Response-time analysis of composite Web services

Web services let programs submit requests to other programs over the Internet via open protocols and standards. Many traditional Web sites, including popular search engines like Google and large online bookstores are boosting their traffic through Web service APIs. A single Internet application can invoke many different Web services - for example, the metasearch engine WebSifter uses several online ontologies to refine a user´s request into a more meaningful query and then submits that query to various search engines in parallel. We call such applications composite Web services. Many important challenges stem from the quality-of-service issues in composite Web services. We address the impact of slow services on the overall response time of a transaction that uses several Web services in parallel.