Well,This post is to explain very shortly about soa-infra.
Heard of it? It's an J2EE Compliant application and can be deployed over Weblogic Server.It's responsible for managing composites that you deploy and it manages composites life cycle.
Generally, during development phase, you deploy soa composite application designed in Oracle JDeveloper to soa-infra.using soa-infra application we should be able to monitor soa composite apps or individual composite instances.
Using Enterprise Manager(EM) one can configure soa-infra to it and monitor the states of composites that's being deployed.