Software Project Scheduling

• Do you believe in Magic?
  
  
• To build complex software systems..
  • many engineering tasks need to occur in parallel with one another to complete the project on time
  • the output from one task often determines when another may begin
  • it is difficult to ensure that a team is working on the most appropriate tasks without building a detailed schedule and sticking to it
    
    
    

• dealing with unrealistic schedule demands...
  1. Perform a detailed project estimate for project effort and duration using historical data.
  2. Use an incremental process model that will deliver critical functionality imposed by deadline, but delay other requested functionality.
  3. Meet with the customer and explain why the deadline is unrealistic using your estimates based on prior team performance.
  4. Offer an incremental development and delivery strategy as an alternative to increasing resources or allowing the schedule to slip beyond the deadline.
     
     
• Software Project Scheduling Principles
  
  
  
  
• Relationship Between People and Effort
  • adding people to a project after it is behind schedule often causes the schedule to slip further
  • the relationship between the number of people on a project and overall productivity is not linear
  • the Putnam-Norden-Rayleigh (PNR) Curve relates time spent with effort cost
  • note: The Software Equation was derived from this curve
    
    
    
    
• The 40-20-40 Rule (a rule of thumb)
  
  
  
  
• Getting started...
  
  
  
  
  • software project types
    • concept development - initiated to explore new business concept or new application of technology
    • new application development - new product requested by customer
    • application enhancement - major modifications to function, performance, or interfaces (observable to user)
    • application maintenance - correcting, adapting, or extending existing software (not immediately obvious to user)
    • reengineering - rebuilding all (or part) of a legacy system
      
      
  • factors affecting task set
    • size of project
    • number of potential users
    • mission criticality
    • application longevity
    • requirement stability
    • ease of customer/developer communication
    • maturity of applicable technology
    • performance constraints
    • embedded/non-embedded characteristics
    • project staffing
    • reengineering factors
      
      
• Example
  • major tasks for a concept development project
    • concept scoping - determine overall project scope
  • preliminary concept planning - establishes development team's ability to undertake the proposed work
  • technology risk assessment - evaluates the risk associated with the technology implied by the software scope
  • proof of concept - demonstrates the feasibility of the technology in the software context
  • concept implementation - concept represented in a form that can be used to sell it to the customer
  • customer reaction to concept - solicits feedback on new technology from customer
    
    
  • task refinement
    
    
    
    
• Project Scheduling
  
  
  • task networks (activity networks)
    • are graphic representations of the task interdependencies
    • can help define a rough schedule for particular project
      
      
      
      
  • Program Evaluation and Review Technique (PERT) Charts and Critical Path Method (CPM) - also called PERT/CPM
    • quantitative techniques
    • allow software planners to
      • identify the chain of dependent tasks in the project work breakdown structure
      • determine the project duration time.
  • Gantt Charts
    • enable software planners to determine what tasks will be need to be conducted at a given point in time
    • are based on estimates for effort, start time, and duration for each task
      
      
  • scheduling tools should be used to schedule any non-trivial project
    • pretty examples from SmartDraw.com (not free but you can get a 30 day evaluation)
    • Microsoft Visio can be used with Microsoft Project (widely used)
    • Google will turn up lots of products
      
      
  • Time-boxing
    • the practice of deciding a priori the fixed amount of time that can be spent on each task
    • when the task's time limit is exceeded, development moves on to the next task
    • with the hope that a majority of the critical work was completed before time ran out!
      
      
• Tracking Project Schedules
  
  
  • techniques used for tracking include
    
    • periodic status meetings
    • evaluation of results of all work product reviews
    • comparing actual milestone completion dates to scheduled dates
    • comparing actual project task start-dates to scheduled start-dates
    • informal meeting with practitioners to have them assess subjectively progress to date and future problems
    • use earned value analysis to assess progress quantitatively
      
      
  • The best indicator of progress is the completion and successful review of a defined software work product.
    • Example - Tracking Increment Progress for OO Projects
      
      

Notes and figures from:

• Software Engineering: A Practitioner's Approach, 6th Edition, by Roger S Pressman, R.S. Pressman & Associates, McGraw-Hill, 2005