title: ESB or SCA -- Architectural perspective
body: <p>How does modern day <strong>ESB</strong> compare to <strong>SCA</strong> ( in terms of routing / aggregating services ) ?  </p>
  
  <p>This is what i think [ from past experience ].</p>
  
  <p>Lets say we have two services S1 and S2, and a composite service S3 which is composed of S1 and S2. Assume S1 and S2 have two different endpoints and protocols.  </p>
  
  <p><strong>How to access using ESB?</strong>  ( WSO2 / Apache Synapse )</p>
  
  <ol>
  <li>We can access S1 first and S2 second ( creating a pipe )</li>
  <li>We can access S3 directly to provide output.
  (protocol conversion / transformation / orchestration ) being done here.</li>
  </ol>
  
  <p><strong>How to access using SCA?</strong>  ( Apache Tuscany )</p>
  
  <ol>
  <li>Lookup S1 first and S2 next ( using SCA API )</li>
  <li>Create a composite S3 out of S1 and S2 and invoke S3
  ( protocol conversion / transformation / orchestration ) being done here.</li>
  </ol>
  
  <p>Are people out there using both SCA composition and ESB Orchestration together?</p>