The "intercoms" category provides an expandable command interpreter. It is the key mechanism of Geant4 to realize secure user interactions of all categories without being annoyed by the dependencies among categories. The direct use of Geant4 classes in a C++ program offers a first ground level of interactivity, i.e., the batch session. As seen in the examples/novice/N01, Geant4 commands and macros are to be hard-coded in the program. To avoid too much programming, the "intercoms" category provides the abstract class G4UIsession that captures interactive commands . The concrete implementation of the user interface and Graphical User Interfaces (GUI) is left to the interfaces category. This interfacing strategy opens an important door towards various user interface tools and allows Geant4 to utilize the state-of-the-art GUI tools such as Motif, Qt, and Java etc..The richness of the collaboration has permitted for developers to offer various user interfaces to the Geant4 command system. Currently available are the following; Character terminal (dumb terminal and tcsh(bash)-like terminal), the default user interface of Geant4, Xm, Win32, Qt variations of the upper terminal by using a Motif, Qt or Windows widget to retrieve commands, and GAG, a fully Graphical User Interface and its network extension GainServer of the client/server type. Full implementation of the character terminals (1 and 2) is included in the standard Geant4 distribution in the source/interfaces/basic directory. As for GAG, the front-end class is included in the Geant4 distribution in the source/interfaces/GAG directory, while its partner GUI package MOMO.jar is available in the standard Geant4 distribution under the environments/MOMO directory. MOMO.jar, Java archive file, contains not only GAG, but also GGE and other helper packages. Supplementary information is available from the author's Webpage(see URL below). GAG, GainServer's client GUI Gain: http://www-geant4.kek.jp/~yoshidah These interfaces open a session on the character terminal. G4UIterminal runs on all platform supported by Geant4, including cygwin on Windows, while G4UItcsh runs on Solaris and Linux. G4UItcsh supports user-friendly key bindings a-la-tcsh (or bash); ^A move cursor to the top ^B backward cursor ([LEFT] cursor) ^C (except Windows terminal) abort a run (soft abort) during event processing. A program will be terminated while accepting a user command. ^D delete/exit/show matched list ^E move cursor to the end ^F forward cursor ([RIGHT] cursor) ^K clear after the cursor ^N next command ([DOWN] cursor) ^P previous command ([UP] cursor) TAB command completion DEL backspace BS backspace In addition, the following string substitutions are supported; %s current application status %/ current working directory %h history number These interfaces are versions of G4UIterminal implemented over libraries Motif, Qt and WIN32 respectively. G4UIXm uses the Motif XmCommand widget, G4UIQt the Qt dialog widget, and G4UIWin32 the Windows "edit" component to do the command capturing. These interfaces are useful if working in conjunction with visualization drivers that use the Xt library, Qt library or the WIN32 one. A command box is at disposal for entering or recalling Geant4 commands. Command completion by typing “TAB” key is available on the command line. The shell commands "exit, cont, help, ls, cd..." are also supported. A menu bar could be customized through the AddMenu and AddButton method. Ex: /gui/addMenu test Test /gui/addButton test Init /run/initialize /gui/addButton test "Set gun" "/control/execute gun.g4m" /gui/addButton test "Run one event" "/run/beamOn 1" G4UIXm runs on Unix/Linux with Motif. G4UIQt run everywhere with Qt. G4UIWin32 runs on Windows. They are the front-end classes of Geant4 which make connection with their respective graphical user interfaces, GAG (Geant4 Adaptive GUI) via pipe, and Gain (Geant4 adaptive interface for network) via sockets. While GAG must run on the same system (Windows or Unixen) as a Geant4 application, Gain can run on a remote system (Windows, Linux, etc.) in which JRE (Java Runtime Environment) is installed. A Geant4 application is invoked on a Unix (Linux) system and behaves as a network server. It opens a port, waiting the connection from the Gain. Gain is capable to connect to multiple Geant4 "servers" on Unixen systems at different institutes. Client GUIs, GAG and Gain have almost similar look-and-feel. So, GAG's functionalities are briefly explained here. Please refer to the above URL for details. Using GAG, user can select a command, set its parameters and execute it. It is adaptive, in the sense that it reflects the internal states of Geant4 that is a state machine. So, GAG always provides users with the Geant4 commands which may be added, deleted, enabled or disabled during a session. GAG does nothing by itself but to play an intermediate between user and an executable simulation program via pipes. Geant4's front-end class G4UIGAG must be instantiated to communicate with GAG. GAG runs on Linux and Windows. If MOMO.jar is in your CLASSPATH, it can be run by a command; %java -jar MOMO.jar GAG has following functions. GAG Menu: The menus are to choose and run a GEANT4 executable file, to kill or exit a GEANT4 process and to exit GAG. Upon the normal exit or an unexpected death of the Geant4 process, GAG window are automatically reset to run another GEANT4 executable. GEANT4 Command tree: Upon the establishment of the pipe connection with the GEANT4 process, GAG displays the command menu, using expandable tree browser whose look and feel is similar to a file browser. Disabled commands are shown in opaque. GAG doesn ’t display commands that are just below the root of the command hierarchy. Direct type-in field is available for such input. Guidance of command categories and commands are displayed upon focusing. GAG has a command history function. User can re-execute a command with old parameters, edit the history, or save the history to create a macro file. Command Parameter panel: GAG's parameter panel is the user-friendliest part. It displays parameter name, its guidance, its type(s) (integer, double, Boolean or string), omittable, default value(s), expression(s) of its range and candidate list(s) (for example, of units). Range check is done by intercoms and the error message from it is shown in the pop-up dialog box. When a parameter component has a candidate list, a list box is automatically displayed . When a file is requested by a command, the file chooser is available. Logging: Log can be redirected to the terminal (xterm or cygwin window) from which GAG is invoked. It can be interrupted as will, in the middle of a long session of execution. Log can be saved to a file independent of the above redirection . GAG displays warning or error messages from GEANT4 in a pop-up warning widget. The libraries that don't depend on external packages are created by default, using Geant4 configure scripts. They include G4UIterminal, G4UItcsh and G4UIGAG in libraries libG4UIbasic.a/so and libG4UIGAG.a/so. G4UIGainServer.o is packed in the libG4UIGAG. To make the libraries of G4UIXm, G4UIQt and G4UIWin32 , respective environment variables G4UI_BUILD_XM_SESSION, G4UI_BUILD_QT_SESSION or G4UI_BUILD_WIN32_SESSION must be set explicitly before creating libraries. However, if the environment variable G4UI_NONE is set, no interface libraries are built at all. The scheme of building the user interface libraries is specified in "$G4INSTALL/config/G4UI_BUILD.gmk" makefile and the dependencies on the external packages are specified in "$G4INSTALL/config/interactivity.gmk". To use a given interface (G4UIxxx where xxx = terminal,Xm, Win32, Qt, GAG, GainServer) in your program, you can do it by two ways : Calling G4UIxxx directly : #include "G4Uixxx.hh" // to instantiate a session of your choice and start the session G4UIsession* session = new G4UIxxx; session->SessionStart(); // the line next to the "SessionStart" is necessary to finish the session delete session; Note : For a tcsh session, the second line must be (See the examples in "examples/novice/N0x" in which the terminal session is used) : G4UIsession* session = new G4UIterminal(new G4UItcsh); Using G4UIExecutive (implement in all novice examples) : // to include the class definition in the main program: #ifdef G4UI_USE #include "G4UIExecutive.hh" #endif // to instantiate a session of your choice and start the session #ifdef G4UI_USE G4UIExecutive* ui = new G4UIExecutive(argc,argv); ui->SessionStart(); // the line next to the "SessionStart" is necessary to finish the session delete ui; #endif The two methods are similar. If you want to choose between several viewer driver at load, with the first method you will have to write : // to include the class definition in the main program: #if defined(G4UI_USE_TCSH) #include "G4UIterminal.hh" #include "G4UItcsh.hh" #elif defined(G4UI_USE_XM) #include "G4UIXm.hh" .... #endif #if defined(G4UI_USE_TCSH) session = new G4UITerminal(new G4UITerminal); #elif defined(G4UI_USE_XM) session = new G4UIXm(argc,argv); #elif ... That is not realy simple. The best way to do this is the second method : #ifdef G4UI_USE #include "G4UIExecutive.hh" #endif ... // to instantiate a session of your choice and start the session // G4UIExecutive will open for you the good driver (depending on G4UI_USE_xxx flags) #ifdef G4UI_USE G4UIExecutive* ui = new G4UIExecutive(argc,argv); #endif If the user wants to deactivate the default signal handler (soft abort) raised by "Ctr-C", the false flag can be set in the second argument of the G4UIterminal constructor like; G4UIsession* session = new G4UIterminal(new G4UItcsh, false). Again, environment variable must be preset to select a given interface. But for your convenience, some of them are set by defaults. G4UIterminal, G4UItcsh, G4UIGAG and G4UIGainServer can be used without setting any environment variables. Sessions not needing external packages or libraries are always built (see "G4UI_BUILD.gmk") and linked, so the user can instantiate one of these sessions without rebuilding the libraries and without setting any environment variables. For backwards compatibility with user code, as typified by geant4/examples main programs, the C-pre-processor variables corresponding to the original environment variables for the above three (i.e., G4UI_USE_TERMINAL, G4UI_USE_TCSH and G4UI_USE_GAG ) are set. However, if he/she sets no environment variables, then the C-pre-processor variable G4UI_USE_TERMINAL is set by default, although there is no need to use it. The environment variable G4UI_USE_XM, G4UI_USE_QT or G4UI_USE_WIN32 must be set to use the respective interface. The file "$G4INSTALL/config/G4UI_USE.gmk" resolves their dependencies on external packages. If the environment variable G4UI_NONE is set, no external libraries are selected. Also, for your convenience, if any G4UI_USE_XXX environment variable is set, then the corresponding C-pre-processor flag is also set. However, if the environment variable G4UI_NONE is set, no C-pre-processor flags are set.