Lecture Notes in Computer Science 3472

16 TTCN-3 483
user. The CD, SA and PA entities are instantiated on each device because their
implementation may differ depending on their underlying heterogeneous devices.
16.5.2 Test Control Interfaces
The TTCN-3 Control Interfaces provide a standardized adaptation for the management
and the handling of test components and for the encoding/decoding of
a test system to a particular test platform.
The 6th part of the ETSI TTCN-3 standard defines the interaction between
three main entities: Test Management (TM), Test Component Handler (CH)
and Coder/Decoder (CoDec). The test can be distributed over many test hosts
and different test behaviors can be executed simultaneously. As it is conceived
within the standard, on each host, an instance of the test system is created. The
Test Execution (TE) must be distributed on each host with its own codec (CD),
System Adapter (SA) and Platform Adapter (PA). The Component Handling
(CH) supplies the communication between the test components created, that run
on different hosts. The Test Management coordinates and manages the execution
of the test.
The interaction between the main entities is defined as a set of interfaces. The
API, conceived within the interfaces, defines operations which the entities either
provide or use. For this reason, there are two classes of interfaces: provided and
required. Provided interfaces contain operations which are offered by an entity;
the required interfaces contain operations that an entity expects from the other
entities.
Data Types The TTCN-3 data described in the test module must be transformed
into concrete data values which are handled by the entities implementing
the test system. TE contains the data values which are generated at compilation.
In order to maintain a common data model, the TCI standard defines the Abstract
Data Type Model, which describes the interfaces that handle the TTCN-3
data from TE. Each abstract data type has associated a set of operations which
defines its functionality.
The Abstract Data Type Model contains two parts: the data type Type,which
represents all TTCN-3 types of a module, and data types that represent TTCN-3
values (instances of TTCN-3 types). All TTCN-3 types provide the same interface.
One may obtain for a type the module where it was defined, its name
or class and the type of encoding. Any type can be instantiated by using the
newInstance method. The different types of values, which can appear in a TE,
are presented in Figure 1.5.
All types of values inherit the Value type and provide the core operations:
getValueEncoding, getType and notPresent. TheValue types represent the
mapping of the abstract TTCN-3 values to concrete ones. There are three categories
of values: a) basic types (integer, float, boolean etc), b) string based values
(hexstring, octetstring, charstring etc) and c) structured types (union, record,
verdict). All of them provide additional operations (besides the operations extended
from Value) to access their functionality.