Merge remote-tracking branch 'Thecave3/e3-agent-framework' into integration_2026_w27

Implementation of the E3 Agent for dApps and E3AP (no service models) (#204) These changes introduce an E3 Agent for dApps in the OAI codebase. dApps are real-time microservices designed to operate within the O-RAN ecosystem, enabling sub-10 ms Artificial Intelligence (AI) routines in the Radio Access Network (RAN). The E3 Agent enables spectrum sensing, frequency-domain signal logging, and dynamic PRB (Physical Resource Block) policies through IPC/ZMQ communication with dApps or xApps. The dApps are designed for co-location with the CU/DU, where it can interact directly with user-plane data to enable different network management scenarios such as optimizing network slicing, scheduling, and resource management. A python library for the creation of the dApps is available here [1]. Additional information about dApps: - Paper on the dApp architecture [2] - dApp framework presentation [3] - Tutorial on dApp deployment on OAI [4] As agreed in the original MR [5], this PR includes only the agent lifecycle, configuration parsing, build plumbing, and the nr-softmodem init/destroy hook. It registers zero service models, so it builds and runs as an idle agent. Concrete service models (e.g. spectrum sensing) and the PHY/MAC hooks that drive them follow in later PRs. Opt-in and dependencies - Gated behind the E3_AGENT CMake option (OFF by default) / the --build-e3 build flag. The default build is unaffected — e3ap is only compiled and linked into nr-softmodem when E3_AGENT=ON. - When enabled, requires the external libe3 library [6] (vendor-neutral E3AP C++ lib), discovered via pkg_check_modules(CLIBE3 REQUIRED libe3). It is not vendored. Install libe3 (Debian/Ubuntu): git clone https://github.com/wineslab/libe3 && cd libe3 ./build_libe3 -I # installs deps: build-essential cmake pkg-config libzmq3-dev asn1c nlohmann-json3-dev libsctp-dev ... ./build_libe3 --install # release build + installation Build & test Tested in RFsim: the gNB initializes the E3 agent, opens its setup socket (/tmp/dapps/setup), registers zero service models, and runs without crashing. Configuration The agent reads an optional E3Configuration section from the gNB config file (parsed only when E3_AGENT=ON). If absent, it falls back to built-in defaults (posix/ipc). E3Configuration : { link = "zmq"; # posix | zmq transport = "ipc"; # tcp | sctp | ipc }; The same parameters can be overridden on the command line (no config-file edit required): sudo ./nr-softmodem -O <gnb.conf> ... --E3Configuration.link zmq --E3Configuration.transport ipc Validated link/transport combinations: (zmq,ipc) (zmq,tcp) (posix,tcp) (posix,sctp) (posix,ipc). Notes - I have added a new log component E3AP specific for the ops performed by the E3 Agent. - This PR ships no gNB config file; the E3Configuration block / CLI override above is the documented way to enable the agent. Example configs follow in the next PRs. [1] https://pypi.org/project/dapps/ [2] https://arxiv.org/pdf/2501.16502 [3] https://openrangym.com/o-ran-frameworks/dapps [4] https://openrangym.com/tutorials/dapps-oai [5] https://gitlab.eurecom.fr/oai/openairinterface5g/-/merge_requests/3361 [6] https://github.com/wineslab/libe3 Reviewed-by: Teodora Vladić <teodora.vladic@openairinterface.org> Reviewed-by: Sagar Arora <sagar.arora@openairinterface.org> Reviewed-by: Robert Schmidt <robert.schmidt@openairinterface.org>
2026-07-13 04:30:28 +00:00 · 2026-07-02 18:35:23 +02:00
parent 465b57d8c5 602d729d43
commit 69a017f57b
12 changed files with 599 additions and 0 deletions
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -383,6 +383,12 @@ endif()
 add_boolean_option(ENABLE_IMSCOPE OFF "Enable phy scope based on imgui" OFF)
 add_boolean_option(ENABLE_IMSCOPE_RECORD OFF "Enable recording IQ data for imscope" OFF)

+#########################
+##### E3 AGENT
+#########################
+set(E3_AGENT "OFF" CACHE STRING "O-RAN nGRG E3 Agent for dApps")
+set_property(CACHE E3_AGENT PROPERTY STRINGS "ON" "OFF")
+
 ##################################################
 # ASN.1 grammar C code generation & dependencies #
 ##################################################
@@ -1831,6 +1837,11 @@ if(E2_AGENT)
  target_compile_definitions(nr-softmodem PRIVATE ${E2AP_VERSION} ${KPM_VERSION} E2_AGENT)
 endif()

+if (E3_AGENT)
+    target_link_libraries(nr-softmodem PRIVATE e3ap)
+    target_compile_definitions(nr-softmodem PRIVATE E3_AGENT)
+endif()
+

 # force the generation of ASN.1 so that we don't need to wait during the build
 target_link_libraries(nr-softmodem PRIVATE
--- a/cmake_targets/build_oai
+++ b/cmake_targets/build_oai
@@ -43,6 +43,8 @@ Options:
   Sets build directory (will be <oai-root>/cmake_targets/<build-dir>/build)
 --build-e2
   Enable the the E2 Agent
+--build-e3
+   Enable the the E3 Agent
 -I | --install-external-packages
   Installs required packages such as LibXML, asn1.1 compiler, ...
   This option will require root password
@@ -143,6 +145,10 @@ function main() {
             CMAKE_CMD="$CMAKE_CMD -DE2_AGENT=ON"
             shift
             ;;
+       --build-e3 )
+             CMAKE_CMD="$CMAKE_CMD -DE3_AGENT=ON"
+             shift
+             ;;
       -I | --install-external-packages)
            INSTALL_EXTERNAL=1
            echo_info "Will install external packages"
--- a/common/utils/LOG/log.h
+++ b/common/utils/LOG/log.h
@@ -155,6 +155,7 @@ static const char *const flag_name[] = {FOREACH_FLAG(FLAG_TEXT) ""};
  COMP_DEF(NFAPI_PNF, log)      \
  COMP_DEF(ITTI, log)           \
  COMP_DEF(UTIL, log)           \
+  COMP_DEF(E3AP, log)           \
  COMP_DEF(MAX_LOG_PREDEF_COMPONENTS, )

 #define COMP_ENUM(comp, file_extension) comp,
--- a/common/utils/T/T_messages.txt
+++ b/common/utils/T/T_messages.txt
@@ -434,6 +434,27 @@ ID = LEGACY_MAC_TRACE
    GROUP = ALL:LEGACY_MAC:LEGACY_GROUP_TRACE:LEGACY
    FORMAT = string,log

+ID = LEGACY_E3AP_INFO
+     DESC = E3AP legacy logs - info level
+     GROUP = ALL:LEGACY_E3AP:LEGACY_GROUP_INFO:LEGACY
+     FORMAT = string,log
+ID = LEGACY_E3AP_ERROR
+    DESC = E3AP legacy logs - error level
+    GROUP = ALL:LEGACY_E3AP:LEGACY_GROUP_ERROR:LEGACY
+    FORMAT = string,log
+ID = LEGACY_E3AP_WARNING
+    DESC = E3AP legacy logs - warning level
+    GROUP = ALL:LEGACY_E3AP:LEGACY_GROUP_WARNING:LEGACY
+    FORMAT = string,log
+ID = LEGACY_E3AP_DEBUG
+     DESC = E3AP legacy logs - debug level
+     GROUP = ALL:LEGACY_E3AP:LEGACY_GROUP_DEBUG:LEGACY
+     FORMAT = string,log
+ID = LEGACY_E3AP_TRACE
+    DESC = E3AP legacy logs - trace level
+    GROUP = ALL:LEGACY_E3AP:LEGACY_GROUP_TRACE:LEGACY
+    FORMAT = string,log
+
 ID = LEGACY_NR_MAC_INFO
    DESC = NR_MAC legacy logs - info level
    GROUP = ALL:LEGACY_NR_MAC:LEGACY_GROUP_INFO:LEGACY
--- a/executables/nr-softmodem.c
+++ b/executables/nr-softmodem.c
@@ -19,6 +19,11 @@ unsigned short config_frames[4] = {2,9,11,13};
 #include "openair2/E2AP/flexric/src/agent/e2_agent_api.h"
 #include "openair2/E2AP/RAN_FUNCTION/init_ran_func.h"
 #endif
+
+#ifdef E3_AGENT
+#include "openair2/E3AP/e3_agent.h"
+#endif
+
 #include "nr-softmodem.h"
 #include <common/utils/assertions.h>
 #include <openair2/GNB_APP/gnb_app.h>
@@ -520,6 +525,13 @@ int main( int argc, char **argv ) {

  softmodem_verify_mode(get_softmodem_params());

+//////////////////////////////////
+//// Init the E3 Agent
+#ifdef E3_AGENT
+  printf("Init E3 Agent\n");
+  e3_init();
+#endif // E3_AGENT
+
 #if T_TRACER
  T_Config_Init();
 #endif
@@ -726,6 +738,11 @@ int main( int argc, char **argv ) {

  time_manager_finish();

+#ifdef E3_AGENT
+  printf("Destroy E3 Agent\n");
+  e3_destroy();
+#endif // E3_AGENT
+
  free(pckg);
  logClean();
  printf("Bye.\n");
--- a/openair2/CMakeLists.txt
+++ b/openair2/CMakeLists.txt
@@ -5,6 +5,10 @@ add_subdirectory(E1AP)
 if(E2_AGENT)
  add_subdirectory(E2AP)
 endif()
+if(E3_AGENT)
+  message(STATUS "Add E3 Agent capabilities")
+  add_subdirectory(E3AP)
+endif()
 add_subdirectory(F1AP)
 add_subdirectory(LAYER2)
 add_subdirectory(M2AP)
--- a/openair2/E3AP/CMakeLists.txt
+++ b/openair2/E3AP/CMakeLists.txt
@@ -0,0 +1,44 @@
+# SPDX-License-Identifier: LicenseRef-CSSL-1.0
+
+find_package(PkgConfig REQUIRED)
+pkg_check_modules(CLIBE3 REQUIRED libe3)
+
+if(NOT CLIBE3_FOUND)
+    message(FATAL_ERROR "libe3 not found and required for E3 Agent")
+endif()
+
+message(STATUS "Using for E3AP libe3 version: ${CLIBE3_VERSION}")
+
+include_directories(${CLIBE3_INCLUDE_DIRS})
+
+# Set default encoding format if not specified
+if(NOT DEFINED E3_ENCODING_FORMAT)
+    set(E3_ENCODING_FORMAT "ASN1" CACHE STRING "E3AP encoding format (ASN1 or JSON)")
+endif()
+
+# Validate encoding format
+if(NOT E3_ENCODING_FORMAT MATCHES "^(ASN1|JSON)$")
+    message(FATAL_ERROR "Invalid E3_ENCODING_FORMAT: ${E3_ENCODING_FORMAT}. Must be ASN1 or JSON")
+endif()
+
+message(STATUS "E3AP encoding format: ${E3_ENCODING_FORMAT}")
+
+add_library(e3ap e3_agent.c config/e3_config.c)
+
+# target_link_libraries(e3ap PUBLIC OCP_ITTI) # TODO
+
+# Set encoding format compile definitions - both string value and format flags
+target_compile_definitions(e3ap PRIVATE E3_ENCODING_FORMAT="${E3_ENCODING_FORMAT}")
+
+if(E3_ENCODING_FORMAT STREQUAL "ASN1")
+    target_compile_definitions(e3ap PRIVATE E3_ASN1_FORMAT)
+    target_link_libraries(e3ap PUBLIC ${CLIBE3_LIBRARIES})
+elseif(E3_ENCODING_FORMAT STREQUAL "JSON")
+    target_compile_definitions(e3ap PRIVATE E3_JSON_FORMAT)
+    pkg_check_modules(JSON_C REQUIRED json-c)
+    if(NOT JSON_C_FOUND)
+        message(FATAL_ERROR "JSON-C not found and required for JSON encoding, install it with apt-get install libjson-c-dev")
+    endif()
+    target_link_libraries(e3ap PUBLIC ${CLIBE3_LIBRARIES} ${JSON_C_LIBRARIES})
+    target_include_directories(e3ap PUBLIC ${JSON_C_INCLUDE_DIRS})
+endif()
--- a/openair2/E3AP/README.md
+++ b/openair2/E3AP/README.md
@@ -0,0 +1,118 @@
+<!-- SPDX-License-Identifier: CC-BY-4.0 -->
+
+# Overview
+
+This document describes the E3 Agent for dApps integrated in OAI gNB, and explains how to
+build, configure, and connect a dApp.
+
+[[_TOC_]]
+
+dApps can be real-time microservices co-located with the RAN node (DU or CU). Unlike xApps,
+which run on a nearRT-RIC and operate at 10 ms–1 s timescales, dApps execute directly on the
+RAN node and interact with user-plane data that is unavailable to RICs due to timing or
+privacy constraints. This enables sub-millisecond control loops for use cases such as spectrum
+sharing, positioning, and scheduling optimization.
+
+The E3 interface connects the gNB to co-located dApps. The `libe3` library implements both
+sides of this interface — the RAN agent (this module) and the dApp client — using a unified
+C++/Python API that hides transport, encoding, and protocol complexity.
+
+For a complete description of the dApp architecture and the E3 interface, refer to:
+
+- [Paper: dApp architecture and E3 interface (Computer Networks, 2025)](https://doi.org/10.1016/j.comnet.2025.111342)
+- [Tutorial: deploying dApps with OAI](https://openrangym.com/tutorials/dapps-oai)
+- [dApp Python library](https://pypi.org/project/dapps/)
+
+## 1. Prerequisites — libe3
+
+The E3 Agent requires the external `libe3` library, discovered at build time via
+`pkg_check_modules(CLIBE3 REQUIRED libe3)`. It is not vendored in OAI.
+
+```bash
+git clone https://github.com/wineslab/libe3 && cd libe3
+./build_libe3 -I       # install system prerequisites if not already present
+./build_libe3 --install
+```
+
+## 2. Build OAI with the E3 Agent
+
+The E3 Agent is **opt-in** and gated behind the `E3_AGENT` CMake option (`OFF` by default).
+The default OAI build is entirely unaffected when `E3_AGENT` is not set.
+
+```bash
+cd cmake_targets/
+./build_oai -w SIMU --ninja --gNB --nrUE --build-e3
+```
+
+To build without the E3 Agent, omit `--build-e3`. To clean and rebuild, add the `-c` flag.
+
+## 3. Configuration
+
+The agent reads an optional `E3Configuration` block from the gNB configuration file.
+If the block is absent, the agent falls back to built-in defaults (`posix`/`ipc`).
+
+```
+E3Configuration : {
+    link      = "zmq";   # posix | zmq
+    transport = "ipc";   # tcp | sctp | ipc
+};
+```
+
+The same parameters can be set on the command line without editing the config file:
+
+```bash
+sudo ./nr-softmodem -O <gnb.conf> ... --E3Configuration.link zmq --E3Configuration.transport ipc
+```
+
+Valid link/transport combinations:
+
+| link  | transport |
+|-------|-----------|
+| zmq   | ipc       |
+| zmq   | tcp       |
+| posix | ipc       |
+| posix | tcp       |
+| posix | sctp      |
+
+## 4. dApp development
+
+dApps are written in Python using the `dapps` library:
+
+```bash
+pip install "dapps[all]"
+```
+
+A dApp subclasses the `DApp` base class and implements service-model-specific encode/decode
+and a control loop. The library handles the E3 connection transparently: setup handshake,
+subscription, indication receive, and control send.
+
+At the current status, no service models have been included so far.
+
+For a full end-to-end example including service model usage, follow the
+[tutorial on the OpenRAN Gym website](https://openrangym.com/tutorials/dapps-oai).
+
+## 5. Start the process
+
+### 5.1 Start the gNB with E3 agent enabled
+
+The example below uses RFsim for local testing. A 5G Core Network must already be running;
+see [`doc/NR_SA_Tutorial_OAI_CN5G.md`](../../doc/NR_SA_Tutorial_OAI_CN5G.md).
+
+```bash
+cd cmake_targets/ran_build/build
+sudo ./nr-softmodem \
+  -O <path>/targets/PROJECTS/GENERIC-NR-5GC/CONF/gnb.sa.band78.fr1.106PRB.pci0.rfsim.conf \
+  --rfsim \
+  --E3Configuration.link zmq --E3Configuration.transport ipc
+```
+
+If the agent initializes correctly, the log will show `Init E3 Agent` and the setup socket
+will appear at `/tmp/dapps/setup`.
+
+An `E3AP` log component is available for debugging: pass `--log_config.e3ap_log_level debug`
+to increase verbosity.
+
+### 5.2 Connect a dApp
+
+Follow the [deployment tutorial](https://openrangym.com/tutorials/dapps-oai) for a complete
+end-to-end example.
--- a/openair2/E3AP/config/e3_config.c
+++ b/openair2/E3AP/config/e3_config.c
@@ -0,0 +1,73 @@
+/*
+ * SPDX-License-Identifier: LicenseRef-CSSL-1.0
+ */
+
+#include "e3_config.h"
+#include "common/utils/LOG/log.h"
+#include "common/config/config_paramdesc.h"
+#include "common/config/config_userapi.h"
+
+#define E3CONFIG_SECTION "E3Configuration"
+
+#define simOpt PARAMFLAG_NOFREE | PARAMFLAG_CMDLINE_NOPREFIXENABLED
+
+/* String-to-integer mappings for link, transport, and encoding.
+ * Values must match the libe3 e3_config_t enum ordering. */
+// clang-format off
+#define E3_LINK_OKSTRINGS      {"zmq",  "posix"}
+#define E3_LINK_VALUES         {E3_LINK_ZMQ, E3_LINK_POSIX}
+#define E3_TRANSPORT_OKSTRINGS {"sctp", "tcp", "ipc"}
+#define E3_TRANSPORT_VALUES    {E3_TRANSPORT_SCTP, E3_TRANSPORT_TCP, E3_TRANSPORT_IPC}
+#define E3_ENCODING_OKSTRINGS  {"asn1", "json"}
+#define E3_ENCODING_VALUES     {E3_ENCODING_ASN1, E3_ENCODING_JSON}
+
+#define E3_LINK_IDX      0
+#define E3_TRANSPORT_IDX 1
+#define E3_ENCODING_IDX  2
+// clang-format on
+
+void e3_readconfig(e3_cmdline_config_t *config)
+{
+  /* Temporary string storage for the string→int parameters. */
+  char *s_link = NULL, *s_transport = NULL, *s_encoding = NULL;
+
+  // clang-format off
+  paramdef_t e3_params[] = {
+    /* optname             helpstr                                   paramflags  value                           defval      type          numelt */
+    {"link",              "Link layer for E3 (zmq|posix)",           simOpt, .strptr  = &s_link,               .defstrval = "posix", TYPE_STRING,  0},
+    {"transport",         "Transport layer for E3 (sctp|tcp|ipc)",   simOpt, .strptr  = &s_transport,          .defstrval = "ipc",   TYPE_STRING,  0},
+    {"encoding",          "Encoding format for E3 (asn1|json)",      simOpt, .strptr  = &s_encoding,           .defstrval = "asn1",  TYPE_STRING,  0},
+    {"setup_port",        "E3 setup port (0=libe3 default)",         simOpt, .u16ptr  = &config->setup_port,      .defuintval = 0, TYPE_UINT16, 0},
+    {"subscriber_port",   "E3 subscriber port (0=libe3 default)",    simOpt, .u16ptr  = &config->subscriber_port, .defuintval = 0, TYPE_UINT16, 0},
+    {"publisher_port",    "E3 publisher port (0=libe3 default)",     simOpt, .u16ptr  = &config->publisher_port,  .defuintval = 0, TYPE_UINT16, 0},
+  };
+
+  checkedparam_t e3_checks[] = {
+    {.s3a = {config_checkstr_assign_integer, E3_LINK_OKSTRINGS,      E3_LINK_VALUES,      2}},
+    {.s3a = {config_checkstr_assign_integer, E3_TRANSPORT_OKSTRINGS, E3_TRANSPORT_VALUES, 3}},
+    {.s3a = {config_checkstr_assign_integer, E3_ENCODING_OKSTRINGS,  E3_ENCODING_VALUES,  2}},
+    {.s5 = {NULL}},
+    {.s5 = {NULL}},
+    {.s5 = {NULL}},
+  };
+  // clang-format on
+
+  config_set_checkfunctions(e3_params, e3_checks, sizeofArray(e3_params));
+
+  int ret = config_get(config_get_if(), e3_params, sizeofArray(e3_params), E3CONFIG_SECTION);
+  AssertFatal(ret >= 0, "E3Configuration: config_get failed\n");
+
+  config->link_layer = config_get_processedint(config_get_if(), &e3_params[E3_LINK_IDX]);
+  config->transport_layer = config_get_processedint(config_get_if(), &e3_params[E3_TRANSPORT_IDX]);
+  config->encoding = config_get_processedint(config_get_if(), &e3_params[E3_ENCODING_IDX]);
+  /* setup_port, subscriber_port, publisher_port written directly by config_get via u16ptr */
+
+  LOG_I(E3AP,
+        "E3 configuration: link=%d transport=%d encoding=%d setup_port=%u subscriber_port=%u publisher_port=%u\n",
+        config->link_layer,
+        config->transport_layer,
+        config->encoding,
+        config->setup_port,
+        config->subscriber_port,
+        config->publisher_port);
+}
--- a/openair2/E3AP/config/e3_config.h
+++ b/openair2/E3AP/config/e3_config.h
@@ -0,0 +1,38 @@
+/*
+ * SPDX-License-Identifier: LicenseRef-CSSL-1.0
+ */
+
+#ifndef E3_CONFIG_H
+#define E3_CONFIG_H
+
+#include <stdint.h>
+
+/* link_layer values (match libe3 e3_config_t; -1 = libe3 default) */
+#define E3_LINK_ZMQ 0
+#define E3_LINK_POSIX 1
+
+/* transport_layer values (match libe3 e3_config_t; -1 = libe3 default) */
+#define E3_TRANSPORT_SCTP 0
+#define E3_TRANSPORT_TCP 1
+#define E3_TRANSPORT_IPC 2
+
+/* encoding values (match libe3 e3_config_t; -1 = libe3 default) */
+#define E3_ENCODING_ASN1 0
+#define E3_ENCODING_JSON 1
+
+typedef struct {
+  int link_layer; /* E3_LINK_{ZMQ,POSIX}; -1 = libe3 default */
+  int transport_layer; /* E3_TRANSPORT_{SCTP,TCP,IPC}; -1 = libe3 default */
+  int encoding; /* E3_ENCODING_{ASN1,JSON}; -1 = libe3 default */
+  uint16_t setup_port; /* 0 = libe3 default (9990) */
+  uint16_t subscriber_port; /* 0 = libe3 default */
+  uint16_t publisher_port; /* 0 = libe3 default */
+} e3_cmdline_config_t;
+
+/**
+ * @brief Read E3 configuration from the OAI config file
+ * @param config Pointer to configuration structure to fill
+ */
+void e3_readconfig(e3_cmdline_config_t *config);
+
+#endif // E3_CONFIG_H
--- a/openair2/E3AP/e3_agent.c
+++ b/openair2/E3AP/e3_agent.c
@@ -0,0 +1,206 @@
+/*
+ * SPDX-License-Identifier: LicenseRef-CSSL-1.0
+ */
+
+#include "e3_agent.h"
+#include "config/e3_config.h"
+
+// TODO replace pthreads with itti or use a faster way
+// #include "intertask_interface.h"
+// #include "create_tasks.h"
+#include <pthread.h>
+#include <errno.h>
+#include <time.h>
+
+#include <libe3/c_api.h>
+
+#include "common/utils/system.h"
+#include "common/ran_context.h"
+#include "common/utils/LOG/log.h"
+#include "openair2/GNB_APP/gnb_paramdef.h"
+
+e3_agent_global_t e3 = {0};
+
+static void e2_e3_bridge(uint32_t dapp_id, uint32_t ran_function_id, const uint8_t *report_data, size_t report_size)
+{
+  LOG_D(E3AP, "Received dApp report for RAN function %u from dApp %u (%zu bytes)\n", ran_function_id, dapp_id, report_size);
+#ifdef E2_AGENT
+  if (!report_data && report_size > 0) {
+    LOG_E(E3AP, "Invalid dApp report payload: report_data is NULL while report_size=%zu\n", report_size);
+    return;
+  }
+  generate_e2_indication_from_e3_dapp_report(ran_function_id, dapp_id, report_size, report_data);
+#else
+  (void)report_data;
+#endif
+}
+
+void on_dapp_status_changed(void)
+{
+  LOG_I(E3AP, "dApp status changed, triggering RIC Service Update\n");
+#ifdef E2_AGENT
+  notify_dapp_status_changed();
+#endif
+}
+
+int e3_init()
+{
+  LOG_D(E3AP, "Read configuration\n");
+  e3_cmdline_config_t *e3_cmdline_configs = (e3_cmdline_config_t *)calloc(1, sizeof(e3_cmdline_config_t));
+  if (!e3_cmdline_configs) {
+    LOG_E(E3AP, "Failed to allocate E3 cmdline config\n");
+    return -1;
+  }
+  e3_readconfig(e3_cmdline_configs);
+
+  /* Read gNB name to use as E3 agent identifier */
+  char *gnb_name = NULL;
+  paramdef_t name_param[] = {{GNB_CONFIG_STRING_GNB_NAME, NULL, 0, .strptr = &gnb_name, .defstrval = "OAI gNB", TYPE_STRING, 0}};
+  config_get(config_get_if(), name_param, 1, GNB_CONFIG_STRING_GNB_LIST ".[0]");
+
+  e3_config_t config = {0};
+  config.ran_identifier = gnb_name ? gnb_name : "OAI gNB";
+  config.log_level = g_log->log_component[E3AP].level;
+  config.link_layer = e3_cmdline_configs->link_layer;
+  config.transport_layer = e3_cmdline_configs->transport_layer;
+  config.encoding = e3_cmdline_configs->encoding;
+  config.setup_port = e3_cmdline_configs->setup_port;
+  config.subscriber_port = e3_cmdline_configs->subscriber_port;
+  config.publisher_port = e3_cmdline_configs->publisher_port;
+
+  e3.agent = e3_agent_create_with_config(&config);
+  free(e3_cmdline_configs);
+  e3_cmdline_configs = NULL;
+  if (!e3.agent) {
+    LOG_E(E3AP, "Failed to create E3Agent with config\n");
+    return -1;
+  }
+
+  // Initialize agent
+  e3_error_t err = e3_agent_init(e3.agent);
+  if (err != 0) {
+    LOG_E(E3AP, "Failed to initialize E3Agent (err=%d)\n", err);
+    e3_agent_destroy(e3.agent);
+    e3.agent = NULL;
+    return -1;
+  }
+
+  // Start agent
+  err = e3_agent_start(e3.agent);
+  if (err != 0) {
+    LOG_E(E3AP, "Failed to start E3Agent (err=%d)\n", err);
+    e3_agent_destroy(e3.agent);
+    e3.agent = NULL;
+    return -1;
+  }
+
+  err = e3_agent_set_dapp_report_handler(e3.agent, e2_e3_bridge);
+  if (err != 0) {
+    LOG_E(E3AP, "Failed to set dApp report handler (err=%d: %s)\n", err, e3_error_to_string(err));
+    e3_agent_destroy(e3.agent);
+    e3.agent = NULL;
+    return -1;
+  }
+
+  err = e3_agent_set_dapp_status_changed_handler(e3.agent, on_dapp_status_changed);
+  if (err != 0) {
+    LOG_E(E3AP, "Failed to set dApp status changed handler (err=%d: %s)\n", err, e3_error_to_string(err));
+    e3_agent_destroy(e3.agent);
+    e3.agent = NULL;
+    return -1;
+  }
+
+  // No concrete service models are registered by the framework itself; service
+  // models (e.g. spectrum sensing) register themselves in their own modules.
+  return 0;
+}
+
+int e3_destroy()
+{
+  // Stop and destroy the E3Agent if it exists
+  if (e3.agent) {
+    e3_agent_stop(e3.agent);
+    e3_agent_destroy(e3.agent);
+    e3.agent = NULL;
+  }
+
+  return 0;
+}
+
+int e3_send_xapp_control(uint32_t dapp_id, uint32_t ran_function_id, const uint8_t *data, size_t len)
+{
+  if (!e3.agent) {
+    LOG_E(E3AP, "E3 agent not initialized: cannot send xApp control\n");
+    return -1;
+  }
+
+  if (data == NULL && len > 0) {
+    LOG_E(E3AP, "data is not initialized, but len > 0\n");
+    return -1;
+  }
+
+  e3_error_t err = e3_agent_send_xapp_control(e3.agent, dapp_id, ran_function_id, data, len);
+  if (err != E3_SUCCESS) {
+    LOG_E(E3AP, "Failed to send xApp control to dApp %u for RAN function %u (err=%d)\n", dapp_id, ran_function_id, err);
+    return -1;
+  }
+  return 0;
+}
+
+e3_dapp_subscription_map_t e3_get_dapp_subscription_map(void)
+{
+  e3_dapp_subscription_map_t map = {0};
+
+  if (!e3.agent) {
+    LOG_W(E3AP, "E3 agent not initialized: cannot query dApp subscriptions\n");
+    return map;
+  }
+
+  size_t num_dapps = 0;
+  uint32_t *dapp_ids = e3_agent_get_registered_dapps(e3.agent, &num_dapps);
+  if (!dapp_ids || num_dapps == 0) {
+    e3_agent_free_uint32_array(dapp_ids);
+    return map;
+  }
+
+  map.dapps = calloc(num_dapps, sizeof(e3_dapp_info_t));
+  if (!map.dapps) {
+    LOG_E(E3AP, "Failed to allocate dApp subscription map\n");
+    e3_agent_free_uint32_array(dapp_ids);
+    return map;
+  }
+  map.num_dapps = num_dapps;
+
+  for (size_t i = 0; i < num_dapps; i++) {
+    map.dapps[i].dapp_id = dapp_ids[i];
+
+    size_t num_subs = 0;
+    uint32_t *subs = e3_agent_get_dapp_subscriptions(e3.agent, dapp_ids[i], &num_subs);
+
+    if (subs && num_subs > 0) {
+      map.dapps[i].e3_ran_func_ids = subs; // transfer ownership from libe3 malloc
+      map.dapps[i].num_e3_ran_funcs = num_subs;
+    } else {
+      map.dapps[i].e3_ran_func_ids = NULL;
+      map.dapps[i].num_e3_ran_funcs = 0;
+      e3_agent_free_uint32_array(subs);
+    }
+  }
+
+  e3_agent_free_uint32_array(dapp_ids);
+  return map;
+}
+
+void e3_free_dapp_subscription_map(e3_dapp_subscription_map_t *map)
+{
+  if (!map || !map->dapps)
+    return;
+
+  for (size_t i = 0; i < map->num_dapps; i++) {
+    e3_agent_free_uint32_array(map->dapps[i].e3_ran_func_ids);
+  }
+  free(map->dapps);
+
+  map->dapps = NULL;
+  map->num_dapps = 0;
+}
--- a/openair2/E3AP/e3_agent.h
+++ b/openair2/E3AP/e3_agent.h
@@ -0,0 +1,60 @@
+/*
+ * SPDX-License-Identifier: LicenseRef-CSSL-1.0
+ */
+
+#ifndef E3_AGENT_H
+#define E3_AGENT_H
+
+#include <stdlib.h>
+#include <string.h>
+#include <pthread.h>
+
+#include <unistd.h>
+
+#include <libe3/c_api.h>
+
+#include "config/e3_config.h"
+
+#ifdef E2_AGENT
+#include "ran_func_dapp_extern.h"
+#endif
+
+typedef struct {
+  e3_agent_handle_t *agent;
+  e3_service_model_handle_t **service_models;
+  size_t num_service_models;
+} e3_agent_global_t;
+
+typedef struct {
+  uint32_t dapp_id;
+  uint32_t *e3_ran_func_ids;
+  size_t num_e3_ran_funcs;
+} e3_dapp_info_t;
+
+typedef struct {
+  e3_dapp_info_t *dapps;
+  size_t num_dapps;
+} e3_dapp_subscription_map_t;
+
+extern e3_agent_global_t e3;
+
+int e3_init();
+int e3_destroy();
+
+int e3_send_xapp_control(uint32_t dapp_id, uint32_t ran_function_id, const uint8_t *data, size_t len);
+
+/**
+ * @brief Get all connected dApps and their RAN function subscriptions.
+ *
+ * Caller must free the result with e3_free_dapp_subscription_map().
+ *
+ * @return populated map on success, {NULL, 0} on error or if no dApps
+ */
+e3_dapp_subscription_map_t e3_get_dapp_subscription_map(void);
+
+/**
+ * @brief Free a subscription map returned by e3_get_dapp_subscription_map().
+ */
+void e3_free_dapp_subscription_map(e3_dapp_subscription_map_t *map);
+
+#endif // E3_AGENT_H