This program uses as input an external message buffer (MSG_BUFFER), which contains the messages sent by other tasks. The program detects the new messages. If a new one is found, it is sent via UDP Broadcast to the local net and is put in an internal buffer of the last read messages. But before the new message is compared with the messages in the internal buffer. If the same message already is present during the last ~10 seconds, the message is not sent, but only put in the internal buffer. If the message in the Message Buffer was sent with NO_TIME, the actual system time is added to the message.

Accessing the Message Buffer

The access to the external message buffer by other tasks is performed by special functions (see here). So, the message handler object file must first be loaded together with the external message buffer (MSG_BUFFER) to give the other tasks access to these functions and the buffer.

The functions and Macros are defined in a file: message_send_doc.cpp. It can be included like a header file in a general messageID-file describing the single messages (look here). All these functions are available, if the message handler is loaded. It is not necessary to start the message handler.

The following functions give access to the general message buffer:

(They put their messages in the message buffer.)

• int send_error(char *stxt,int severity,int mainID,int subID,char *sender,char *txt,double time);

• int send_terror(double time,char *stxt,int severity,int mainID,int subID,char *sender,char *txt);

• int send_info(char *stxt,int severity,int mainID,int subID,char *sender,char *txt,double time);

• int send_tinfo(double time,char *stxt,int severity,int mainID,int subID,char *sender,char *txt);

These routines directly send their messages :

(They bypass the message buffer and the handler and directly send via UDP broadcast.)

• int send_fatal(char *text,char *sender);

• int send_tfatal(double timx,char *text,char *sender);

• int send_urgent(char *text,char *sender);

• int send_turgent(double timx,char *text,char *sender);

The following C-functions manage the message handler task:

• start_message_hdl(int <debug>)

  This function starts the message handler as a background task with a predefined priority. If <debug> is a number not equal 0, the task will print out more messages.

• stop_message_hdl()

  This function frees the resources of the task and kills it.

The handler is a C++ class object named MessageHdl with the following public member functions:

• MessageHdl(MSG_BUFFER *msgbuf);

<msgbuf> is the address of the general Message Buffer.

• ~MessageHdl(void);

• int set(int debug=0);

  Set runtime parameters for the program. <debug> ! =0 means a printout of debug information

• int send_msg(void);

Looks continuously for new messages in the Message Buffer, compares these with those in the internal buffer and eventually sends them.

General Message Code Files (Message_IDs_???.h)

All messages send with the message sending routines should be defined in a message code file (Message_IDs_???.h). Here the general messages with their ID, severity, sender etc. and a text are defined. In that way the call to the sending routines is much easier and the messages all are well documented in that file.

Example of general and message definitions in the Message_IDs_???.h file:

#include „...message_send_doc.cpp“

/*----- Name dieses Computers aus Environment*/

extern char ThisComputer[64];

#ifndef DIESER_SENDER

#define DIESER_SENDER ThisComputer

#endif

#ifndef NO_TIME

#define NO_TIME (double)(-1.)

#endif

#ifndef NO_TEXT

#define NO_TEXT (char *)" "

#endif

/*-- Examples for messages */

#define DISPLAY_START_ID SEND_SEVERITY_INFO,1,0,DIESER_SENDER \

,(char *)" UDP-DISPLAY Handler successfully started "

#define DISPLAY_STOP_ID SEND_SEVERITY_WARN,1,1,DIESER_SENDER \

,(char *)" ***** UDP-DISPLAY Handler DELETED *****"

/* -- End of message_ID file */

A call to a message routine then has the following form:

send_info(NO_TEXT,DISPLAY_START_ID,NO_TIME);

or with an additive text, which is appended to the standard text of that message:

char text[64],

int i;

sprintf(text,“ appended message %d“,i);

send_info(text,DISPLAY_START_ID,NO_TIME);