about NCBI BLAST

Hi

I am doing research on parallelizing BLAST. Thus, in my own source
code I want to interfere with the BLAST program. Before I use the
system( ) function to achieve, however I found that it can't achieve
my goal now. Are there other ways for using NCBI BLAST in my own
source code?

Could anyone please help me out?

Thanks!

-- 
LuoXi