Functionally speaking, Remote Manager is part of OIM Integration Services(Business Services Tier). It is a OIM server component that runs on a target system computer. It provides the network and security layer required to integrate with applications that do not have network-aware APIs or do not provide security. It is built as a lightweight Remote Method Invocation (RMI) server. The communication protocol is RMI tunneled through Hypertext Transfer Protocol/Secure (HTTP/S).
OR in simpler terms, while performing provisioning or reconciliation actions, OIM must communicate with the target to perform the business operations. To do so, OIM uses the target APIs to directly communicate with the target during provisioning and reconciliation. However, there are some cases where OIM cannot directly communicate with the target. For Eg:
a) The target is behind a firewall, and the target communication port is not exposed.
b) The target does not provide APIs that can be invoked over the network. OR
c) The target APIs cannot be invoked over a secure connection.
In these instances, instead of directly communicating with the target system, OIM must use an Oracle Identity Manager component that acts like a proxy. This component is known as remote manager.
The remote manager is used for:
a) Invoking non-remotable target APIs through Oracle Identity Manager
b) Invoking target APIs that do not support SSL over secure channel