Open62541 Dart Bindings - WIP

Currently working

There is a raw example where read and subscribe are implemented.

Notes

I am using the master branch of open62541 to have this commit https://github.com/open62541/open62541/pull/5445

When creating the build directory use -DUA_ENABLE_INLINABLE_EXPORT=ON to not expose the methods as static inline otherwise the functions will be skipped.

complete command

Multithreading has to be off. We need to run open65421 periodically. Dart does not support multithreading.

Create the .so file and the regenerate the bindings.

Create a directory to build open62541

mkdir open62541_build

Run this from the open62541_build directory

cmake ../open62541/ -DBUILD_SHARED_LIBS=ON -DUA_ENABLE_INLINABLE_EXPORT=ON -DCMAKE_INSTALL_PREFIX=install -DUA_BUILD_EXAMPLES=OFF -DUA_BUILD_UNIT_TESTS=OFF -DUA_ENABLE_AMALGAMATION=ON -DUA_MULTITHREADING=0
make

Optionally you can set the log_level inside open62541

cmake ../open62541/ -DBUILD_SHARED_LIBS=ON -DUA_ENABLE_INLINABLE_EXPORT=ON -DCMAKE_INSTALL_PREFIX=install -DUA_BUILD_EXAMPLES=OFF -DUA_BUILD_UNIT_TESTS=OFF -DUA_ENABLE_AMALGAMATION=ON -DUA_MULTITHREADING=0 -DUA_LOGLEVEL=100
make

Where the levels are defined as follows

600: Fatal
500: Error
400: Warning
300: Info
200: Debug
100: Trace

Now modify the open62541_build/open62541.h file, remove the bitfields from

• UA_DiagnosticsInfo
• UA_DataValue

and replace with a single byte. In my experimentation I have added a static_assert and the size remains the same. I am not sure if this will cause issues in the future but seems to generate a much larger section of the library. Example of change

23244,23250c23244,23251
<     UA_Boolean    hasSymbolicId          : 1;
<     UA_Boolean    hasNamespaceUri        : 1;
<     UA_Boolean    hasLocalizedText       : 1;
<     UA_Boolean    hasLocale              : 1;
<     UA_Boolean    hasAdditionalInfo      : 1;
<     UA_Boolean    hasInnerStatusCode     : 1;
<     UA_Boolean    hasInnerDiagnosticInfo : 1;
---
>     // UA_Boolean    hasSymbolicId          : 1;
>     // UA_Boolean    hasNamespaceUri        : 1;
>     // UA_Boolean    hasLocalizedText       : 1;
>     // UA_Boolean    hasLocale              : 1;
>     // UA_Boolean    hasAdditionalInfo      : 1;
>     // UA_Boolean    hasInnerStatusCode     : 1;
>     // UA_Boolean    hasInnerDiagnosticInfo : 1;
>     UA_Byte          hasBitfield;

Then you can generate the bindings with

dart run ffigen

Some clang errors have been turned off to disable errors coming from macos's pthread library and other standard libraries