Add flatbuffers component

docs/features/baselibs/docs/requirements/index.rst

@@ -92,6 +92,20 @@ Requirements
 
    The base libraries shall provide a JSON-Library with parsing functionality.
 
+.. feat_req:: FlatBuffers-Library
+   :id: feat_req__baselibs__flatbuffers_library
+   :reqtype: Functional
+   :security: NO
+   :safety: QM
+   :satisfies: stkh_req__functional_req__base_libraries
+   :status: valid
+
+   The base libraries shall provide a FlatBuffers-Library with serialization, read access, and structural verification of FlatBuffers data.
+
+   .. note::
+      FlatBuffers-Library provides both ASIL-B and QM compliant functionality depending on the programming language,
+      the separation is done on component level.
+
 .. feat_req:: Exception-Free Development Support
    :id: feat_req__baselibs__result_library
    :reqtype: Functional

docs/modules/baselibs/flatbuffers/docs/architecture/index.rst

@@ -0,0 +1,24 @@
+..
+   # *******************************************************************************
+   # Copyright (c) 2026 Contributors to the Eclipse Foundation
+   #
+   # See the NOTICE file(s) distributed with this work for additional
+   # information regarding copyright ownership.
+   #
+   # This program and the accompanying materials are made available under the
+   # terms of the Apache License Version 2.0 which is available at
+   # https://www.apache.org/licenses/LICENSE-2.0
+   #
+   # SPDX-License-Identifier: Apache-2.0
+   # *******************************************************************************
+
+FlatBuffers Component Architecture
+==================================
+
+.. To be created. Link from comp_req to comp is mandatory for score metamodel check.
+
+.. comp:: FlatBuffers
+   :id: comp__baselibs_flatbuffers
+   :security: YES
+   :safety:  ASIL_B
+   :status: invalid

docs/modules/baselibs/flatbuffers/docs/index.rst

@@ -0,0 +1,234 @@
+..
+   # *******************************************************************************
+   # Copyright (c) 2026 Contributors to the Eclipse Foundation
+   #
+   # See the NOTICE file(s) distributed with this work for additional
+   # information regarding copyright ownership.
+   #
+   # This program and the accompanying materials are made available under the
+   # terms of the Apache License Version 2.0 which is available at
+   # https://www.apache.org/licenses/LICENSE-2.0
+   #
+   # SPDX-License-Identifier: Apache-2.0
+   # *******************************************************************************
+
+FlatBuffers-Library
+===================
+
+.. document:: FlatBuffers-Library
+   :id: doc__flatbuffers
+   :status: valid
+   :safety: ASIL_B
+   :security: YES
+   :tags: component_request
+   :realizes: wp__cmpt_request
+
+
+.. toctree::
+   :hidden:
+
+   requirements/index.rst
+   architecture/index.rst
+
+
+Abstract
+========
+
+This component request proposes the integration of Google FlatBuffers [#flatbuffers]_ providing
+serialization, zero-copy read access, and structural verification of FlatBuffers data, as well as code
+generation via the ``flatc`` compiler.
+
+FlatBuffers provides zero-copy access, schema validation, and access code generation for C++, Rust,
+and further languages. Safety certification covers ``flatc`` tool qualification, runtime library verification,
+and module-level testing of generated code.
+
+The introduction is proposed for the following use case:
+
+- Module configuration: FlatBuffers binary format for read-only configuration scenarios to achieve
+  aggressive start-up time requirements, as it eliminates the need for runtime parsing.
+
+
+Motivation
+==========
+
+Module-specific configuration is a cross-cutting concern that impacts system startup time and
+development efficiency. For read-only configuration scenarios, runtime parsing approaches can
+limit startup performance in time-critical applications.
+
+The FlatBuffers binary configuration approach addresses these engineering challenges by:
+   - Eliminating the need for runtime parsing to meet aggressive startup time requirements
+   - Providing compile-time type safety through generated access code
+   - Reducing development effort through automated access code generation
+   - Ensuring schema validation at build time
+
+
+Rationale
+=========
+
+Real-world experience with complex modules (e.g. diagnostics, SOME/IP) demonstrates that read-only
+configuration scenarios benefit significantly from zero-copy access patterns. For these use cases,
+FlatBuffers is ideal as it allows zero-copy data access. The schema-driven code generation further
+accelerates development by providing type-safe access patterns, reducing both implementation effort
+and the potential for configuration-related runtime errors.
+
+
+Specification
+=============
+
+The ``flatc`` compiler of FlatBuffers [#flatbuffers]_ generates code for serializing, accessing, and verifying
+FlatBuffers binary data.
+
+The FlatBuffers-Library provides features defined in :need:`feat_req__baselibs__flatbuffers_library`.
+Note: The FlatBuffers verification mechanism validates structural well-formedness only (e.g. offsets, vtables,
+field boundaries), not payload data integrity. Therefore, :need:`aou_req__flatbuffers__data_integrity` needs
+to be ensured by the user.
+
+In addition, opt-in common buffer identification functionality is provided to allow identification of a buffer
+without further schema information. For details, refer to :need:`comp_req__flatbuffers__buffer_identification`.
+
+Schema Evolution
+----------------
+
+Backward compatibility is maintained through:
+   - Optional fields for new parameters
+   - Default values for missing fields
+   - Controlled field deprecation
+
+Build Integration
+-----------------
+
+Build system integration provides reusable rules for:
+   - Buffer serialization from module-specific schema and provided JSON data
+   - Reverse conversion from binary to JSON for debugging purposes
+
+Supported use cases
+-------------------
+
+Module configuration
+^^^^^^^^^^^^^^^^^^^^
+
+.. figure:: _assets/config_use_case_overview.drawio.svg
+   :alt: Configuration use case overview
+   :align: center
+   :width: 70%
+
+| FlatBuffers schema files (``config.fbs``) define the configuration structure using Interface Definition Language (IDL).
+| The ``flatc`` compiler generates C++ or Rust access code from these schemas (``config.fbs``).
+| The ``flatc`` compiler generates a cross-platform data binary from the schema (``config.fbs``) and JSON (``config.json``) input.
+| Runtime access operates directly on the binary config data loaded from ``config.bin`` without parsing.
+| The ``flatc`` compiler can convert binary config data (``config.bin``) back to JSON using the schema (``config.fbs``) for debugging purposes.
+
+
+Identification and Versioning
+"""""""""""""""""""""""""""""
+
+FlatBuffers binary files do not contain embedded schema information. Schema identification requires:
+   - Embedded version fields in the schema root table
+   - File naming conventions (e.g., config_v1.2.bin)
+
+Future use cases
+----------------
+
+Future use cases are not yet in scope and may require extension of the existing module requirements
+and assumptions of use.
+
+Storage format (read/write/modify)
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. figure:: _assets/storage_format_use_case_overview.drawio.svg
+   :alt: Storage format use case overview
+   :align: center
+   :width: 70%
+
+| FlatBuffers schema files (``storage.fbs``) define the storage structure using Interface Definition Language (IDL).
+| The ``flatc`` compiler generates C++ or Rust access code from these schemas (``storage.fbs``).
+| Runtime access/modify* operates directly on binary data loaded from the binary data file (``data.bin``).
+| Runtime write serializes a new buffer that can be stored as a binary data file (``data.bin``).
+
+FlatBuffers is applicable as a storage format when reads significantly outnumber writes and write
+latency is not time-critical. Serialization rewrites the entire buffer, making it unsuitable for
+high-frequency write scenarios. Long-lived storage further benefits from schema evolution,
+allowing stored files to remain compatible across software updates without requiring a format migration step.
+
+Payload format (communication)
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. figure:: _assets/payload_format_use_case_overview.drawio.svg
+   :alt: Payload format use case overview
+   :align: center
+   :width: 50%
+
+| FlatBuffers schema files (``payload.fbs``) define the payload structure using Interface Definition Language (IDL).
+| The ``flatc`` compiler generates C++ or Rust access code from these schemas (``payload.fbs``).
+| Runtime sender serializes data into a FlatBuffers buffer (``payload``) and transmits it.
+| Runtime receiver accesses data directly from the received buffer (``payload``).
+
+FlatBuffers is applicable as a payload format when message content is variable or sparse. Unlike
+fixed-size binary structs, FlatBuffers supports optional fields and unions, making it suitable for
+heterogeneous or extensible message types where not every field is present in every message.
+Schema evolution allows sender and receiver to evolve independently across software versions
+without requiring coordinated redeployment, which is relevant for interfaces with long maintenance
+lifetimes.
+
+However, each message transmission comes at the cost of serialization, which adds overhead to
+communication on the sender side.
+
+
+Backwards Compatibility
+=======================
+
+Module configuration: Switching from JSON to FlatBuffers for module configuration is not backwards compatible.
+
+
+Security Impact
+===============
+
+Module configuration: No change expected when compared to the JSON-based configuration approach.
+
+
+Safety Impact
+=============
+
+**Tool Qualification**: ``flatc`` compiler qualification is limited to the buffer serialization use case.
+Brief qualification is supplemented by module-specific validation.
+
+**Verification Runtime Library**: Footprint when excluding verifier/builder classes
+   - C++: 12 headers, ~250 LOC (incl. comments), standard library only
+   - Rust: 11 files, ~150 LOC (incl. comments), core/alloc only (assumes std/serialize features disabled)
+
+**Verification Generated Code**: Module-level verification is equivalent to handwritten access code verification.
+Module testing contributes to ``flatc`` tool validation for specific schemas.
+Test from configuration data (JSON) to value verification in access APIs.
+
+
+License Impact
+==============
+
+None. FlatBuffers is licensed under the Apache License Version 2.0.
+
+
+How to Teach This
+=================
+
+Developer adoption requires practical examples and reusable patterns.
+The FlatBuffers-Library should provide examples for reference implementations.
+
+
+Rejected Ideas
+==============
+
+**Protocol Buffers**: Requires runtime parsing and memory allocation, defeating startup time objectives.
+
+**Custom binary formats**: Higher development and maintenance overhead compared to proven FlatBuffers ecosystem.
+
+
+Open Issues
+===========
+
+No open issues identified yet.
+
+
+Footnotes
+=========
+
+.. [#flatbuffers] https://google.github.io/flatbuffers/