CL_GUI_FRONTEND_SERVICES 
General Description
The class CL_GUI_FRONTEND_SERVICES contains a number of methods that allow ABAP programs to execute operating system functionality on the client PC. The PC on which the Graphical User Interface (GUI) is running is called the client PC. This class isolates ABAP programs from the operating system the client is running on and the Graphical User Interface implementation used.
ABAP applications should be programmed as platform independent as possible. This means that applications should try to avoid using functionality that is not supported for all of the supported GUIs.
In addition to making information about the client PC and the GUI used available certain clipboard, environment variable, file system and registry operations are provided as well. It is also possible to start programs or display documents using methods from the class CL_GUI_FRONTEND_SERVICES.
The class CL_GUI_FRONTEND_SERVICES supports the SAP GUI for Windows, the SAP GUI for the Java Environment and the SAP GUI for HTML. WebDynpro applications are not supported.
Methods
The methods of the class CL_GUI_FRONTEND_SERVICES can be grouped into the following categories:
The clipboard functions allow access to the clipboard on the client computer.
Environment Variable Functions:
Provide access to the environment variables of the client process.
This group encompasses methods for accessing, creating, modifying and deleting files or directories on the client.
The file upload/download functions allow the data transfer between internal ABAP tables on the server and files on the client.
The functions in this group provide information about the GUI being used.
Operating System Information Functions:
Information about the operating system running on the client PC is made available by the operating system information functions.
Program Execution/Document Display:
The execute method allows execution of programs and the display of documents.
The registry functions provide functionality for accessing and modifying the registry.
Generation of screenshot of current topmost modal frontend window for current mode.
The system information functions make information about the client PC available.
While most of the methods of the class CL_GUI_FRONTEND_SERVICES call CL_GUI_CFW=>FLUSH internally there are a number of function where this is not the case. If the caller needs to call the FLUSH himself, this is noted in the documentation.