This is the third release candidate of what will become open62541 v0.3. The API has been frozen and only backwards-compatible patches will be applied before v0.3. Compared to previous release candidates, this version includes additional bugfixes and small improvements under the hood while keeping the API stable.
The full list of changes compared to the previous release candidates v0.3-rc2 can be found here: 0.3-rc2...v0.3-rc3
open62541 (http://open62541.org) is an open source and free implementation of OPC UA (OPC Unified Architecture) written in the common subset of the C99 and C++98 languages. The library is usable with all major compilers and provides the necessary tools to implement dedicated OPC UA clients and servers, or to integrate OPC UA-based communication into existing applications. open62541 library is platform independent. All platform-specific functionality is implemented via exchangeable plugins. Plugin implementations are provided for the major operating systems.
open62541 is licensed under the Mozilla Public License v2.0. So the open62541 library can be used in projects that are not open source. Only changes to the open62541 library itself need to published under the same license. The plugins, as well as the server and client examples are in the public domain (CC0 license). They can be reused under any license and changes do not have to be published.
The library is available in standard source and binary form. In addition, the single-file source distribution merges the entire library into a single .c and .h file that can be easily added to existing projects. Example server and client implementations can be found in the /examples directory or further down on this page.
The most important changes compared to the 0.2 branch are as follows.
Support for encrypted SecureChannels
Support for node-based access control
Support for client-side subscriptions handling in the background
Support for custom storage layers for the information model
Improved lifecycle handling for nodes (constructors and destructors)
Improved documentation