now that you have an overview of the steps to comelet' get to work if you followed the instructions in the appendixyou should now have local instance of elasticsearch up and running first comes data retrievalyou need information on the different diseases you have several ways to get that kind of data you could ask companies for their data or get data from freebase or other open and free data sources acquiring your data can be challengebut for this example you'll be pulling it from wikipedia this is bit ironic because searches on the wikipedia website itself are handled by elasticsearch wikipedia used to have its own system build on top of apache lucenebut it became unmaintainableand as of january wikipedia began using elasticsearch instead wikipedia has lists of diseases pageas shown in figure from here you can borrow the data from the alphabetical lists figure wikipedia' lists of diseases pagethe starting point for your data retrieval you know what data you wantnow go grab it you could download the entire wikipedia data dump if you want toyou can download it to wiki/data_dump_torrents#enwiki of courseif you were to index the entire wikipediathe index would end up requiring about gb of storage feel free to use this solutionbut for the sake of preserving storage and bandwidthwe'll limit ourselves in this book to pulling only the data we intend to use another option is scraping the pages you require like googleyou can make program crawl through the pages and retrieve the entire rendered html this would do the trickbut you' end up with the actual htmlso you' need to clean that up before indexing it alsounless you're googlewebsites aren' too fond of crawlers scraping their web pages this creates an unnecessarily high amount of trafficand if enough people send crawlersit can bring the http server to its