Add flatbuffers component

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

@@ -92,6 +92,16 @@ 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: ASIL_B
+   :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.
+
 .. 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) 2025 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:: JSON
+   :id: comp__baselibs_flatbuffers
+   :security: YES
+   :safety:  ASIL_B
+   :status: invalid

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

@@ -0,0 +1,198 @@
+..
+   # *******************************************************************************
+   # Copyright (c) 2025 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.
+
+Additionally, the library introduces FlatBuffers binary configuration format to replace JSON-based
+module configuration. FlatBuffers provides zero-copy access, schema validation, and access code
+generation for C++, Rust, and further languages. The approach eliminates the need for runtime
+parsing and accelerates module startup times. Safety certification covers ``flatc`` tool
+qualification, runtime library verification, and module-level testing of generated code.
+
+
+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
+
+Given its cross-cutting nature, this architectural decision shall be done early in the project.
+
+
+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.
+
+
+Basic Functionality
+===================
+
+The ``flatc`` compiler shall generate code for serializing, accessing, and verifying
+FlatBuffers binary data. Code generation shall be provided for C++ and Rust at ASIL-B level
+and other languages as needed at QM level (e.g. Python).
+
+The FlatBuffers-Library shall provide services for serialization, zero-copy access of
+FlatBuffers binary data, and structural verification of buffers. The library shall also support
+loading FlatBuffers binary files and optionally provide common buffer identification and version
+checking mechanisms.
+
+Note: FlatBuffers verification mechanism validates structural well-formedness only (e.g. offsets, vtables,
+field boundaries), not payload data integrity.
+
+Module configuration shall use FlatBuffers binary format for read-only configuration scenarios to
+achieve aggressive start-up time requirements.
+
+.. _flatbuffers_overview:
+
+Implementation
+--------------
+
+.. figure:: _assets/flatbuffers_overview.drawio.svg
+   :alt: FlatBuffers overview
+   :align: center
+   :width: 80%
+
+| FlatBuffers schema files (``config.fbs``) define 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 cross-platform data binary from schema (``config.fbs``) and JSON (``config.json``) input.
+| Runtime access operates directly on binary config data (``config.bin``) without parsing (lazy loading).
+| The ``flatc`` compiler can convert binary config data (``config.bin``) back to JSON using the schema (``config.fbs``) for debugging purposes.
+
+Schema Evolution
+^^^^^^^^^^^^^^^^
+
+Backward compatibility through:
+   - Optional fields for new parameters
+   - Default values for missing fields
+   - Controlled field deprecation
+
+Schema 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)
+
+Build Integration
+-----------------
+
+Build system integration shall provide reusable rules for:
+   - Binary configuration file generation from module specific schema and user-provided JSON data
+   - Reverse conversion from binary to JSON for debugging purposes
+
+Binary Config Loading
+---------------------
+
+The FlatBuffers-Library provides a unified interface for binary data file loading
+(see :ref:`FlatBuffers overview <flatbuffers_overview>`).
+
+
+Backwards Compatibility
+=======================
+
+Switching from JSON to FlatBuffers for module configuration is not backwards compatible.
+
+
+Security Impact
+===============
+
+No change expected when compared to JSON based configuration approach.
+
+
+Safety Impact
+=============
+
+**Tool Qualification**: ``flatc`` compiler qualification shall be limited to 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.
+
+
+Future Extensions
+=================
+
+
+Footnotes
+=========
+
+.. [#flatbuffers] https://google.github.io/flatbuffers/