I am planning to implement Hiawatha web server on a non-linux platform which is uC/OS-II RTOS.
I need help to port the Linux dependent API's to RTOS platform.
Kindly let me if there are already build libraries that I can use to port Linux on RTOS.
Thanks in Advance
Any code that uses more than just the standard C library will require some porting effort - the extent to which non-standard and OS specific libraries and calls are made will determine the effort required or even the feasibility of such a port.
Most Linux code of any complexity will require a POSIX API and networking code will probably use BSD sockets. Multi-threaded code would likley use pthreads. uC/OS-II has neither of these; it deals with only scheduling, timing, synchronisation and inter-process communication; it is a scheduling kernel, not a full OS in the same sense as Linux - it does not even have a file system - a requirement of most Linux code. Of course adding additional libraries and extensions may provide some or all of what you may need.
Moreover uC/OS-II's simple one-thread-per-priority-level scheduler would make typical Linux multi-threaded code hard to schedule in the manner intended. Most RTOSes (including uC/OS-III) support round-robin/time-sliced scheduling of tasks at the same priority level, but uC/OS-II does not; possibly making it unsuitable for this task.
Something more sophisticated that uC/OS-II may be in order, or perhaps using code more suited to uC/OS-II perhaps. eCos for example is a far more complete RTOS for embedded systems; it is open-source and includes a POSIX API, file-system support and a socket API. It would be far easier to port Linux code to that. Equally there are many lightweight embedded webserver examples that are probably more suited to uC/OS-II and other simple RTOS or even no OS at all. LwIP for example is a TCP/IP stack for small embedded systems for which uC/OS-II ports exist and for which there are web server examples.
The point is that Linux are uC/OS-II are not comparable; one requires < 10Kb of code, the other has a minimal foot-print of about 4Mb! To get Linux code to run on such a system will require you to add a lot of additional code to provide the missing services, and it may not be feasible on your target platform.
[Edit: 08 July 2012]
Have you considered using Micrium's own TCP/IP stack and μC/HTTPs web-server add-on? It is likley to be better integrated to uC/OS-II and provide better performance than non-RTOS specific third-party code.