trick/docs/documentation/simulation_capabilities/Status-Message-System.md
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HomeDocumentation HomeSimulation Capabilities → Status Message System

The Message Publisher publishes executive and/or model messages. A Message Subscriber gets the messages published by the Publisher.

Message Publisher

Trick creates one instance of the Message Publisher (in the S_define file). It is responsible for keeping track of all Message Subscribers, and sending any message that is published to all of the Message Subscribers. A subscriber is made known to the Message Publisher by calling its ::message_subscribe routine (and conversely can be removed from the publisher by calling ::message_unsubscribe). Publishing a message that you want to be output by all subscribers is done by calling ::message_publish. If there are no subscribers, then publishing a message has no effect.

Message Subscriber

There can be any number of Message Subscribers, whose job is to receive (and usually output) published messages. Trick automatically creates three Message Subscribers:

  • Trick::MessageCout - outputs messages to the standard output stream
  • Trick::MessageFile - outputs messages to a file named send_hs in the RUN directory
  • Trick::MessageTCDevice - outputs messages to a socket at port 7200, used by the Simulation Control Panel for its Status Messages display

When you publish a message, it will be output by the three subscribers above. A subscriber can be enabled / disabled at any time during simulation execution to output / ignore messages as desired. The user may also add their own subscriber by creating a derived class from Trick::MessageSubscriber.

  • Trick::MessageThreadedCout - outputs messages to the standard output stream asynchronously.

The MessageThreadedCout class is included with the simulation but not activated by default. When activated messages will be written to the standard output stream like MessageCout, but internally we use a separate thread to do the writing. This helps real-time performance.

To activate the MessageThreadedCout class, add these 2 lines to the input file.

trick_message.mtcout.init()
trick.message_subscribe(trick_message.mtcout)

User accessible routines

To publish a message:

int ::message_publish(int level, const char * format_msg, ...) ;
int ::send_hs(FILE * fp, const char * format_msg, ...) ;

The level number can be any integer from 0 to 99. Trick has a few predefined levels (Trick::MessagePublisher::MESSAGE_TYPE) that it uses for publishing messages. If the message subscriber's color is enabled (see below), then a particular colored message will be displayed for each of these levels:

  • 0 - normal message, default color
  • 1 - informational message, green
  • 2 - warning message, yellow
  • 3 - error message, red
  • 10 - debug message, cyan

To subscribe / unsubscribe Trick's default subscribers (these call ::message_subscribe / ::message_unsubscribe mentioned above):

By default these are all subscribed. You can use subscribe/unsubscribe throughout a simulation to turn on/off messages at will.

trick.message_unsubscribe(trick_message.mcout)
trick.message_unsubscribe(trick_message.mdevice)
trick.message_unsubscribe(trick_message.mfile)

To enable / disable Trick's default subscribers:

By default these are all enabled. If you disable file at startup, the send_hs file will not be created/opened. If you disable device at startup, its connection will not be established. That means you cannot then later try to enable and subscribe to file/device.

int message_cout_set_enabled(int yes_no) ;
int message_file_set_enabled(int yes_no) ;
int message_device_set_enabled(int yes_no) ;

To enable / disable showing colored messages in Trick's default subscribers:

By default color is enabled for cout and device. Color is achieved by adding ANSI escape codes around the message.

int message_cout_set_color(int yes_no) ;
int message_file_set_color(int yes_no) ;
int message_device_set_color(int yes_no) ;

Continue to Command Line Arguments