class ara::rds::IEEE1722DatagramNTSCF

The class ara::rds::IEEE1722DatagramNTSCF represents the data structure for IEEE 1722 NTSCF control datagrams within the Raw Data Stream module SWS RawDataStream “Specification of Raw Data Stream”. It encapsulates protocol-specific fields such as sequence number, address information, and unique identifiers in protected attributes available to specialized datagram classes. A safe lifecycle in polymorphic use is ensured via the virtual destructor [SWS_RDS_90310]. The most critical constraint is that destruction must strictly be non-throwing and optional fields must be checked for presence before access.

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Context

Within the AUTOSAR Adaptive module rds (Raw Data Stream), the class ara::rds::IEEE1722DatagramNTSCF represents the structure of an IEEE 1722 datagram in NTSCF format (Non-Time-Synchronous Control Format) according to SWS RawDataStream “Specification of Raw Data Stream”. The class bundles protocol fields specified for the exchange of non-time-critical control and payload streams. The header file #include "ara/rds/raw_data_stream_IEEE1722.h" declares the class in namespace ara::rds. The specified components include the unique stream identifier unique_id [SWS_RDS_90309], the sequence number sequenceNum [SWS_RDS_90307], as well as the length and address information ntscf_data_length and mac_address [SWS_RDS_90306], [SWS_RDS_90308].

It is notable that all data elements have access protection protected. As an interpretation, it can be derived from this that the class serves as a fundamental base class for derived, protocol-specific datagram structures and is presumably not intended for direct instantiation by regular application logic. Question Q-10e9faa973973eda (open)

Lifecycle

The lifecycle of ara::rds::IEEE1722DatagramNTSCF is designed for safe operation in object-oriented inheritance hierarchies. The central element is the virtual destructor ~IEEE1722DatagramNTSCF() noexcept according to [SWS_RDS_90310]. Virtualness guarantees that upon destruction of a derived instance via a pointer to the base class, the destructor chain is executed completely and correctly.

The declaration with noexcept [SWS_RDS_90310] ensures that destruction of the object throws no exceptions under any circumstances. This conforms to the core requirements of modern C++ resource management and guarantees exception safety in the event of an error.

Public constructors are not listed in the scope of the specification. Object creation is therefore likely performed either by derived classes during their initialization or via internal creation mechanisms of the Raw Data Stream module. Question Q-4a0e75e3e565d2d5 (open) The class does not possess fixed states or an internal state machine; from creation to destruction, the object remains in a consistent state as an information carrier.

Usage Path

The class is typically used in the course of processing control data streams according to IEEE 1722. Derived classes or components of the raw data stream framework use the protected attributes to serialize or deserialize the transmitted packets. The attributes are defined as primitive integer types or as ara::core::Optional. The typical processing chain is divided into the following steps:

• Stream identification: Based on unique_id [SWS_RDS_90309], it is checked to which logical data stream the datagram belongs.
• Sequence check: Via the sequence number sequenceNum [SWS_RDS_90307], it can be determined whether packets arrived in the expected order or whether packet loss has occurred.
• Length and address evaluation: Via fields ntscf_data_length and mac_address [SWS_RDS_90306], [SWS_RDS_90308], the size of the payload is determined and the destination or source address is evaluated.

After evaluation of the payload, the usage path ends with the release of the instance via the virtual destructor [SWS_RDS_90310].

Error Scenarios

Due to the nature of ara::rds::IEEE1722DatagramNTSCF as a data structure and base class, errors do not occur in the form of method return codes, but concern preconditions during data access and destruction:

• Unchecked access to optional fields: Attributes such as sequenceNum [SWS_RDS_90307] and unique_id [SWS_RDS_90309] are declared as ara::core::Optional. Access without prior checking using has_value() leads to runtime errors or undefined behavior in case of incomplete packets.
• Violation of the noexcept guarantee in the destructor: Since the destructor is specified with noexcept [SWS_RDS_90310], any exception thrown during cleanup in derived classes and not handled locally leads to immediate program termination via std::terminate.
• Inconsistent length specifications: If the value of ntscf_data_length [SWS_RDS_90306], [SWS_RDS_90308] does not match the actual buffer size of the network driver, buffer overflows or incomplete reading can occur during data processing.