Python Bindings for Publisher, Subscriber and Service Request features.

.gitignore

@@ -5,3 +5,6 @@ build_*
 # OS generated files
 .DS_Store
 *.swp
+
+# Python generated files
+*.pyc

CMakeLists.txt

@@ -15,10 +15,25 @@ set(GZ_CMAKE_VER ${gz-cmake3_VERSION_MAJOR})
 #============================================================================
 # Configure the project
 #============================================================================
+option(SKIP_PYBIND11
+      "Skip generating Python bindings via pybind11"
+      OFF)
+
+# Python interfaces vars
+include(CMakeDependentOption)
+include(GzPython)
+cmake_dependent_option(USE_SYSTEM_PATHS_FOR_PYTHON_INSTALLATION
+      "Install python modules in standard system paths in the system"
+      OFF "NOT SKIP_PYBIND11" OFF)
+
+cmake_dependent_option(USE_DIST_PACKAGES_FOR_PYTHON
+      "Use dist-packages instead of site-package to install python modules"
+      OFF "NOT SKIP_PYBIND11" OFF)
+
 set(CMAKE_CXX_STANDARD 17)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 
-gz_configure_project(VERSION_SUFFIX pre1)
+gz_configure_project(VERSION_SUFFIX)
 
 #============================================================================
 # Set project-specific options
@@ -117,14 +132,45 @@ gz_find_package(SQLite3
 #============================================================================
 # Configure the build
 #============================================================================
+
+########################################
+# Python interfaces
+if (NOT PYTHON3_FOUND)
+  GZ_BUILD_WARNING("Python is missing: Python interfaces are disabled.")
+  message (STATUS "Searching for Python - not found.")
+else()
+  message (STATUS "Searching for Python - found version ${Python3_VERSION}.")
+
+  if (SKIP_PYBIND11)
+    message(STATUS "SKIP_PYBIND11 set - disabling python bindings")
+  else()
+    set(PYBIND11_PYTHON_VERSION 3)
+    find_package(pybind11 2.4 QUIET)
+
+    if (${pybind11_FOUND})
+      find_package(Python3 ${GZ_PYTHON_VERSION} REQUIRED COMPONENTS Development)
+      message (STATUS "Searching for pybind11 - found version ${pybind11_VERSION}.")
+    else()
+      GZ_BUILD_WARNING("pybind11 is missing: Python interfaces are disabled.")
+      message (STATUS "Searching for pybind11 - not found.")
+    endif()
+  endif()
+endif()
+
 gz_configure_build(QUIT_IF_BUILD_ERRORS
   COMPONENTS log parameters)
-
 #============================================================================
 # gz command line support
 #============================================================================
 add_subdirectory(conf)
 
+#============================================================================
+# gz transport python bindings
+#============================================================================
+if (pybind11_FOUND AND NOT SKIP_PYBIND11)
+  add_subdirectory(python)
+endif()
+
 #============================================================================
 # Create package information
 #============================================================================

python/CMakeLists.txt

@@ -0,0 +1,98 @@
+if(WIN32 AND CMAKE_BUILD_TYPE STREQUAL "Debug")
+  # pybind11 logic for setting up a debug build when both a debug and release
+  # python interpreter are present in the system seems to be pretty much broken.
+  # This works around the issue.
+  set(PYTHON_LIBRARIES "${PYTHON_DEBUG_LIBRARIES}")
+endif()
+
+if(USE_SYSTEM_PATHS_FOR_PYTHON_INSTALLATION)
+  if(${CMAKE_VERSION} VERSION_LESS "3.12.0")
+    execute_process(
+      COMMAND "${PYTHON_EXECUTABLE}" -c "if True:
+  from distutils import sysconfig as sc
+  print(sc.get_python_lib(plat_specific=True))"
+      OUTPUT_VARIABLE Python3_SITEARCH
+      OUTPUT_STRIP_TRAILING_WHITESPACE)
+  else()
+    # Get install variable from Python3 module
+    # Python3_SITEARCH is available from 3.12 on, workaround if needed:
+    find_package(Python3 COMPONENTS Interpreter)
+  endif()
+
+  if(USE_DIST_PACKAGES_FOR_PYTHON)
+    string(REPLACE "site-packages" "dist-packages" GZ_PYTHON_INSTALL_PATH ${Python3_SITEARCH})
+  else()
+    # custom cmake command is returning dist-packages
+    string(REPLACE "dist-packages" "site-packages" GZ_PYTHON_INSTALL_PATH ${Python3_SITEARCH})
+  endif()
+else()
+  # If not a system installation, respect local paths
+  set(GZ_PYTHON_INSTALL_PATH ${GZ_LIB_INSTALL_DIR}/python/gz)
+endif()
+
+# Set the build location and install location for a CPython extension
+function(configure_build_install_location _library_name)
+  # Install library for actual use
+  install(TARGETS ${_library_name}
+    DESTINATION "${GZ_PYTHON_INSTALL_PATH}/transport${PROJECT_VERSION_MAJOR}"
+  )
+endfunction()
+
+message(STATUS "Building pybind11 interfaces")
+set(BINDINGS_MODULE_NAME "_transport")
+# Split from main extension and converted to pybind11
+pybind11_add_module(${BINDINGS_MODULE_NAME} MODULE
+  src/transport/_gz_transport_pybind11.cc
+)
+
+target_link_libraries(${BINDINGS_MODULE_NAME} PRIVATE
+  ${PROJECT_LIBRARY_TARGET_NAME}
+)
+
+target_compile_definitions(${BINDINGS_MODULE_NAME} PRIVATE
+  BINDINGS_MODULE_NAME=${BINDINGS_MODULE_NAME})
+
+# Deal with naming collision on Windows. It is caused by the both the import
+# library of sdformat library and the import library of the pybind11 bindings
+# library are called sdformat13.lib.
+set_target_properties(${BINDINGS_MODULE_NAME} PROPERTIES
+  ARCHIVE_OUTPUT_NAME "python_transport${PROJECT_VERSION_MAJOR}")
+
+configure_build_install_location(${BINDINGS_MODULE_NAME})
+
+install(FILES
+  src/__init__.py  
+  DESTINATION "${GZ_PYTHON_INSTALL_PATH}/transport${PROJECT_VERSION_MAJOR}"
+)
+
+if (BUILD_TESTING AND NOT WIN32)
+
+  set(python_tests
+    pubSub_TEST
+  )
+  execute_process(COMMAND "${Python3_EXECUTABLE}" -m pytest --version
+    OUTPUT_VARIABLE PYTEST_output
+    ERROR_VARIABLE  PYTEST_error
+    RESULT_VARIABLE PYTEST_result)
+  if(${PYTEST_result} EQUAL 0)
+    set(pytest_FOUND TRUE)
+  else()
+    message("")
+    message(WARNING "Pytest package not available: ${PYTEST_error}")
+  endif()
+
+  foreach (test ${python_tests})
+    if (pytest_FOUND)
+      add_test(NAME ${test}.py COMMAND
+        "${Python3_EXECUTABLE}" -m pytest "${CMAKE_SOURCE_DIR}/python/test/${test}.py" --junitxml "${CMAKE_BINARY_DIR}/test_results/${test}.xml")
+    else()
+      add_test(NAME ${test}.py COMMAND
+        "${Python3_EXECUTABLE}" "${CMAKE_SOURCE_DIR}/python/test/${test}.py")
+    endif()
+    set(_env_vars)
+    list(APPEND _env_vars "PYTHONPATH=${CMAKE_INSTALL_PREFIX}/${CMAKE_INSTALL_LIBDIR}/python/:${CMAKE_BINARY_DIR}/lib:$ENV{PYTHONPATH}")
+    list(APPEND _env_vars "LD_LIBRARY_PATH=${CMAKE_INSTALL_PREFIX}/${CMAKE_INSTALL_LIBDIR}:$ENV{LD_LIBRARY_PATH}")
+    set_tests_properties(${test}.py PROPERTIES
+      ENVIRONMENT "${_env_vars}")
+  endforeach()
+endif()

python/examples/publisher.py

@@ -0,0 +1,42 @@
+from gz.msgs10.stringmsg_pb2 import StringMsg
+from gz.msgs10.vector3d_pb2 import Vector3d
+from gz.transport13 import AdvertiseMessageOptions
+from gz.transport13 import Node
+
+import time
+
+def main():
+    node = Node()
+    stringmsg_topic = "/example_stringmsg_topic"
+    vector3d_topic = "/example_vector3d_topic"
+    pub_stringmsg = node.advertise(stringmsg_topic, StringMsg)
+    pub_vector3d = node.advertise(vector3d_topic, Vector3d)
+
+    vector3d_msg = Vector3d()
+    vector3d_msg.x = 10
+    vector3d_msg.y = 15
+    vector3d_msg.z = 20
+
+    stringmsg_msg = StringMsg()
+    stringmsg_msg.data = "Hello" 
+    try:
+        count = 0
+        while True:
+          count += 1
+          vector3d_msg.x = count
+          #  if not pub_stringmsg.publish(stringmsg_msg) or not pub_vector3d.publish(vector3d_msg):
+          if not pub_vector3d.publish(vector3d_msg):
+              break
+              #  break
+
+          #  print("Publishing 'Hello' on topic [{}]".format(stringmsg_topic))
+          #  print("Publishing a Vector3d on topic [{}]".format(vector3d_topic))
+          print(vector3d_msg)
+          time.sleep(0.00001)
+
+    except KeyboardInterrupt:
+        pass
+
+
+if __name__ == "__main__":
+    main()

python/examples/requester.py

@@ -0,0 +1,16 @@
+from gz.msgs10.stringmsg_pb2 import StringMsg
+from gz.transport13 import Node
+
+def main():
+    node = Node()
+    service_name = "/echo"
+    request = StringMsg()
+    request.data = "Hello world"
+    response = StringMsg()
+    timeout = 5000
+
+    result, response = node.request(service_name, request, StringMsg, StringMsg, timeout, response)
+    print("Result:", result, "\nResponse:", response.data)
+
+if __name__ == "__main__":
+    main()

python/examples/subscriber.py

@@ -0,0 +1,49 @@
+from gz.msgs10.stringmsg_pb2 import StringMsg
+from gz.msgs10.vector3d_pb2 import Vector3d
+from gz.transport13 import SubscribeOptions
+from gz.transport13 import Node
+
+import time
+
+def stringmsg_cb(msg: StringMsg):
+    print("Received StringMsg: [{}]".format(msg.data))
+
+def vector3_cb(msg: Vector3d):
+    print("Received Vector3: [x: {}, y: {}, z: {}]".format(msg.x, msg.y, msg.z))
+
+def main():
+    # create a transport node
+    node = Node()
+    topic_stringmsg = "/example_stringmsg_topic"
+    topic_vector3d = "/example_vector3d_topic"
+
+    # subscribe to a topic by registering a callback
+    if node.subscribe(StringMsg, topic_stringmsg, stringmsg_cb):
+        print("Subscribing to type {} on topic [{}]".format(
+            StringMsg, topic_stringmsg))
+    else:
+        print("Error subscribing to topic [{}]".format(topic_stringmsg))
+        return
+
+    # subscribe to a topic by registering a callback
+    if node.subscribe(Vector3d, topic_vector3d, vector3_cb):
+        print("Subscribing to type {} on topic [{}]".format(
+            Vector3d, topic_vector3d))
+    else:
+        print("Error subscribing to topic [{}]".format(topic_vector3d))
+        return
+
+    # wait for shutdown
+    try:
+      while True:
+        time.sleep(0.001)
+    except KeyboardInterrupt:
+      pass
+    # TODO(azeey) The subscriber if we quit without unsubscribing. This may not
+    # be needed after https://github.com/gazebosim/gz-transport/pull/381.
+    node.unsubscribe(topic_stringmsg)
+    node.unsubscribe(topic_vector3d)
+    print("Done")
+
+if __name__ == "__main__":
+    main()

python/src/__init__.py

@@ -0,0 +1,35 @@
+from ._transport import Node as _Node
+from ._transport import AdvertiseMessageOptions, SubscribeOptions
+from importlib import import_module
+
+
+class Publisher(_Node.Publisher):
+
+    def publish(self, proto_msg):
+        msg_string = proto_msg.SerializeToString()
+        msg_type = proto_msg.DESCRIPTOR.full_name
+        return self.publish_raw(msg_string, msg_type)
+
+class Node(_Node):
+
+    def advertise(self, topic, msg_type, options=AdvertiseMessageOptions()):
+        return Publisher(
+            _Node.advertise(self, topic, msg_type.DESCRIPTOR.full_name,
+                            options))
+
+    def subscribe(self, msg_type, topic, callback, options=SubscribeOptions()):
+
+        def cb_deserialize(proto_msg, msg_size, msg_info):
+            deserialized_msg = msg_type()
+            deserialized_msg.ParseFromString(proto_msg)
+            callback(deserialized_msg)
+
+        return self.subscribe_raw(topic, cb_deserialize,
+                                  msg_type.DESCRIPTOR.full_name, options)
+
+    def request(self, service, request, request_type, response_type, timeout, response):
+        result, serialized_response = self.request_raw(service, request.SerializeToString(), request_type.DESCRIPTOR.full_name,
+                                response_type.DESCRIPTOR.full_name, timeout, response.SerializeToString())
+        deserialized_response = response_type()
+        deserialized_response.ParseFromString(serialized_response)
+        return result, deserialized_response