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Open Source C++ OPC-UA Server and Client Library

Build Status

LGPL OPC-UA server and client library written in C++ and with a lot of code auto-generated from xml specification using python.

Python bindings can be found in the python directory.

mailing list:!forum/freeopcua

Currently supported:

  • read, write, browse
  • translateBrowsePathToNodeId
  • DataChange Events
  • Events
  • Subscriptions
  • complete opc-ua address space generated from xml specification
  • Method call from client
  • Linux and Windows(VS13) support

Work in progress

  • StatusChange Events
  • Filtering
  • Documentation
  • Automatic generation of binary protocol from OPC schema files
    • Methods on server side

Not implemented yet (patches are welcome)

  • History
  • Security: Authentication, Certificates handling, ..


Documentation is sparse but several examples are availables:

C++ examples in
Python examples in can also be a usefull source of information

Example minimal client in python

  client = opcua.Client(False)

  objects = client.get_objects_node()
  print("Children of objects are: ", objects.get_children())

  var = objects.get_child(["3:AnObject", "AVariable"])
  print("Value of variable is: ", var.get_value())

Tested clients and servers with default settings

  • uaexperts client application
  • node-opcua (client and server tested)
  • ignition server
  • Beckhoff PLC (seems to be some issues, but mostly working)
  • ignition open-source sdk (server tested)
  • quickopc client sdk
  • prosysopc demo client
  • prosysopc demo server
  • unified automation sdk (client and server tested)


An environment supporting c++11 is necessary: gcc-4.8+, clang 3.4 or VS2013

Ubuntu (Debians)

There is a script debian.soft in the root for installing all required soft to build all repositories.

Using GNU autotools

autoreconf -f -i
./configure --prefix=/path/to/server
make check
make install
cd /path/to/server
LD_LIBRARY_PATH=./lib ./bin/opcuaserver

Using cmake


mkdir build
cd build
cmake ..
make test


Boost and libxml2 are necessary

rem compiling
mkdir build
cd build
cmake .. -DBOOST_ROOT=c:\boost_1_56
cmake --build
ctest -C Debug
cd bin\Debug


docker build .


C++ style

  • 2 spaces not tab
  • CamelCase
  • Local variables start with small letter
  • Global/member variables starts with capital letters
  • Use provided automatic formatter (Artistic Style) by invoking ./restyle

python code and API should follows PEP8 (many places should be fixed)

Address space and most protocol code are auto-generated and should not be modified directly. Every auto-generated file starts with a mention that it should not be edited. There's a lot of old hand written protocol code left that should use the auto-generated code. This is done by uncommenting struct names in schemas/ and removing old code and files in src/protocol and include/opc/ua/protocol/