March-14-2002
/ jn
Introduction
Table is a program to display messages sent from
computers
in the local net. Computers in the local net can send messages (in a
defined format) via UDP broadcast. Table takes these messages from
the net and displays these depending on their severity and the
selected options.
The program can, but need not be called by specifying
parameters
on the command line:
table [ -f <logging file name>
-d <display
name> --h ]
<logging file name>
is the name of the file, where all messages are written if File
Output is selected. If no filename is specified, a filename effbg_messages.log
is
assumed.
Calling the program
normally will open the window displaying messages and the possible
options. In case of known errors it will open an error window
specifying the problem. A background process is started, which
listens to the net for broadcast messages and decodes known messages
and displays them. The last received message is always the first in
the table.
An Error message: ERROR
in setting up UDP Receive: The address is already in use (Die
Adresse wird bereits verwendet)
means, that
a program is already listening at the special UDP-port. Normally the
reason is that this program (maybe started by another user) is
already running on the computer.
The Display Window
After a successful start
of the program the table window is shown:
The parts of the window
consist of a table view showing the received messages, a menue
view, where one can select special features for the display, and some
special icons to start some actions.
In the table view
the last received message is always in the first row. Coming a new
message will shift all others one row down, which means the last
message in the table is lost. The table view contains:
Time: The
time can be a time which was directly inserted by the message
producing program or produced by the message handler of the sending
computer or by this program. It is always converted to Julian Date.
It can be displayed as only time of day or together with the Julian
Day Number selected in the menue. For that reason the incoming
messages are not sorted by time. They are only sorted how they
arrived to this program.
Icon: The
displayed icon refers to the severity of the message. The icon
display can be deselected by the menue.
Message:
The message is displayed as a character string, how it
was produced by the sending program. The form of the text display
(color, bold etc.) depends on the severity of the message. Which type
of messages shall be displayed can be selected by the menue.
Sender: The sender specifies the sending
program or
handler or computer. By the menue on can select to display only
messages from certain senders.
The icons in the top part have the following functions:
'What's
This ? Button: Clicking first on this button and then
clicking the graphical elements may display a deeper explanation of
the element and the displayed data.
Info
Button: Clicking this button delivers last information about
the program.
Max
Size Button: Clicking these buttons automatically changes the
size of the window to maximum screen size.
Running
Display: This small display shows whether the display loop of
the program is running. If the icon is green, it runs. If it is red,
there is a problem.
Stop/Continue
Button: Clicking this button changes from 'STOP'
(normal color) to 'CONTINUE' (red). It stops updating and
freezes the table display. The button changes to red with the label
'CONTINUE'. Clicking again changes to STOP and display will further
update.
The menue options
are divided into three parts:
Options:
Here one can select special options for the display or define whether
or not a log-file is written.
Messages
from ...: Here are selected the senders, from which the
messages are displayed in the table view. Other means all other
senders not specified before.
Type of
messages: Here one can define, whether all message types are
displayed or only certain types of messages.
Program Structure
The
program structure mainly consists of three C++ Object classes and two
main structures for the messages. One structure defines a single
message with all possible parameters (TABLE_MESSAGE), a second
one consist of many single messages of the before type and some
counters for the messages (MESSAGE_ALL). The MESSAGE_ALL
structure is
allocated in shared memory, so it can be accessed by other programs.
One object is
responsible for the graphical display and user interface:
TabDis1
In that part of
the program there are handled the actions of the user with the
graphical interface like the buttons and the select boxes. On the
other hand it constructs the main window and its child windows.
The main
member functions are:
void slot_Info();
void slot_display_stop();
void slot_default_Size();
Functions
serving the icons, if pressed
void slot_message_options();
void slot_message_sender();
void slot_message_type();
Functions
reading the different options
Another one runs
as an own sub-process:
Get_messageData
This
object handles the incoming messages from the net and places
them as a single TABLE_MESSAGE
in the MESSAGE_ALL structure. Counters in that
structure define the last message come in and the last message
displayed etc.. An UDP read connection on an certain port is
established to get all broadcast messages to that port.
The main member
functions are:
int UDPinit();
Setup the UDP
broadcast connection
int UDPread();
Read data
from UDP port
void interprete_data();
Select only
message data
void set_message(TABLE_MESSAGE
*m,double time,char
*sender,int
sever, int main_id,int sub_id,char *text, char *subtext=0);
Setup the
TABLE_MESSAGE structure
void write_message(TABLE_MESSAGE
m);
Fill message in MESSAGE_ALL
structure
The last object works with
the incoming
messages:
TabDispl
This program
continuously checks for new messages in the MESSAGE_ALL structure.
As first the new message will be examined
and
parameters of the TABLE_MESSAGE structure will be completed
(eg. time or sender). Then it tests whether an identical message
already came since a certain time ( ~10 sec.). In that case it will
not be displayed. Messages according to the selected options also
will not be displayed. If the message should be displayed, the table
will be shifted down and then displayed. In parallel the message is
written to the log-file.
The main member functions
are:
void
slot_table_update();
Main loop depending on a
timer
void check_newmessage();
Find a new message
bool compare_message(QTable
*t,int row1,int row2,double timediff,TABLE_MESSAGE ein);
Compare message with older
ones
bool filter_message(TABLE_MESSAGE
ein);
Filter out messages not to
display
void shift_rows_down(QTable
*t,int row1=0,int row2=0);
Shift table down
void write_line(QTable
*t,int
row, TABLE_MESSAGE ein);
Write new table row
