title: Rest API call to fetch data from multiple API providers in very minimal time : Example websites like makemytrip
body: <p>Websites like makemytrip fetches flight booking details from different airlines api providers like jetairways, indigo and so on.</p>
  
  <p>when we visit there home page we see flight booking details of various airlines.</p>
  
  <p>Since this information cant be cached. 
  How will they make rest calls to all those api providers assuming there can be 10k - 20k of airlines api providers to display data on there home/search page.</p>
  
  <p><strong>1) Will they make concurrent calls to all those api providers to fetch data, whenever we visit there home/search page ?</strong> </p>
  
  <p>But considering number of threads in the pool this would take time to fetch data and map them in the response object, which will cause delay in page load time.</p>
  
  <p><strong>2) If we think of storing these data in search engines like elastic search, this even wont help as the data is not latest one.</strong></p>
  
  <p>Even if we think of having a <strong>"scheduler job"</strong> which makes rest calls to api providers to get latest data every 5 minutes and store in Elastic search. This would make display stale data in that 5 minutes of span time.</p>