I want build a search service for one particular thing. The data is freely available out there, via free classified services, and a host of other sites.
Are there any building blocks, e.g. open-source crawlers that I would customize - rather than build from scratch, that I can use?
Any advice on building such a product? Not just technical, but any privacy/legal things that I might need to take into consideration.
E.g. do I need to 'give credit' where the results are from and put a link to the original - if I get them from many places?
Edit: By the way, I am using GWT with JS for the front-end, haven't decided on the language for the back-end. Either PHP or Python. Thoughts?
There are few blocks in python you can use.
I use first two for my needs; f.e. it needs 20 lines of code to get an automatic testing tool for a 3-stage poll, with simulation of waiting for user entering data and so on.