1. Requirements

1.1 Notes

NPR 7150.2, NASA Software Engineering Requirements, does not include any notes for this requirement.

1.2 History

1.3 Applicability Across Classes

2. Rationale

To manage resource allocations and support the system development activities software projects need a detailed software schedule.

3. Guidance

The achievement of the goals and objectives of the project requires in-depth planning to develop and document and maintain an integrated set of work activities and tasks. This is normally accomplished through the use of a networked schedule. The schedule needs to include all the major activities for the project, along with its milestones and deliverables, to completely characterize all the work to be done on the project. This characterization, in turn, will allow the development of a complete listing and scheduling of needed personnel and related resources.

The software development team lead generates a software development schedule to include all activities described in the software development plan in response to the overall project/system schedule. The planned software activities need to include the detailed steps and tasks on a software schedule that meshes with the overall project schedule to assure timely and coordinated availability of the software work products for use in the overall system. Once the initial software schedule is developed and baselined, it needs to be maintained and updated to remain consistent with the overall schedule for the project.  This will eliminate overlapping demands and ensure the timely availability of project resources.

“The purpose of schedule management is to provide the framework for time-phasing, resource planning, coordination, and communicating the necessary tasks within a work effort. The intent is to improve schedule management by providing recommended concepts, processes, and techniques used within the Agency and private industry.”

The NASA Scheduling Management Handbook provides “guidance for meeting the scheduling requirements contained in NPR 7120.5, NASA Space Flight Program and Project Management Requirements

The software development lead develops a preliminary software schedule that integrates with the overall project/system schedule, noting the dates for task completion/delivery, software peer reviews/inspections, deliverables, integration/testing, hardware tests, major project reviews, project milestones, purchases, training, documentation, and other pertinent scheduling data. It typically shows the relationships and dependencies of the software work products on hardware, operations, and training needs. The lead includes activities related to other key processes, such as acquisition, metrics, configuration management, and software assurance. The lead also refines the project's software schedule based on the cost estimate and resources obtained. The software schedule is developed and maintained following the guidance provided in NASA/SP-2010-3403, NASA Schedule Management Handbook 

A Gantt chart

The software schedule can be developed and maintained using the following process steps:

Develop the schedule:

• Develop work breakdown structure (WBS) and overall network schedule.
• Define the software milestone constraints, including start date, project reviews, hardware and operations flows and dependencies, and completion dates to support the top-level project schedule.
• Review work requirements to be performed; enter task durations, resource names, and units.
• Review/adjust work requirements to be performed as necessary (to ensure a reasonable schedule).
• Include a margin or amount of slack time based on project length, team experience, or other relevant factors.
• Review/adjust resource allocations and project durations with the project team and customer as required.
• Schedule the duration (including beginning and ending dates) of various software development functions, such as requirements definition, design, coding, verification, and maintenance.
• Schedule software-specific milestones, such as software deliveries and reviews.
• The schedule needs dates and availability dates of critical dependency items.
• Show the development activities associated with components of the Computer Software Configuration Items (CSCI).
• Coordinate with disciplines and organizations that provide products/artifacts to software development, such as computer hardware, digital simulations, and dynamics algorithms.
• Coordinate with disciplines and organizations that require products/artifacts from software development.
• Establish the schedule baseline (project lead) with management approval.

Maintain the schedule:

• Report the status of the development effort to project management through status meetings.
• Report issues that impact the software development team's ability to adhere to the schedule to senior management and to project management as appropriate.
• Monitor the remaining slack or margin in the project to help identify quickly if requirement changes or schedule modifications are required.
• Resolve issues and/or revise the schedule. (Through the duration of the project, the software development team lead evaluates the impact of proposed project requirements changes and produces schedule updates that meet the approval of the project. If schedule changes are not possible, other means, such as changing or reducing requirements, can be investigated.)

The software schedule is an integral part of the overall project/system schedule and as such contributes to the critical path for the project.  The software lead must identify and understand the impact that the software development activities have on the overall integrated project schedule.  It is also important that the software leads to understanding the relationship between software development tasks and their interfaces with other project tasks. This will allow the software lead to assess changes to the project schedule that may affect software development as well as software changes that may affect the integrated project schedule. The software development team regularly evaluates the software schedule for apparent and hidden issues and risks. One means to perform these evaluations is to use the "critical path" methodology. "'Critical path'" is [characterized by determining] the sequence of dependent tasks that determines the longest duration of time needed to complete the project. These tasks drive the schedule and continually change, so they must be updated. The critical path may encompass only one task or a series of interrelated tasks."

Critical path analysis constructs a model of the project that includes the following:

• 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 be completed.
• The dependencies between the activities.

Using these values, a critical path analysis will calculate the longest path of planned activities to the end of the development activities, 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 period longer). Any delay of an activity on the critical path directly impacts the planned project/system completion date (i.e. there is no float on the critical path). A software development activity can have several, parallel, near-critical paths. An additional parallel path through the graph with the total durations shorter than the critical path is called a sub-critical or non-critical path.

These results allow managers to prioritize activities for the effective management of work product completion, and to shorten the planned critical path of a task by pruning critical path activities, by "fast-tracking" (i.e., performing more activities in parallel), and/or by "crashing the critical path" (i.e., shortening the duration of critical path activities by adding resources).

NASA-specific software schedule information and resources are available in Software Processes Across NASA (SPAN), accessible to NASA users from the SPAN tab in this Handbook. 

Additional guidance related to software project schedules may be found in the following related requirements in this Handbook:

4. Small Projects

Microsoft's Project software is frequently used to develop and track schedules.  This software is typically accessible for use on small projects.  The level of detail associated with a small project's schedule could be less than that for a larger project.  This saves small projects time in both the development and tracking of the schedule. Use a tool that is appropriate for the scale of your project. The development team may also use a Project Management Tool (like Microsoft® Project or Omniplan) to which it already has access. However, a small project of 2-3 people, or a project of less than 1 month, that may not already have access to an existing tool, may be better served by a Microsoft® Excel/Word or text-based schedule than by acquiring and being trained on using a project management tool.

5. Resources

5.1 References

5.2 Tools

6. Lessons Learned

6.1 NASA Lessons Learned

• No Lessons Learned have currently been identified for this requirement.

6.2 Other Lessons Learned

• One of the activities in the Orbital Space Plane (OSP) program required the review of a project schedule in a short time (9000 pages in 45 days). However, the lack of integration between NASA's schedule and the contractors' schedules led to a failure to foresee the consequences of accelerating the schedule. The overall finding recommends that the program should integrate both the NASA and contractor schedules and those schedules should be resource-loaded.

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• If only high-level schedule risks are considered because of the lack of an integrated continuous risk management plan, longer-term risks ("Risks beyond a short time...") to the overall schedule may not be identified and mitigated.  See the Software Program Managers Network lesson learned schedule entry under "Continuous Risk Management."

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7. Software Assurance

7.1 Tasking for Software Assurance

1. Assess that the software schedule satisfies the conditions in the requirement.

2. Develop a software assurance schedule, including software assurance products, audits, reporting, and reviews.

7.2 Software Assurance Products

• Software Assurance Plan 
• Software Assurance Plan Assessment
• Software Engineering Plans Assessment 
• A software assurance schedule including SA/Safety products and activities aligned with project activities (e.g. audits, reporting, and reviews)
• Assessment results on software schedule, including any inconsistencies, issues, or risks.

  
  

  Note
  title Objective Evidence
  Software schedule

  Expand
  title Definition of objective evidence
  Include Page SITE:Definition of Objective Evidence SITE:Definition of Objective Evidence

7.3 Metrics

• Deviations of actual schedule progress vs. planned schedule progress above-defined threshold
• # of peer reviews performed vs. # of peer reviews planned
• # of Peer Review Audits planned vs. # of Peer Review Audits performed
•  # of Compliance Audits planned vs. # of Compliance Audits performed
•  # of Open vs. Closed Audit Non-Conformances over time 
• Trends of # of Non-Conformances from audits over time (Include counts from process and standards audits and work product audits.)
• # of Non-Conformances per audit (including findings from process and compliance audits, process maturity)
• # of process Non-Conformances (e.g., activities not performed) identified by SA vs. # accepted by the project
• Trends of # Open vs. # Closed over time
• Deviations of actual schedule progress vs. planned schedule progress above-defined threshold

7.4 Guidance

Step 1 - Assess that the software schedule satisfies the following conditions:

1. 1. Coordinates with the overall project schedule. - determine if the software schedule supports the project schedule milestones and provides reasonable margins and durations for the type of software development activities.
   2. Documents the interactions of milestones and deliverables between software, hardware, operations, and the rest of the system. - determine if the software schedule supports the hardware availability, integration, and test milestones and provides reasonable margins and durations for the type of software development activities. Determine if the software schedule supports the operations milestones and provides reasonable margins and durations for the type of software development activities.
   3. Reflects the critical dependencies for software development activities - are the software engineering and software assurance products and milestones included on the schedule
   4. Identifies and accounts for dependencies with other projects and cross-program dependencies.

Step 2 - The software assurance schedule can be developed and maintained using the following process steps:

Develop the schedule:

• Define the software assurance milestone constraints, including start date, project reviews, and completion dates to support the top-level project schedule.
• Review work requirements to be performed; enter task durations, resource names, and units.
• Review/adjust work requirements to be performed as necessary (to ensure a reasonable schedule).
• Include a margin or amount of slack time based on project length, team experience, or other relevant factors.
• Review/adjust resource allocations and project durations with the project team and customer as required.
• Schedule the duration (including beginning and ending dates) of various software assurance assessment functions and audits.
• Schedule milestones, such as software assurance audits, product deliveries, assessments, and review support.
• Show the development activities.
• Coordinate with disciplines and organizations that provide products/artifacts to software assurance.
• Coordinate with disciplines and organizations that require products/artifacts from software assurance and software safety.
• Establish the schedule baseline (project lead) with management approval.

Examples of items on a Software Assurance schedule could include:

• Software Assurance plan,
• Software Assurance audit,
• Software Assurance status reports,
• Software assurance and software safety requirements mapping table for the Software Assurance and Software Safety standard requirements, the cost estimate for the project’s Software Assurance support, Software Assurance and software safety reviews and software assurance review support,
• IV&V planning and risk assessment, if required.
• The IV&V Execution Plan, if required.
• System hazard analysis assessment activities,
• Software Safety Analysis,
• Software Assurance independent static code analysis for cybersecurity vulnerabilities and weaknesses,
• Software Assurance independent static code analysis, on the source code, showing that the source code follows the defined secure coding practices,
• Software Assurance analysis performed on the detailed software requirements,
• Software assurance design analysis, SA peer reviews,
• Software Assurance metric data, reporting, and analysis activities,
• Software Assurance status reviews.

Maintain the schedule:

• Report the status of the development effort to project management through status meetings.
• Report issues that impact the software assurance team's ability to adhere to the schedule to senior management and to project management as appropriate.
• Monitor the remaining slack or margin in the project to help identify quickly if requirement changes or schedule modifications are required.
• Resolve issues and/or revise the schedule.
• Resolve any resource issues with the project.

The software schedule is an integral part of the overall project/system schedule and as such contributes to the critical path for the project.  The software assurance must identify and understand the impact that the software development activities have on the overall integrated project schedule.  It is also important that software assurance understand the relationship between software development tasks and their interfaces with other project tasks. This will allow the software assurance to assess changes to the project schedule that may affect software development as well as software changes that may affect the integrated project schedule. The software assurance team regularly evaluates the software schedule for apparent and hidden issues and risks.

Schedule path analysis constructs a model of the project that includes the following:

• 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 be completed.
• The dependencies between the activities.