Critical Path

Critical Path Method for Projects in OpenERP 7

The critical path method (CPM) is an algorithm for scheduling a set of project activities. It is an important tool for effective project management.

In OpenERP 7, once the user has installed our new modules, she performs the following steps:

  • A list of all activities required to complete the project (typically categorized within a work breakdown structure),
  • The time (duration) that each activity will take to complete.
  • The dependencies between the activities and,
  • Logical end points such as milestones or deliverable items.

Let’s start with this example:

Phase Task id Duration (hours) Predecessor Earliest start Latest finish
Proposal Evaluate the type of proposal and additional requirements. A 16   01/01/14  
Proposal Create proposal document B 8 A    
Proposal Milestone: Proposal finalized C 0 B    
Proposal Review and approve proposal D 32 C    
Proposal Milestone: Proposal approved E 0 D    
Cost analysis Identify costing elements F 8 A    
Cost analyisis Quantify costs for element A G 8 F    
Cost analysis Quantify costs for element B H 8 F    
Cost analysis Quantify costs for element C I 8 F    
Cost analysis Milestones: Cost analysis delivered J 0 G,H,I    
Delivery Design  K 40 J    
Delivery Realization  L 48 J    
Delivery Testing M 32 J    
Delivery Review work N 32 K,L,M    
Delivery Presentation to customer O 8 N    
Delivery Milestone: Customer acceptance P 0 O   31/01/14
Delivery Release to production environment Q 8 P    
Delivery Invoice to customer R 8 Q    
Delivery Milestone: Customer collections finalized  S 0 R    


The network representation of the ativities would be:openerp_eficent_activity_scheduling_network

See how in OpenERP 7 the tasks can be linked to each other:



The user can insert time constraints (limitations) and durations on each activity, and indicate if it’s a milestone:openerp_eficent_activity_scheduling_6

Once the user initiates the scheduling the dates of the activities are automatically calculated:openerp_eficent_activity_scheduling_8

CPM calculates the longest path of planned activities to logical end points or to the end of the project, and the earliest and latest that each activity can start and finish without making the project longer. This process determines which activities are “critical” (i.e., on the longest path) and which have “total float” (i.e., can be delayed without making the project longer).


The Gantt representation of the activities now indicates the organization of the project activities:openerp_eficent_activity_scheduling_7