index.rst 4.8 KB

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108
  1. Introduction
  2. ============
  3. open62541 (http://open62541.org) is an open source and free implementation of
  4. OPC UA (OPC Unified Architecture) written in the common subset of the C99 and
  5. C++98 languages. The library is usable with all major compilers and provides the
  6. necessary tools to implement dedicated OPC UA clients and servers, or to
  7. integrate OPC UA-based communication into existing applications. open62541
  8. library is platform independent. All platform-specific functionality is
  9. implemented via exchangeable plugins. Plugin implementations are provided for
  10. the major operating systems.
  11. open62541 is licensed under the Mozilla Public License v2.0. So the *open62541
  12. library can be used in projects that are not open source*. Only changes to the
  13. open62541 library itself need to published under the same license. The plugins,
  14. as well as the server and client examples are in the public domain (CC0
  15. license). They can be reused under any license and changes do not have to be
  16. published.
  17. OPC Unified Architecture
  18. ------------------------
  19. `OPC UA <http://en.wikipedia.org/wiki/OPC_Unified_Architecture>`_ is a protocol
  20. for industrial communication and has been standardized in the IEC 62541 series.
  21. At its core, OPC UA defines
  22. - an asynchronous :ref:`protocol<protocol>` (built upon TCP, HTTP or SOAP) that
  23. defines the exchange of messages via sessions, (on top of) secure
  24. communication channels, (on top of) raw connections,
  25. - a :ref:`type system<types>` for protocol messages with a binary and XML-based
  26. encoding scheme,
  27. - a meta-model for :ref:`information modeling<information-modelling>`, that
  28. combines object-orientation with semantic triple-relations, and
  29. - a set of 37 standard :ref:`services<services>` to interact with server-side
  30. information models. The signature of each service is defined as a request and
  31. response message in the protocol type system.
  32. The standard itself can be purchased from IEC or downloaded for free on the
  33. website of the OPC Foundation at https://opcfoundation.org/ (you need to
  34. register with a valid email).
  35. The OPC Foundation drives the continuous improvement of the standard and the
  36. development of companion specifications. Companion specifications translate
  37. established concepts and reusable components from an application domain into OPC
  38. UA. They are created jointly with an established industry council or
  39. standardization body from the application domain. Furthermore, the OPC
  40. Foundation organizes events for the dissemination of the standard and provides
  41. the infrastructure and tools for compliance certification.
  42. open62541 Features
  43. ------------------
  44. open62541 implements the OPC UA binary protocol stack as well as a client and
  45. server SDK. It currently supports the Micro Embedded Device Server Profile plus
  46. some additional features. Server binaries can be well under 100kb in size,
  47. depending on the contained information model.
  48. - Communication Stack
  49. - OPC UA binary protocol
  50. - Chunking (splitting of large messages)
  51. - Exchangeable network layer (plugin) for using custom networking APIs (e.g. on embedded targets)
  52. - Encrypted communication
  53. - Asynchronous service requests in the client
  54. - Information model
  55. - Support for all OPC UA node types (including method nodes)
  56. - Support for adding and removing nodes and references also at runtime.
  57. - Support for inheritance and instantiation of object- and variable-types (custom constructor/destructor, instantiation of child nodes)
  58. - Access control for individual nodes
  59. - Subscriptions
  60. - Support for subscriptions/monitoreditems for data change notifications
  61. - Very low resource consumption for each monitored value (event-based server architecture)
  62. - Code-Generation
  63. - Support for generating data types from standard XML definitions
  64. - Support for generating server-side information models (nodesets) from standard XML definitions
  65. Features on the roadmap for the 0.3 release series but missing in the initial v0.3 release are:
  66. - Encrypted communication in the client
  67. - Events (notifications emitted by objects, data change notifications are implemented)
  68. - Event-loop (background tasks) in the client
  69. Getting Help
  70. ------------
  71. For discussion and help besides this documentation, you can reach the open62541 community via
  72. - the `mailing list <https://groups.google.com/d/forum/open62541>`_
  73. - our `IRC channel <http://webchat.freenode.net/?channels=%23open62541>`_
  74. - the `bugtracker <https://github.com/open62541/open62541/issues>`_
  75. Contributing
  76. ------------
  77. As an open source project, we invite new contributors to help improve open62541.
  78. Issue reports, bugfixes and new features are very welcome. The following are
  79. good starting points for new contributors:
  80. - `Report bugs <https://github.com/open62541/open62541/issues>`_
  81. - Improve the `documentation <http://open62541.org/doc/current>`_
  82. - Work on issues marked as `easy hacks <https://github.com/open62541/open62541/labels/easy%20hack>`_