1. Installation plan
Tomas Drencak

2. The problem
● Create installation plan for customer
requesting Cable TV with Internet
● Order contains:
– Technology (optic, regular)
– TV/Internet/Phone
– Address
– Etc...

3. The solution
● Backward composition of directed acyclic
graph
● Root node is customer order
● Each other node is installation instruction
● Edge means that parent can't be executed
before child

4. Example #1
Order
DSL
entry point
Configure
DSL modem
Wire
Segment 1
Wire
Segment 2

5. Composition
● Backward composition
● Each node is of certain type and can connect
to only certain nodes
● Nodes types are stored in DB
● Evaluate which nodes can connect to the node
● Node instances are instantiated from node
types in runtime

6. Example #2
● Algorithm:
Incomplete = [order_node]
While not incomplete.is_empty():
for node in incomplete:
node_types = db.find_suitable_node_types(node)
For child_type in node_types:
If child_type.can_expand(node):
child_node = child_type.expand(node)
Incomplete.add(child_node)
If node.is_complete():
Incomplete.remove(node)

7. Database
parent_type type Condition
Order DslEntryPoint Parent.technology == 'DSL'
DslEntryPoint OpticFibre parent.technology == 'DSL' &&
parent.order.medium = 'optic'
DslEntryPoint Modem
Configuration
Parent.technology == 'DSL' &&
Exists('OpticFibre', 'EntryPoint')

8. Example of node
class DslEntryPoint:
def can_expand(node):
return evaluate(this.condition, parent=node)
def expand(parent):
child = new DslEntryPoint(parent.address)
parent.add_child(child)
return child

9. Graph prunning

10. Summary
● Backward graph composition
● Graph prunning (inverse)
● Condition evaluation
● Polymorphism/interfaces

11. Thank you!
Any questions?