Welcome to the Internet Communication Framework (ICF) space. This is the SCN WIKI starting point for topics around ICF.
The Internet Communication Framework (component BC-MID-ICF) is the middleware between the Internet Communication Manager (ICM, component BC-CST-IC) and the HTTP enabled ABAP applications. ICM communicates with the internet via HTTP and HTTPS protocols, while ICF communicates with the ABAP applications via their handler classes.
ICF services are entry points for HTTP enabled ABAP applications. ICF provides a framework where these services can be configured. Configuration possibilities include adjusting the logon sequence, the SSL requirement, the usage of HTTP security sessions, the behavior in case of HTTP errors, etc. While ICF provides this framework, each application can create and configure their own ICF services in the transaction SICF.
ICF also provides the System Logon functionality, which is a configurable logon page used by various applications (BSP, WebDynpro, WebGUI, etc.). The component for the ICF System Logon is BC-MID-ICF-LGN.