# IBM Visualization Data Explorer Programmer's Reference

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## 17.3 Example 2: maptoplane.c

The second example which we will discuss is maptoplane.c. This sample program starts the Data Explorer user interface in `-edit` mode, and then loads a visual program (see Figure 13).

Figure 13. maptoplane.net

The visual program contains two DXLInput tool which can receive values from the DXLink program. One is named `file_to_import`, and the other is named `maptoplane_point`. The DXLink program sends the filename to `file_to_import`, and then sends several different values to `maptoplane_point`. The program is run and for each execution, statistics are computed on the resulting MapToPlane. The maximum value on the plane is passed to a DXLOutput tool labeled `maptoplane_max`. In maptoplane.c, a handler has been installed for output coming from `maptoplane_max`, and the handler simply prints the value to the terminal.

    #include <stdio.h>
    #include "dx/dxl.h"
    #ifndef BASE
    #define BASE "/usr/share/dx"
    #endif
    void SyncAfterExecute(DXLConnection *conn)
    {
      int status=1;
       while (status) {
          sleep(1);
          if (DXLIsMessagePending(conn))
             DXLHandlePendingMessages(conn);
          DXLGetExecutionStatus(conn, &status);
       }
    }
    /*
     * this routine simply prints the maximum value as received from the
     * DXLOutput tool
     */
    void max_handler(DXLConnection *conn, const char *name, const char *value,
                     void *data)
    {
       printf("max value = %s\n", value);
    }
    main(int argc, char *argv[])
    {
        DXLConnection *conn = NULL;
        char result[100];
        int status;
        /*
         * Start Data explorer user interface in -edit mode, with certain
         * in -edit mode, with certain menus turned off.
         */
        conn = DXLStartDX("dx -edit -noExitOptions -noExecuteMenus -noConnectionMenus",
                          NULL);
        if (conn == NULL)
        {
            fprintf(stderr,"Could not connect\n");
            perror("DXLStartDX");
            exit(1);
        }
        /*
         *  Set the handler for the DXLOutput tool which is labelled
         *  "maptoplane_max"
         */
        DXLSetValueHandler(conn, "maptoplane_max", max_handler, NULL);
        /*
         * Load the visual program to run. Set the value of the DXLInput
         * tool which is labelled "file_to_import".
         * Also set the value of the DXLInput tool which is labelled
         * "maptoplane_point".
         */
        DXLLoadVisualProgram(conn, BASE"/samples/dxlink/maptoplane.net");
        DXLSetString(conn, "file_to_import","/usr/share/dx/samples/data/temperature");
        DXLSetValue(conn, "maptoplane_point", "[0 5000 5000]");
        /*
         * Execute the visual program and check for input from maptoplane_max.
         */
        DXLExecuteOnce(conn);
        SyncAfterExecute(conn);
        /* Change the value for the DXLInput tool labelled "maptoplane_point
         * and execute again.
         */
        DXLSetValue(conn, "maptoplane_point", "[10000 5000 5000]");
        DXLExecuteOnce(conn);
        SyncAfterExecute(conn);
        /* Change the value for the DXLInput tool labelled "maptoplane_point
         * and execute again.
         */
        DXLSetValue(conn, "maptoplane_point", "[20000 5000 5000]");
        DXLExecuteOnce(conn);
        SyncAfterExecute(conn);
        /* Change the value for the DXLInput tool labelled "maptoplane_point
         * and execute again.
         */
        DXLSetValue(conn, "maptoplane_point", "[30000 5000 5000]");
        DXLExecuteOnce(conn);
        SyncAfterExecute(conn);
        /* Change the value for the DXLInput tool labelled "maptoplane_point
         * and execute again.
         */
        DXLSetValue(conn, "maptoplane_point", "[50000 5000 5000]");
        DXLExecuteOnce(conn);
        SyncAfterExecute(conn);
        printf("Hit return to quit:");
        gets(result);
        DXLExitDX(conn);
    }

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