http://www.rubyagent.com Ruby on Blackboard Wed, 09 Apr 2008 22:02:06 +0000 http://backend.userland.com/rss092 en One of the main principles of agent-oriented modeling is agent's proactivness - living and acting continuously on its own. Technically, this means that the piece of code is running in a kind of loop receiving messages, acting upon them and sending out other messages. This is the heartbeat of each ... http://www.rubyagent.com/2008/02/scheduling-of-ruby-agents-using-cron/ I would like to welcome a new author, a good friend of mine, Ruby and agent-based systems fan: Viktor Zigo (viz). His first post will be about scheduling agents. Welcome :) http://www.rubyagent.com/2008/02/new-author/ Problem: An agent should consider a shutdown flag presence. Solution: The solution is to use a modified Boolean Flag Pattern, where the flag specific operation is to break the loop for reading an n-tuple, i.e. the Agent Life Cycle pattern. (life cycle, boolean flag and shutdown flag patterns) loop do begin ... http://www.rubyagent.com/2007/12/pattern-shutdown-flag/ Problem: An agent should consider a flag presence. Solution: The solution is to set a timeout for a read or take operation, where the timeout value specifies how often a flag appearance should be checked, and if the flag is presented to perform the flag specific operation. The Agent Life Cycle pattern ... http://www.rubyagent.com/2007/12/pattern-boolean-flag/ Problem: An agent should be able to check the blackboard for an n-tuple and to process the obtained n-tuple. (It is a trivial pattern.) Solution: The solution is to perform operation read or take in a loop. loop do read or take n-tuple process n-tuple end Example: loop do t = ts.take ... http://www.rubyagent.com/2007/12/pattern-agent-life-cycle/ Operations that access a blackboard to retrieve information, i.e. operations read and take, have a second parameter that defines how long should this operation wait until there will be a matching n-tuple or, simply, timeout. A value of the parameter specifies number of second. Example: To read a tuple and if there ... http://www.rubyagent.com/2007/12/access-blackborad-with-timeout/ Now, we have enough knowledge to create a simple example: a calculator. The example shows how to: Create an agent. Locate the blackboard. Write a tuple (a calculator operation). Take a tuple (a calculator operation result). Differentiate between different operations (plus and minus). Handle a simple ID. The calculator agent will be able to handle two kinds of ... http://www.rubyagent.com/2007/05/simple-example-calculator-agent/ To finish the overview of the backboard operations, let's show how to use the read operation. It only checks, if a blackboard contains a wanted tuple (in the previous posts I used the term message, but now we are more experienced :). The following functionalities will be shown: Creation of an agent. Locating ... http://www.rubyagent.com/2007/05/read-message-on-blackboard/ In the last posts a term message was used. In the Rinda documentation you would not probably find this term; it is called more accurately: tuple. What is a tuple? [1, 2] is a tuple [:message, 'Hi there!'] is a tuple ['Hi there!', :message] is also a tuple [:result, 42, 'John', 'Susanne', 'London'] is a ... http://www.rubyagent.com/2007/04/message-and-tuple/ The Rinda multi-agent system environment is already running, on the blackboard is written a message, so the last step is to read it :) The following functionalities will be shown: Creation of an agent. Locating the blackboard. Taking a message. Although a logical opposite operation to the write operation should be the read operation, it ... http://www.rubyagent.com/2007/03/take-message-from-blackboard/