Crawler Collecting Information for Oracle SES: This graphic shows remote sources in a box in the top left. The remote sources are a database, Web sites, Fusion Applications, an e-mail server, and an OracleAS Portal server. A crawler collects these sources and sends them to a crawler plug-in. The crawler plug-in can go back and forth to other sources and remote applications. The middle tier includes the end-user GUI, Web services, and the administration tool. At the bottom of the graphic is a box for the metadata layer. It includes cached docs, index, metadata, source, schedules, source group, and others.