From 5d4a8a69accc29071eb7cb19aa00169d40a5ad0b Mon Sep 17 00:00:00 2001
From: CY Chen <cyc@nvidia.com>
Date: Fri, 5 Jun 2026 18:35:03 +0000
Subject: [PATCH 1/2] Expose rosidl buffer backend metadata in
 TopicEndpointInfo

Signed-off-by: CY Chen <cyc@nvidia.com>
---
 .../node_interfaces/node_graph_interface.hpp  | 21 +++++++++++++++++++
 .../src/rclcpp/node_interfaces/node_graph.cpp | 12 +++++++++++
 2 files changed, 33 insertions(+)

diff --git a/rclcpp/include/rclcpp/node_interfaces/node_graph_interface.hpp b/rclcpp/include/rclcpp/node_interfaces/node_graph_interface.hpp
index a548579585..397e721447 100644
--- a/rclcpp/include/rclcpp/node_interfaces/node_graph_interface.hpp
+++ b/rclcpp/include/rclcpp/node_interfaces/node_graph_interface.hpp
@@ -69,6 +69,16 @@ class TopicEndpointInfo
     topic_type_ = info.topic_type;
 
     std::copy(info.endpoint_gid, info.endpoint_gid + RMW_GID_STORAGE_SIZE, endpoint_gid_.begin());
+
+    const char * current_key = rcutils_string_map_get_next_key(
+      &info.buffer_backend_metadata, nullptr);
+    while (current_key) {
+      const char * current_value = rcutils_string_map_get(
+        &info.buffer_backend_metadata, current_key);
+      buffer_backend_metadata_[current_key] = current_value ? current_value : "";
+      current_key = rcutils_string_map_get_next_key(
+        &info.buffer_backend_metadata, current_key);
+    }
   }
 
   /// Get a mutable reference to the node name.
@@ -141,6 +151,16 @@ class TopicEndpointInfo
   const rosidl_type_hash_t &
   topic_type_hash() const;
 
+  /// Get a mutable reference to the buffer backend metadata.
+  RCLCPP_PUBLIC
+  std::map<std::string, std::string> &
+  buffer_backend_metadata();
+
+  /// Get a const reference to the buffer backend metadata.
+  RCLCPP_PUBLIC
+  const std::map<std::string, std::string> &
+  buffer_backend_metadata() const;
+
 private:
   std::string node_name_;
   std::string node_namespace_;
@@ -149,6 +169,7 @@ class TopicEndpointInfo
   std::array<uint8_t, RMW_GID_STORAGE_SIZE> endpoint_gid_;
   rclcpp::QoS qos_profile_;
   rosidl_type_hash_t topic_type_hash_;
+  std::map<std::string, std::string> buffer_backend_metadata_;
 };
 
 /**
diff --git a/rclcpp/src/rclcpp/node_interfaces/node_graph.cpp b/rclcpp/src/rclcpp/node_interfaces/node_graph.cpp
index a7b28733d2..749758241a 100644
--- a/rclcpp/src/rclcpp/node_interfaces/node_graph.cpp
+++ b/rclcpp/src/rclcpp/node_interfaces/node_graph.cpp
@@ -956,6 +956,18 @@ rclcpp::TopicEndpointInfo::topic_type_hash() const
   return topic_type_hash_;
 }
 
+std::map<std::string, std::string> &
+rclcpp::TopicEndpointInfo::buffer_backend_metadata()
+{
+  return buffer_backend_metadata_;
+}
+
+const std::map<std::string, std::string> &
+rclcpp::TopicEndpointInfo::buffer_backend_metadata() const
+{
+  return buffer_backend_metadata_;
+}
+
 std::string &
 rclcpp::ServiceEndpointInfo::node_name()
 {

From d269f4e36907d9f83da63ff5783c8dd3c81881d6 Mon Sep 17 00:00:00 2001
From: CY Chen <cyc@nvidia.com>
Date: Wed, 1 Jul 2026 13:58:32 +0000
Subject: [PATCH 2/2] Parse serialized buffer metadata in topic endpoint info

Signed-off-by: CY Chen <cyc@nvidia.com>
---
 .../rclcpp/node_interfaces/node_graph_interface.hpp | 13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

diff --git a/rclcpp/include/rclcpp/node_interfaces/node_graph_interface.hpp b/rclcpp/include/rclcpp/node_interfaces/node_graph_interface.hpp
index 397e721447..c1fe5d71c5 100644
--- a/rclcpp/include/rclcpp/node_interfaces/node_graph_interface.hpp
+++ b/rclcpp/include/rclcpp/node_interfaces/node_graph_interface.hpp
@@ -29,6 +29,8 @@
 #include "rcl/graph.h"
 #include "rcl/guard_condition.h"
 
+#include "rmw/impl/cpp/buffer_backend_metadata.hpp"
+
 #include "rclcpp/event.hpp"
 #include "rclcpp/macros.hpp"
 #include "rclcpp/node_interfaces/detail/node_interfaces_helpers.hpp"
@@ -70,15 +72,8 @@ class TopicEndpointInfo
 
     std::copy(info.endpoint_gid, info.endpoint_gid + RMW_GID_STORAGE_SIZE, endpoint_gid_.begin());
 
-    const char * current_key = rcutils_string_map_get_next_key(
-      &info.buffer_backend_metadata, nullptr);
-    while (current_key) {
-      const char * current_value = rcutils_string_map_get(
-        &info.buffer_backend_metadata, current_key);
-      buffer_backend_metadata_[current_key] = current_value ? current_value : "";
-      current_key = rcutils_string_map_get_next_key(
-        &info.buffer_backend_metadata, current_key);
-    }
+    buffer_backend_metadata_ =
+      rmw::impl::cpp::parse_buffer_backend_metadata(info.buffer_backend_metadata);
   }
 
   /// Get a mutable reference to the node name.