Precedence

Summary

Precedence is an API that allows for the creation and analysis of precedence networks, a tool used in project management.

Version

1.0

Installation

Precedence is available as a Ruby gem. The latest release can be found at http://www.aimred.com/gems/precedence-1.0.gem

Source can also be downloaded from it’s Subversion repository at http://precedence.googlecode.com/svn/

Example Usage

Set up network

 net = Precedence::Network.new('Begin','End')
 net.new_activity('act-1-1') do |act|
         act.duration = 3
         act.description = 'System specification'
 end
 net.new_activity('act-1-2' do |act|
         act.duratiom = 2
         act.description = 'Review'
 end
 net.new_activity('act-1-3') do |act|
         act.duration = 2
         act.description = 'System re-specification'
 end
 net.new_activity('act-2-1') do |act|
         act.duration = 3
         act.description = 'Test tool design'
 end
 net.new_activity('act-2-2') do |act| 
         act.duration = 5
         act.description = 'Test tool implementation'
 end
 net.new_activity('act-3-1') do |act|
         act.duration = 3
         act.description = 'System design'
 end
 net.new_activity('act-3-2') do |act|
         act.duration = 12
         act.description = 'System implementation'
 end
 net.new_activity('act-2-3') do |act| 
         act.duration = 10
         act.description = 'System testing'
 end
 net.connect('act-1-1','act-1-2')
 net.connect('act-1-2','act-1-3')
 net.connect('act-1-3','act-3-1')
 net.connect('act-1-2','act-2-1')
 net.connect('act-2-1','act-2-2')
 net.connect('act-2-2','act-3-2')
 net.connect('act-3-1','act-3-2')
 net.connect('act-3-2','act-2-3')
 net.fix_connections!

Generate a diagram

 File.open('network.dot',File::CREAT|File::TRUNC|File::WRONLY) do |file|
        file.puts(net.to_dot)
 end
 system("dot","-Tpng","-onetwork.png","network.dot")

Perform some analysis of the activities

 activity = net.activities['act-1-2']
 activity.on_critical_path? # => true 
 activity.earliest_start # => 3.0
 activity.latest_finish # => 5.0
 activity.total_float  # => 0 - activities on the critical path have no float

Save the network to a YAML file

 File.open('network.yaml',File::CREAT|File::TRUNC|File::WRONLY do |file|
         file.puts(net.to_yaml)
 end

Read the network from a YAML file

 new_net = Precedence::Network.from_yaml(File.new('network.yaml',File::RDONLY))

License

This software is made available under the BSD license.