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3 changes: 3 additions & 0 deletions .gitignore
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Expand Up @@ -34,6 +34,9 @@
# build folder for ESP-IDF
build/

# submodule configuration
components/rtps_embedded/thirdparty/Micro-CDR/include/ucdr/config.h

# we only version sdkconfig.defaults
sdkconfig
sdkconfig.old
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3 changes: 3 additions & 0 deletions .gitmodules
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Expand Up @@ -37,3 +37,6 @@
[submodule "components/gfps_service/detail/nearby"]
path = components/gfps_service/detail/nearby
url = https://github.com/esp-cpp/nearby
[submodule "components/rtps_embedded/thirdparty/Micro-CDR"]
path = components/rtps_embedded/thirdparty/Micro-CDR
url = git@github.com:esp-cpp/Micro-CDR.git
Comment on lines +40 to +42
30 changes: 30 additions & 0 deletions components/rtps_embedded/CMakeLists.txt
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idf_component_register(
SRCS
"src/ThreadPool.cpp"
"src/communication/EsppTransport.cpp"
"src/discovery/ParticipantProxyData.cpp"
"src/discovery/SEDPAgent.cpp"
"src/discovery/SPDPAgent.cpp"
"src/discovery/TopicData.cpp"
"src/entities/Domain.cpp"
"src/entities/Participant.cpp"
"src/entities/Reader.cpp"
"src/entities/StatelessReader.cpp"
"src/entities/Writer.cpp"
"src/messages/MessageReceiver.cpp"
"src/messages/MessageTypes.cpp"
"src/utils/Diagnostics.cpp"
"thirdparty/Micro-CDR/src/c/common.c"
"thirdparty/Micro-CDR/src/c/types/array.c"
"thirdparty/Micro-CDR/src/c/types/basic.c"
"thirdparty/Micro-CDR/src/c/types/sequence.c"
"thirdparty/Micro-CDR/src/c/types/string.c"
INCLUDE_DIRS
"include"
"thirdparty/Micro-CDR/include"
REQUIRES
base_component cdr task thread_pool socket
)
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# target_compile_features(${COMPONENT_LIB} PUBLIC cxx_std_17)
# target_compile_definitions(${COMPONENT_LIB} PUBLIC RTPS_CONFIG_HEADER=\"rtps/config_esp32.h\")
162 changes: 162 additions & 0 deletions components/rtps_embedded/README.md
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# rtps_embedded

ESPP component that integrates the [embeddedRTPS](https://github.com/embedded-software-laboratory/embeddedRTPS)
RTPS/DDS stack into the ESPP ecosystem.
Any platform that can build ESPP — including ESP32, Linux, and desktop PCs —
can use this component to discover and exchange typed messages with ROS 2 nodes
or any other DDS participant on the same network using the standard RTPS wire
protocol.

The original embeddedRTPS library has hard dependencies on FreeRTOS and lwIP.
`rtps_embedded` removes those dependencies by replacing all socket, task, and
synchronisation calls with ESPP's platform-agnostic `UdpSocket`, `Task`, and
`ThreadPool` primitives. When built for ESP32, ESPP uses FreeRTOS and lwIP
under the hood; on other platforms it uses the host OS equivalents — the RTPS
code itself is unchanged in either case.

---

## Architecture

```
user code
rtps::Domain — routes packets to participants; owns discovery threads
├── rtps::Participant — groups writers and readers
│ ├── rtps::Writer — publishes CacheChange samples
│ └── rtps::Reader — delivers samples to a user callback
├── rtps::ThreadPool — espp::ThreadPool workers that drain the four
│ incoming/outgoing meta/user traffic queues
└── rtps::EsppTransport — one espp::UdpSocket per open UDP port,
each with its own receive task
```

`EsppTransport` is the sole platform-specific adapter. It wraps ESPP's
`UdpSocket` and `Task`, which in turn map to:

| Build target | Socket backend | Task backend |
|---|---|---|
| ESP32 | lwIP (via ESP-IDF) | FreeRTOS |
| Linux / PC | POSIX sockets | `std::thread` |

---

## Quick-start

```cpp
#include "rtps/entities/Domain.h"

// 1. Construct the domain with the local interface IP.
rtps::Domain domain(local_ip);

// 2. Create a participant *before* completeInit().
rtps::Participant *part = domain.createParticipant();

// 3. Add user-defined writer and reader endpoints.
rtps::Writer *writer = domain.createWriter(*part, "my/topic",
"std_msgs::msg::String", false);
rtps::Reader *reader = domain.createReader(*part, "my/topic",
"std_msgs::msg::String", false);

// 4. Register a receive callback on the reader.
reader->registerCallback(
[](void *, const rtps::ReaderCacheChange &change) {
// process change.getData() / change.copyInto(...)
}, nullptr);

// 5. Start discovery (SPDP/SEDP) and worker threads.
domain.completeInit();

// 6. Publish a sample.
const char *payload = "hello";
writer->newChange(rtps::ChangeKind_t::ALIVE,
reinterpret_cast<const uint8_t *>(payload),
static_cast<rtps::DataSize_t>(strlen(payload) + 1));
```

> **Note**: `createParticipant()` **must** be called before `completeInit()`.
> No new participants can be added after init is complete.

---

## Configuration

Two built-in config headers are provided. Select one by defining
`RTPS_CONFIG_HEADER`, or let `include/rtps/config.h` pick automatically based
on the build target.

| Header | Target |
|---|---|
| [`include/rtps/config_esp32.h`](include/rtps/config_esp32.h) | ESP32 (ESP-IDF) |
| [`include/rtps/config_desktop.h`](include/rtps/config_desktop.h) | Linux / PC |

All tunable constants follow the same layout in both files:

| Constant | Default | Description |
|---|---|---|
| `DOMAIN_ID` | 0 | RTPS domain number (0–230 with UDP) |
| `MAX_NUM_PARTICIPANTS` | 1 | Participant pool size |
| `NUM_STATEFUL_WRITERS` | 5 | User writer endpoint pool |
| `NUM_STATEFUL_READERS` | 5 | User reader endpoint pool |
| `NUM_STATELESS_WRITERS` | 5 | Discovery writer endpoint pool |
| `NUM_STATELESS_READERS` | 5 | Discovery reader endpoint pool |
| `NUM_WRITERS_PER_PARTICIPANT` | 10 | Max writers per participant |
| `NUM_READERS_PER_PARTICIPANT` | 10 | Max readers per participant |
| `HISTORY_SIZE_STATEFUL` | 10 | Per-endpoint history depth |
| `THREAD_POOL_NUM_WRITERS` | 2 | Writer worker threads |
| `THREAD_POOL_NUM_READERS` | 2 | Reader worker threads |
| `THREAD_POOL_WRITER_STACKSIZE` | 4096 B | Writer task stack |
| `THREAD_POOL_READER_STACKSIZE` | 6144 B | Reader / UDP-receive task stack |
| `MAX_NUM_UDP_CONNECTIONS` | 10 | UDP socket pool size |
| `SPDP_RESEND_PERIOD_MS` | 2000 | Discovery announce period |
| `SF_WRITER_HB_PERIOD_MS` | 4000 | Reliable-writer heartbeat period |

The `OVERALL_HEAP_SIZE` constant at the bottom of that file estimates the
total stack RAM consumed by all internal tasks.

---

## ESPP component dependencies

| Component | Purpose |
|---|---|
| `base_component` | ESPP base class with integrated `espp::Logger` |
| `socket` | ESPP `UdpSocket` used by `EsppTransport` |
| `task` | ESPP `Task` for per-port UDP receive loops |
| `thread_pool` | ESPP `ThreadPool` for writer/reader workers |
| `cdr` | CDR serialization helpers |

These components abstract away all OS and network-stack details, so
`rtps_embedded` itself has no direct dependency on FreeRTOS, lwIP, or any
other platform library.

Third-party (vendored in `thirdparty/`):

| Library | Purpose |
|---|---|
| `Micro-CDR` | eProsima CDR (de)serialization for discovery messages |

---

## Example

See [`example/`](example/) for a two-node **initiator / responder** demo.

The same logic runs on any ESPP-supported platform. For ESP32, flash one board
as *Initiator* and a second as *Responder* via menuconfig
(`idf.py menuconfig → RTPS Example Configuration`). The initiator periodically
publishes numbered request messages; the responder echoes each message back on
the response topic.

Key menuconfig options (ESP32 example):

| Option | Description |
|---|---|
| `RTPS_EXAMPLE_ROLE` | `Initiator` or `Responder` |
| `RTPS_EXAMPLE_TOPIC_PREFIX` | Shared topic prefix (e.g. `espp/rtps_example`) |
| `RTPS_EXAMPLE_PUBLISH_PERIOD_MS` | Initiator publish interval |
| `ESP_WIFI_SSID` / `ESP_WIFI_PASSWORD` | Wi-Fi credentials |
21 changes: 21 additions & 0 deletions components/rtps_embedded/example/CMakeLists.txt
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# The following lines of boilerplate have to be in your project's CMakeLists
# in this exact order for cmake to work correctly
cmake_minimum_required(VERSION 3.20)

set(ENV{IDF_COMPONENT_MANAGER} "0")
include($ENV{IDF_PATH}/tools/cmake/project.cmake)

set(EXTRA_COMPONENT_DIRS
"../../../components/"
)

set(
COMPONENTS
"main esptool_py logger rtps_embedded esp32-ethernet-kit"
CACHE STRING
"List of components to include"
)

project(rtps_embedded_example)

set(CMAKE_CXX_STANDARD 20)
3 changes: 3 additions & 0 deletions components/rtps_embedded/example/main/CMakeLists.txt
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idf_component_register(SRC_DIRS "."
INCLUDE_DIRS "."
)
10 changes: 10 additions & 0 deletions components/rtps_embedded/example/main/Kconfig.projbuild
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menu "RTPS Example Configuration"

config RTPS_EXAMPLE_ANNOUNCE_PERIOD_MS
int "Publish period (ms)"
range 200 60000
default 1500
help
Period between outgoing messages published by the MCU.

endmenu
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