RNA integrity and RNA fragmentation? - (Feb/03/2014 )

After RNA isolation and before following experiments, I know that RNA quality so called RNA integrity is so important. So why there is a RNA fragmentation kit? Do we need RNA intact or fragmented?

For high throughput sequencing, we read relatively short regions on one or both ends of cDNA fragments. Many mRNA fragments are quite long, and if we want to sequence those fragments to establish their frequency, we need to fragment the mRNA.