The POCO C++ Libraries (POCO stands for POrtable COmponents) are
open source C++ class libraries that simplify and accelerate the
development of network-centric, portable applications in C++. The
libraries integrate perfectly with the C++ Standard Library and
fill many of the functional gaps left open by it. Their modular
and efficient design and implementation makes the POCO C++ Libraries
extremely well suited for embedded development, an area where the
C++ programming language is becoming increasingly popular, due to
its suitability for both low-level (device I/O, interrupt handlers,
etc.) and high-level object-oriented development. Of course, the
POCO C++ Libraries are also ready for enterprise-level challenges.

Homepage:
http://www.pocoproject.org/
