so_5_extra is a header-only and C++14 library with additional tools and extensions for SObjectizer.

At this moment so_5_extra contains an implementation of environment infrastructure on top of Asio, additional mbox types, implementation of shutdowner mechanism... But we have big plans for future versions of so_5_extra.

If you want to see something in so_5_extra you can tell us about it via info@stiffstream.com.

There are several reasons for development of so_5_extra as a separate library:

• we want to keep SObjectizer as a small project without big external dependencies. But we can use such heavy dependency as Asio for so_5_extra;
• SObjectizer contains features which are necessary for many users. But so_5_extra can contain features which can be required by a few users;
• a new feature can be added to SObjectizer only if it is proved that this feature is useful. But so_5_extra can be seen as a testing field for new ideas. If something from so_5_extra will be valuated as helpful and widely used it can be moved into SObjectizer with time;
• so_5_extra is a commercial project so it uses dual-license. But SObjectizer was and will be distributed under more permissive BSD-license.

so_5_extra uses dual-license:

• GNU Affero GPL v.3 for free use in OpenSource projects;
• a commercial license for use in closed source proprietary projects. It costs $120 for one developer per year.

Contact us at info@stiffstream.com for any questions related to so_5_extra licenses.