013. web api
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# API has various meanings
# Web api generally means xml, json, csv file data which are opened on web
# Data on web actually can be called web api
# Data opened on web can be called open api
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# Process of using web api is that you register web api service,
# then, you declare that you want to get data,
# then, you can obtain data
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# You can see list of api you can use in Korea in following site
# apistore.co.kr
# You can collect data by using above site
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# Now that we've learned how to parse html document,
# every data on web can be target to be collected
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# You can see list of data and rule which owner of data claims in the following site
# www.xxx.com/robots.txt
# user-agent:* disallow:/ means that all user can't get everything