These are three major Infra-structure Components for Fusion application within middelware :

1) Oracle Enterprise Crawl and Search Framework (ECSF)

Oracle Enterprise Crawl and Search Framework (ECSF): Oracle Enterprise Crawl and Search Framework enables the exposure of application context information on various business objects to enable full-text transactional search.

2) Oracle Enterprise Scheduler

This Enables you to manage and schedule jobs for Oracle Fusion Applications. read this for details.

Oracle Enterprise Scheduler Service provides the ability to run different Job Types, including: Java, PL/SQL, and Binary Scripts, distributed across the nodes in an OracleAS Cluster. Oracle Enterprise Scheduler Service runs these jobs securely, with high availability and scalability, with load balancing and provides monitoring and management through Oracle Enterprise Manager.

3) Applications Core aka Oracle Fusion Middleware Extensions for Applications

• Applications Core(ApplCore) aka Oracle Fusion Middleware Extensions for Applications, provides design time and runtime infrastructure to help standardize complex development patterns for Oracle Fusion Applications. These simplifies the development process of these patterns and provides a consistent user experience, Pattern in Fusions are typically Flexfields, hierarchical relationships (Trees), data security, and UI patterns.
• Applications Core provides shared libraries referenced by all the Oracle Fusion Applications, a standalone application for application setup and configuration, an Oracle JDeveloper extension to seamlessly integrate our components with the rest of the Oracle Fusion Applications technology stack, PLSQL API's, C libraries, and common seed data.

The product families use the following common core framework and infrastructure for Oracle Fusion Applications.