STEP 4. PRELIMINARY DESIGN DOCUMENT (PDD)
Table of Contents
PRELIMINARY DESIGN DOCUMENT (PDD) INSTRUCTIONS
Enter the name of the project.
The preliminary design document is developed in conjunction with the requirement analysis process to communicate the hardware and software components necessary to satisfy user requirements.
Identify sources of information used to develop this document. Include documents that define and trace system requirements; e.g., Feasibility Assessment or Requirements.
List dependencies or limitations that may affect the design of the software. Examples include budget and schedule constraints, staffing issues, availability of components, etc. Describe how each factor will affect the functional design.
3.1 Software/Hardware Design
Decompose the system software/hardware into design entities or objects that interact with and transform data to perform the required system objectives. Assign a unique name to each design entity and group entities by type; e.g., class, object, and procedure. Describe how each design entity satisfies system requirements. In user terminology, specify the inputs, outputs, and transformation rules for each design entity. Depict how design entities depend on one another.
3.2 Data Design and Control
Identify specific data elements and logical data groupings stored and processed by the design entities in 3.1 above. Outline data dependencies, relationships and integrity rules in a data dictionary. Specify the format and attributes of all data elements or data groupings.
3.3 Computer/User Interface Design
Describe the user interface and the software operating environment including the menu hierarchy, data entry screens, display screens, online help and system messages. Specify where in this environment the necessary inputs are made and list the methods of data outputs; e.g., printer, screen, and file. Note any design standards applied. If project human-machine interface design standards have been developed, discuss them in this section.
3.4 System Interface Design
Specify how the software product will interface with other systems. For each interface, describe the inputs and outputs for the interacting systems. Explain how data is formatted for transmission and validated upon arrival. Note the frequency of data exchange.
3.5 Security Design
List any access restrictions for the various types of system users. Describe any access code systems used in the software. Identify any safeguards protecting the system and its data. Specify communications security requirements.
For each numbered system requirement, identify the section(s) of this document that specify how the PDD will meet the requirement.
Include an appropriate SC concurrence/approval section.
Provide a glossary of all technical terminology used with the document.
Use appendices to document any specific alternative vendor information.