将大型经典ASP页面迁移到php？

We've got a large classic asp application and we consider migrating to either asp.net or php. I don't want to talk about the pros and cons of either one, but I'd rather like to know whether there are ways to avoid a complete rewrite in one shot when migrating to php. We simply can't stop maintaining the current codebase just to do a rewrite. So things have to go hand in hand.We've got a large classic asp application and w