Run gui-backend.sh on the Ccaffeine host using the appropriate port and the task0_gui_rc rc file. The command will look something like:

gui-backend.sh --port 3314 --ccafe-rc $TUTORIAL_SRC/components/examples/task0_gui_rc

depending on the port number assigned to you, and whether or not you've copied the rc file to your local directory.

In the Ccaffeine host terminal window, you will see something like:

(Ccaffeine host)
(19419) CmdLineClientMain.cxx: execName is ccafe-client 
(19419) CmdLineClientMain.cxx: runType is CLIENT
(19419) CmdLineClientMain.cxx: If execName is unexpected, blame your MPI startup script.
(19419) CmdLineClientMain.cxx: If MPI_Init is unwanted, try adding the switch '--ccafe-mpi no' switch,
(19419) CmdLineClientMain.cxx: or try setenv CCAFE_USE_MPI 0 .
(19419) CmdLineClientMain.cxx: MPI_Init being called.
(19419) CmdLineClientMain.cxx: MPI_Init succeeded.
(19419) my rank: 0, my pid: 19419
(19419) MapEverythingToFile(pOut0, pErr0)
Type: Server

which is similar to what you saw running ccafe-single in Step 1 of Section 2.1, “A CCA Application in Detail”, except that in ccafe-client, MPI is configured “on” by default. The next-to-last line is special to ccafe-client (and ccafe-batch) and serves as a reminder that by default, the stdout and stderr output streams from these executables are funneled to the indicated files. This message appears (and the files are created, but with minimal content) even though we used the --ccafe-io2tty option.

Run the simple-gui.sh on the GUI host.

Once the GUI connects to Ccaffeine, Ccaffeine begins running the rc file it was invoked with. In the GUI host terminal window, you first see some startup messages from the GUI itself, followed by a series of messages as Ccaffeine processes the rc file and the GUI displays the results. These are debugging messages and can largely be ignored. In the Ccaffeine host terminal, you should see some additional messages as Ccaffeine processes the rc file, like:

(Ccaffeine host)
CCAFFEINE configured with babel.
CmdLineClient parsing ...

CmdContextCCAMPI::initRC: Found /san/homedirs/bernhold/task0_gui_rc.
# There are allegedly 31 classes in the component path

Finally, you should see a “gui>” prompt in the GUI host terminal window, and the GUI itself should have appeared on your display, looking something like this:

	Tip
	The default layout has the palette area fairly narrow. You can click-and-drag on the bar separating the palette and the arena to adjust the width.

As mentioned above, the task0_gui_rc sets up the path and performs the appropriate repository get-global commands. (Note that in this case, all of the available components have been included, for convenience, whereas in the previous command-line based procedures, the repository get-global commands appeared in two different places.)

At this point, you've completed the equivalent of the first three steps in Section 2.1, “A CCA Application in Detail” (as well as the additional repository get-global commands in Step 7) or in the rc file described in Section 2.2, “ Running Ccaffeine Using an rc File ”.

For the remainder of this procedure, each step will be functionally equivalent to the matching step of the command-line based procedures described above. Please refer to those sections for more detailed explanations of what is happening “behind the scenes”.

We will begin by instantiating a drivers.CXXDriver component. Click-and-drag the component you want from the palette to the arena. When you release the mouse button in the arena, a dialog box will pop up prompting you to name this instance of the component. The default will be the last part of the component's class name (i.e. CXXDriver for drivers.CXXDriver) with a numerical suffix to insure the name is unique. The suffix starts at 0 and simply counts up according to the number of instances of that component you've created in that session. You can, of course, enter any instance name you like, as long as it is unique across all components in the arena, but for simplicity, we will always accept the default value in this Guide.

For the first application, you should instantiate

(you may notice some debugging messages in the GUI host terminal window as you do this), and your GUI should look something like this:

	Tip
	You can drag components around the arena to arrange them as suits you -- just click on the black area of the compoment and drag it to the new location. The positions have no bearing on the operation of the GUI or your application.

The next step is to begin making connections between the ports of your components. Click-and-release CXXDriver0's IntegratorPort uses port, then click-and-release MonteCarlo0's IntegratorPort provides port and a red line should be drawn between the two:

Tip

If you hover the cursor over a particular port on a component, a “tool tip” box will pop up with the port's name and type based on the arguments to the addProvidesPort or registerUsesPort calls in the component's setServices method. This can be useful for double checking to make sure you're connecting matching ports. Also notice that when you hover over a particular port (either uses or provides), matching ports of the opposite type (either provides or uses) will be highlighted.

	Note
	You can move components around even after their ports are connected -- the connections will automatically rearrange. There is no harm in connections crossing each other, nor in connections passing behind other components (though of course they may make it harder to interpret the “wiring diagram” correctly).

Complete the first application by making the following connections:

At this point, your GUI should look something like:

The application is now fully assembled and is ready to run. If you click-and-release the GoPort button on the CXXDriver0 component, you should see the result appear in the Ccaffeine host terminal, “Value = 3.141449” and the message “##specific go command successful” in the GUI host terminal.

Next, we're going to use some of the other components to assemble a different application using the

components. Since they're already in the palette, you can instantiate them in the same way as Step 4.

Tip

As we've mentioned, wiring diagrams can become hard to interpret when they become cluttered, as is the case with the screen shot above. To help interpret the diagram, remember the following: “Wires” only connect to the sides of ports -- on the left side of provides ports (on the left side of the component), or on the right side of uses ports. Connections are never made to the top or bottom of a component. The GUI's wire-drawing algorithm is aware only of the two components that are being connected. It will make no attempt to avoid other components or other wires. So wires can pass behind components without connecting to any of their ports, and wires may overlap. If you're still uncertain how to interpret the connections try rearranging the components slightly. Connections attached to the component will follow as you drag it around, but others not associated with that component will remain unchanged.

Next, we break the port connections we don't need so we can reconnect to the new components. Right-click on the IntegratorPort (either the user or the provider) and a dialog box will pop up asking you to confirm that you want to break the connection. You will need to break the following connections:

The fact that MonteCarlo0 remains connected to RandNumGenerator0 is immaterial because neither component will be used in the remainder of this exercise.

	Note
	Step 7 and Step 8 could have been done in either order.

Assemble the new application by making the following connections:

Click-and-release the GoPort button on the CXXDriver0 component, you should see the result appear in the Ccaffeine host terminal, “Value = 3.141553” and the message “##specific go command successful” in the GUI host terminal.

Finally, create a third application by replacing PiFunction0 with CubeFunction0. When you click on the GoPort you should get “Value = 0.250010” in the Ccaffeine host terminal.

To politely exit the GUI, select File → Quit. This will terminate both the GUI and the backend ccafe-client sessions.

	Tip
	If you've used the GUI to setup and start a long-running simulation, and you don't want to leave the GUI running continuously, you can use the File → Detach option to close the GUI but leave the backend running. However it is currently impossible to reattach to a running session.