Brahms - Agent Oriented Programming

Note

Brahms is a specialized agent-based programming language designed for modeling and simulating human work practices. It integrates multiple tools, including a compiler, virtual machine, and integrated development environment (IDE), to support agent development, simulation, and analysis.

Components of Brahms

The Compiler

• Purpose: Parses and compiles Brahms models (programs) into an executable format.

• Output Format: XML, compliant with Brahms Document Type Definition (DTD).

• Usage:

  bc [options] <Brahms file>

• Options:

  • -lp <library-path />: Set library path.
  • -source <source-path />: Set source code path.
  • -d <destination-path />: Set destination path.
  • -uml: Generate UML for the model.
  • -debug: Display debug information.

Tip

The compiler is integrated with the Brahms Composer to streamline development. Check the [Known Issues] before reporting bugs.

The Virtual Machine (VM)

• Purpose: Executes compiled Brahms models.

• Implementation: Written in Java, allowing Brahms agents to run as Java threads.

• Modes of Operation:

  • Simulation (sim): Runs models as simulations.
  • Real-time (rt): Executes models in real-time.
  • Distributed Real-time (drt): Supports distributed execution across multiple virtual machines.

• Usage:

  bvm [-options] [<model>]

• Options:

  • -cf <config file />: Use specified configuration file.
  • -mode (sim | rt | drt): Choose simulation mode.
  • -random_seed <n />: Seed for random number generator.
  • -time_unit <n />: Time units represented by seconds.

Note

The VM can handle distributed systems, scaling to hundreds of thousands of agents across multiple machines.

The Composer (IDE)

• Purpose: Integrated Development Environment for Brahms model design and execution.
• Features:
  • Graphical Designers: Visualize agents, objects, and interactions.
  • Source Code Editor: Syntax highlighting and error checking.
  • Package Explorer: Organizes source files and packages.
  • Task List: Displays syntax and semantic errors for quick navigation.

Tip

You can generate complete models using only graphical designers, without manually writing source code.

Agent Viewer

• Purpose: Visualizes and analyzes agent behavior and state over time.
• Key Views:
  • Runtime View: Displays agents active in the system.
  • Timeline View: Shows agent activities over time.
  • Communication View: Visualizes inter-agent communication.
  • Explanation Facility: Analyzes triggers, beliefs, and actions for deeper insight.

Note

The agent history is stored in a MySQL database and can be analyzed using SQL or Brahms’ Agent Viewer.

Brahms Agents

Defining Agents and Groups

Brahms agents are members of groups, supporting multiple inheritance. For example:

group PersonalAgent { ... }  // define group
agent JohnPersonalAgent memberof PersonalAgent { ... }  // define agent
agent Agent2 memberof PersonalAgent, AnotherGroup { ... }  // multiple inheritance

Belief-Based Agents

Unlike object-oriented languages, where objects encapsulate attributes, Brahms agents have beliefs about the attributes of agents, objects, and areas.

Example:

agent LouisArmstrong memberof Artist {
  initial_beliefs:
    (current.performs = WhatAWonderfulWorld);
    (EdithPiaf.performs = LaVieEnRose);
}

Key Concept: Beliefs are propositional sentences, allowing agents to reason based on their beliefs and make intelligent decisions.

Behavior Through Workframes

Workframes define agent actions based on preconditions. Below is an example of an agent singing a song:

group Artist {
  workframes:
    workframe SingASong {
      variables:
        foreach(Song) a_song;
      when ((current.performs = a_song) and not(current.has_performed = a_song))
      do {
        sing(a_song);
        conclude((current.has_performed = a_song));
      }
    }
}

Tip

Agents act autonomously, and workframes trigger based on the agent’s current beliefs.

Integration with Java: JAPI

• Purpose: Brahms integrates with Java through the Java Application Programming Interface (JAPI).
• Usage: Allows interaction between Brahms agents and external Java components, enabling complex, hybrid systems.

Eclipse Plugin

• Features:
  • Package management, source code editing, and compilation.
  • Integrated Agent Viewer.
• Requirements: Eclipse 3.5+ and JSE 5+.

Note

The Eclipse plugin is a lighter alternative to the Composer but lacks full design editing capabilities.

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Brahms Summary

• Brahms is a multi-component system designed for modeling, simulating, and analyzing agent-based systems.
• Agents use beliefs to reason and act autonomously.
• Brahms integrates with Java, supporting complex systems.
• The Brahms Composer and Agent Viewer streamline development and analysis.