title: 503service unavailable in Salesforce
body: <p>My goal is to create a REST API Integration from Salesforce to SAP application.</p>
  
  <p>SUCCESS Through Chrome APP</p>
  
  <p>1. All I need to do is retrieve values from sap application through the REST API. When I tried to use the Chrome APP 'Advanced Rest Client' and have passed the appropriate URL and Content with POST method I was able to retrieve the values from local server database.</p>
  
  <p>For EG : If I pass request 92126 then I was able to get response  'SAN DIEGO' which is correct.</p>
  
  <p>Here is the link (<a href="https://chrome.google.com/webstore/detail/advanced-rest-client/hgmloofddffdnphfgcellkdfbfbjeloo?hl=en-US" rel="nofollow noreferrer">https://chrome.google.com/webstore/detail/advanced-rest-client/hgmloofddffdnphfgcellkdfbfbjeloo?hl=en-US</a>) for Advanced REST Client.</p>
  
  <p>PROBLEM from Salesforce :</p>
  
  <ol>
  <li>I had created a remotesite setting </li>
  <li>When I created this REST class in SAlesforce and tried invoking the End Point then it's throwing this error.</li>
  </ol>
  
  <blockquote>
    <p>System.HttpResponse[Status=Service Unavailable, StatusCode=503]</p>
  </blockquote>
  
  <p>As the web api url which is provided to us is in local sql server i.e hosted in private, as we know in Salesforce for making callouts the URLs must be in public. But the URL is in private only for the security reasons not hosted in public. We should achieve it, any way is there to achieve it? What change should be done in Salesforce or server to communicate to each other, and allows to make the callout?</p>