How to Write a Focused Crawler by asp.net

I need to build the small Project using ASP.NET. for my master about "A Platform for Developing Semantic Web Portals"

In summary I need the following things:

How to build Focused web crawler using Asp.net . I started to build some basic but I need to some guide, resource and books.

Using this crawler, i need to find the some Web sites offer the same service as hotel Web sites

Please any body has any idea or resource or books. Please share with us.