 1:
type record of NameComponent Name;

IDL sequences with a specified maximum size are mapped to record of with limited number of elements to maintain
order and restrict the maximum number of elements.
IDL EXAMPLE 2:
typedef sequence Name;

TTCN EXAMPLE 2:
type record length (0, maximum_size-1) of NameComponent Name;

8.3.2 String and wstring
string and wstring types are sequences of char and wchar. Therefore, string and wstring are mapped to the useful
type iso8859string and universal charstring.
IDL EXAMPLE:
const string name =    "My String";
const wstring wideName = L"My String";

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TTCN EXAMPLE:
const iso8859string name := "My String";
const universal charstring wideName := "My String";

8.3.3 Fixed types
The fixed type represents a fixed-point decimal number. It is mapped to the corresponding useful type IDLfixed in
TTCN-3 (see clause E.2.3.0 in ETSI ES 201 873-1 [1]).
IDL EXAMPLE:
typedef fixed<12,7> myFix;
TTCN EXAMPLE:
template IDLfixed myFixTemplate := { 12, 7, ? }; // e.g. in module definition part
var IDLfixed myFix := { 12, 7, "12345.1234567" }; // e.g. in module control part

8.4 Complex declarator
8.4.0 General approach
The last kind of type declarators are the complex array and native types.
8.4.1 Arrays
IDL array is equal to the TTCN-3 array type.
IDL EXAMPLE:
typedef long NumberList[100];
TTCN EXAMPLE:
type long NumberList[100];
8.4.2 Native types
Native types are used to allow implementation of dependent types. TTCN-3 provides the type address to address
entities inside a SUT. Hence, address can be used for mapping of type native and concrete implementation is left to the
user.
IDL EXAMPLE:
typedef native MyNativeVariable;

TTCN EXAMPLE:
type MyNativeVariable address;

9 Importing exception declaration
In IDL, exceptions are used in conjunction with operations to handle exceptional conditions during an operation call.
Thus, a special struct-like exception type is provided which has to be associated with each operation that can trigger
this exception. TTCN-3 also supports the use of exceptions with procedure calls by binding it to signature definitions.
However, it provides no special exception type. Hence, exceptions are defined by using type record.
A definition of an exception is shown in the following example. The use of exception binding in signature definitions
and exception catching is shown in the context of operation declaration.
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IDL EXAMPLE:
exception NotFoundException {
NotFoundReason why;
Name rest_of_name; };
TTCN EXAMPLE:
// definition of an exception type
type record NotFoundException {
NotFoundReason why,
Name rest_of_name }
// definition of a template for the
// defined exception type
template NotFoundException
NotFoundExceptionTemplate ( NotFoundReason reason, Name name ) := {
why := reason,
rest_of_name := name }
In addition to user defined exceptions, there are CORBA system exceptions defined in chapter 4 in [4]. In order to
make them available for use in TTCN-3, the following definitions are to be used:
// CORBA system exceptions
type record UNKNOWN{}  // the unknown type record
type record BAD_PARAM{}  // an invalid parameter was passed
type record NO_MEMORY{}  // dynamic memory allocation failure
type record IMP_LIMIT{}  // violated implementation limit
type record COMM_FAILURE{}  // communication failure
type record INV_OBJREF{}  // invalid object reference
type record NO_PERMISSION{} // no permission for attempted op.
type record INTERNAL{}  // ORB internal error
type record MARSHAL{}  // error marshaling param/result
type record INITIALIZE{}  // ORB initialization fa
...