The functional design process maps the "what to do" of the Requirements Specification into the "how to do it" of the design specifications. During this stage, the overall structure of the product is defined from a functional viewpoint. The functional design describes the logical system flow, data organization, system inputs and outputs, processing rules, and operational characteristics of the product from the user's point of view. The functional design is not concerned with the software or hardware that will support the operation of the product or the physical organization of the data or the programs that will accept the input data, execute the processing rules, and produce the required output.
The focus is on the functions and structure of the components that comprise the product. The goal of this stage is to define and document the functions of the product to the extent necessary to obtain the system owner and users understanding and approval and to the level of detail necessary to build the system design.
Prototyping of system functions can be helpful in communicating the design specifications to the system owner and users. Prototypes can be used to simulate one function, a module, or the entire product. Prototyping is also useful in the transition from the functional design to the system design.
Input:
The following work products provide input to this stage.
SEM Templates:
-
Maintenance Plan
-
Requirements Specification
-
Requirements Traceability Matrix
-
Software Configuration Management Plan
PMM Templates:
-
Project Plan
-
Quality Management Plan
-
Security Plan
Other Inputs:
High-Level Activities:
The remainder of this chapter is divided into sections that describe specific high-level activities performed during this stage. These activities represent the minimum requirements for a large information systems engineering effort. Notes are provided, as applicable, to assist in customizing these lifecycle stage requirements to accommodate different sizes of systems engineering efforts.
The high-level activities are presented in the sections listed below.
5.1 Determine System Structure
5.2 Design Content of System Inputs and Outputs
5.3 Design User Interface
5.4 Design System Interfaces
5.5 Design System Security Controls
5.6 Build Logical Model
5.7 Build Data Model
5.8 Develop Functional Design
5.9 Select System Architecture
Touch Points:
The following touch points are involved in the Functional Design Stage:
Contracts and Procurement
E-Michigan
Infrastructure Services
Security
-
Review MDIT and Agency security policies
-
Review
State
and Federal laws and regulations
-
Review existing or propose new security controls
-
Conduct preliminary risk analysis
-
Revise Infrastructure/Network and Data Flow Diagram
Output:
Several work products are developed during this stage. The work products listed below are the minimum requirements for a large systems project. Deviations in the context and delivery of these work products are determined by the size and complexity of a project. Explanations of the work products are provided under the applicable activities described in the remainder of this chapter.
SEM Templates:
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Functional Design Document (final)
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Maintenance Plan (revised)
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Requirements Specification (final)
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Requirements Traceability Matrix (revised)
-
Software Configuration Management Plan (revised)
PMM Templates:
-
Project Plan (revised)
-
Security Plan (revised)
Other Outputs:
Review the Project Plan for accuracy and completeness of all Functional Design Stage activities and make any changes needed to update the information.
Review Process:
Quality reviews are necessary during this stage to validate the product and associated work products. The activities that are appropriate for quality reviews are identified in this chapter and Chapter 2.0, Lifecycle Model. In addition, a Preliminary Design Review will be conducted. This review is an important milestone in the design process. The time and resources needed to conduct the walkthroughs and Functional Design Review should be reflected in the project resources, schedule, and work breakdown structure.
Structured Walkthrough (SWT)
Requirements for a peer review or a more formal structured walkthrough are documented under Review Process at the end of each Task, Subtask, or Activity section in this stage. The State of
Michigan
guide titled Structured Walkthrough Process Guide provides a procedure and sample forms that can be used for SWTs. This document is available on the MDIT SUITE website.
Stage Exit
Schedule a Stage Exit as the last activity of the Functional Design Stage to enable the project approvers to review project deliverables and provide a concur/non-concur position to the project manager. The State of
Michigan
guide titled Stage Exit Process Guide provides a procedure and sample report form that can be used for stage exits. This document is available on the MDIT SUITE website.
Complete Functional Design Stage of the SEM
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