diff --git a/lib/util.rb b/lib/util.rb
new file mode 100644
index 0000000..8b3a8cc
--- /dev/null
+++ b/lib/util.rb
@@ -0,0 +1,183 @@
+
+
+class IdGenerator
+
+	def initialize
+		@id_char = ['0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F','G','H','I','J','K','L','M','N','O',
+		'P','Q','R','S','T','U','V','W','X','Y','Z', '0', '1', '2', '3', '4']
+		@length = @id_char.length
+		@id_char_num = ['0','1','2','3','4','5','6','7','8','9']
+		
+	end 
+	
+	def generate(length)
+		id = ''
+		1.upto length do 
+			id << @id_char[rand(@length)]
+		end
+		return id
+	end
+	
+	def genAndStore(count, length)
+		@ids = []
+		1.upto count do
+			@ids << generate(length)
+		end
+	end
+
+	def generateNum(length)
+		id = ''
+		1.upto length do 
+			id << @id_char_num[rand(@id_char_num.length)]
+		end
+		return id
+	end
+	
+	def genAndStoreNum(count, length)
+		@ids = []
+		1.upto count do
+			@ids << generateNum(length)
+		end
+	end
+
+	def sample
+		@ids[rand(@ids.size)]
+	end
+
+end
+
+class NameGenerator
+
+	def initialize
+		@name_char = ['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s',
+			't','u','v','w','x','y','z']
+		@length = @name_char.length
+	end 
+	
+	def generate(length)
+		name = ''
+		1.upto length do 
+			name << @name_char[rand(@length)]
+		end
+		return name
+	end
+	
+	def genAndStore(count, *lengths)
+		@names = []
+		1.upto count do
+			@names << generate(lengths[rand(lengths.size)])
+		end
+	end
+	
+	def sample
+		@names[rand(@names.size)]
+	end
+
+end
+
+class EvenGenerator
+	def addEvent(event, *prob)
+		@events[event] = prob
+	end
+	
+	def generate
+		evtGen = {}
+		
+		#independent
+		@events.each do |k, v|
+			if (v.length == 1)
+				evtGen[k] = v[0] < rand(100)
+			end
+		end
+		
+		#conditional
+		@events.each do |k, v|
+			if (v.length > 1)
+				condEvt = v[1]
+				if (evtGen[condEvt])
+					evtGen[k] = v[2] < rand(100)
+				else 
+					evtGen[k] = v[0] < rand(100)
+				end
+			end
+		end
+		
+	end
+	
+end
+
+class IdField
+	def initialize(length, idGen)
+		@length = length
+		@idGen = idGen
+	end
+	
+	def value
+		@idGen.generate(@length)
+	end
+	
+end
+
+class CategoricalField
+
+	def initialize(*args)
+		@dist = []
+		values = args.size == 1 ? args[0] : args
+		i = 0;
+		while (i < values.length)
+			val = values[i]
+			count = values[i + 1]
+			1.upto count do
+				@dist << val
+			end
+			i = i + 2
+		end
+	end
+
+	def value 
+		@dist[rand(@dist.length)]
+	end
+	
+end
+
+class NumericalField
+	def initialize(uniform, *args)
+		@uniform = uniform
+		@dist = []
+		
+		if (uniform)
+			@min = args[0]
+			@max = args[1]
+		else 
+			values = args.size == 1 ? args[0] : args
+			i = 0;
+			while (i < values.length)
+				val = values[i]
+				count = values[i + 1]
+				
+				j = 0
+				done = false
+				while (!done)
+					val.each do |v|
+						@dist << v
+						j = j + 1
+						if (j == count) 
+							done = true
+							break
+						end
+					end
+				end
+				i = i + 2
+			end
+		end
+	end
+
+	def value 
+		if (@uniform)
+			@min + rand(@max - @min)
+		else 
+			@dist[rand(@dist.length)]
+		end
+	end
+end
+