DDS Gateway communication feature

docs/features/communication/dds_gateway/index.rst

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+..
+   # *******************************************************************************
+   # Copyright (c) 2024 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
+   # *******************************************************************************
+
+DDS Gateway
+===========
+
+.. document:: DDS-Gateway
+   :id: doc__dds_gateway
+   :status: valid
+   :safety: ASIL_B
+   :tags: contribution_request, feature_request
+   :security: YES
+   :realizes: wp__feat_request
+
+
+Overview
+--------
+
+The DDS Gateway introduces a communication bridge within the S-CORE communication stack.
+It enables controlled and configurable data exchange between ``mw::com (LoLa)`` (intra-ECU 
+communication via IPC binding) and DDS-based systems (inter-ECU
+communication), allowing integration with distributed DDS environments
+while preserving existing application implementations.
+
+Architecture Concept
+--------------------
+The DDS Gateway acts as a centralized communication bridge between local
+``mw::com (LoLa)`` communication and DDS domains, enabling inter-ECU
+communication between ``mw::com`` participants via DDS transport.
+
+::
+
+   ==============================        ==============================
+              ECU 1                              ECU 2
+   ==============================        ==============================
+
+   +-------------------------+           +-------------------------+
+   |     Application A       |           |     Application B       |
+   |   (mw::com LoLa)        |           |   (mw::com LoLa)        |
+   +-----------+-------------+           +-----------+-------------+
+               |                                     ^
+               |  mw::com (LoLa - IPC)               | mw::com (LoLa - IPC)
+               v                                     |
+       +---------------------+               +---------------------+
+       |     DDS Gateway     |               |     DDS Gateway     |
+       |       (ECU 1)       |               |       (ECU 2)       |
+       +----------+----------+               +----------+----------+
+                  |                                     ^
+                  |                                     |
+                  v                                     |
+         ===================   DDS NETWORK   ===================
+                  |                                     ^
+      ==============================                    | 
+               ECU 3                                    |
+      ==============================                    |
+                  |                                     |
+                  v                                     |
+       +---------------------+                          |
+       |   DDS Application   |--------------------------+
+       |     (optional)      |
+       +---------------------+
+
+Each DDS Gateway instance connects to:
+- Local ``mw::com (LoLa)`` participants (IPC binding)
+- A DDS domain for inter-ECU communication
+
+The gateway is responsible for:
+
+- Translating data in both directions between ``mw::com`` and DDS representations  
+- Routing data across DDS domains
+- configure QOS on DDS for each route 
+- Applying  E2E protection  
+
+
+Scope
+-----
+The DDS Gateway provides:
+
+- Bridging between ``mw::com (LoLa)`` and DDS via the gateway:
+   - ``mw::com (LoLa)`` → DDS GW → ``mw::com (LoLa)`` (inter-ECU communication via DDS)
+   - ``mw::com (LoLa)`` → DDS GW → DDS applications
+   - DDS applications → DDS GW → ``mw::com (LoLa)``
+
+- Configurable routing:
+
+  - Mapping between ``mw::com`` events(TBD for fields and methods) and DDS topics
+  - Support for DDS domain-based routing
+
+- Dynamic Type handling:
+
+  - Runtime type definition via configuration or via dynamic library
+  - No dependency on DDS IDL generation
+  - Enables data translation and consistent serialization across middleware boundaries
+  - Supports DDS standard encodings (e.g., XCDR1 and XCDR2) for interoperability
+
+- End-to-End (E2E) protection:
+
+  - Centralized handling of Counter, CRC, and DataID
+  - Validation and protection configurable per route
+
+- DDS stack abstraction:
+
+  - Pluggable DDS implementations via defined interfaces
+
+- Execution and performance model:
+
+  - Asynchronous processing using internal worker queues  
+  - Support for configurable priority-based routing  
+  - High-priority routes can be processed with dedicated queues and worker pools to achieve low-latency data delivery  
+  - Normal-priority routes are handled via standard processing queues  
+  - Priority configuration is defined per route  
+
+- DDS QoS configurability:
+
+  - Ability to configure DDS Quality of Service (QoS) policies per route  
+  - Enables tuning of reliability, durability, and latency behavior based on use case  
+
+Motivation
+----------
+
+S-CORE currently focuses on local communication via ``mw::com (LoLa)`` but does
+not provide a standardized mechanism for inter-ECU communication using DDS-based
+systems.
+
+In mixed middleware environments:
+
+- Integration with DDS requires custom adapters  
+- Applications may need to embed DDS logic, reducing abstraction  
+- Communication with native DDS applications is not standardized  
+- Inter-ECU communication between ``mw::com`` participants via DDS is not standardized  
+- Multi-domain DDS setups are difficult to manage consistently    
+
+
+The DDS Gateway addresses these challenges by introducing a centralized,
+configurable component responsible for bridging and routing communication
+across middleware boundaries.
+
+Key Value
+---------
+
+- Standardized integration with DDS systems  
+- Direct interoperability with native DDS applications via the gateway  
+- Standardized inter-ECU communication between ``mw::com`` participants via DDS  
+- Clean separation between ``mw::com (LoLa)`` and DDS  
+- Reduced integration effort  
+- Support for distributed and multi-domain systems  
+
+- Performance and determinism:
+
+  - Low-latency processing for high-priority data flows  
+  - Controlled execution via configurable worker queues  
+  - Predictable behavior for mixed criticality communication  
+
+- Interoperability across heterogeneous systems:
+
+  - Enables communication between systems with different architectures
+    (e.g., 32-bit / 64-bit, different endianness)
+  - Ensures consistent data representation via Dynamic Type handling  
+
+- Centralized handling of safety (E2E) and type management  
+
+Reference
+---------
+
+The detailed Feature Request is available here:
+
+- DDS Gateway Feature Request:https://github.com/eclipse-score/score/issues/2726