ISDP2: System design and implementation- DEVELOPMENT PHASE UNIT 2

1.0 INTRODUCTION The objective of the Development Phase will be to convert the deliverables of the Design Phase into a complete information system. Although much of the activities in the Development Phase address the computer programs that make up the system, this phase also puts in place the hardware, software, and communications environment for the system and other important elements of the overall system. 2.0 OBJECTIVES By the end of this unit, you should be able to: • Acquire enough skills to perform software requirements analysis • List the various stages of system architectural design • Enumerate the stages of systems requirement analysis
  • Overview

 

The activities of this phase translate the system design produced in the Design Phase into a working information system capable of addressing the information system requirements. The development phase contains activities for requirements analysis, design, coding, integration, testing, and installation and acceptance related to software products. At the end of this phase, the system will be ready for the activities of the Integration and Test Phase.

 

  • Tasks and Activities

 

These activities consist of several tasks that are the responsibility of the developer. The developer shall place the outputs under the Configuration Management Process and perform change control in accordance with it. The developer shall also document and resolve problems and non conformance found in the software products and tasks.

 

The developer shall select, tailor, and use those standards, methods, tools, and computer programming languages that are documented, appropriate, and established by the organization for performing the activities of the Development Process.

 

Plans for conducting the activities of the development phase should be developed, documented and executed. The plans should include specific standards, methods, tools, actions, and responsibility associated with the development and qualification of all requirements including safety and security. Separate plans may be developed. The detailed project Work Breakdown Structure (WBS) developed during the Planning Phase should be expanded to incorporate the WBS structure into each module or software configuration item to be developed.

 

  • System Requirements Analysis

 

  • Analyze the intended use of the system to be developed to specify the system requirements. The system requirements specification shall describe the functions and capabilities of the system; the business, organizational and user requirements, the safety, security,

 

human-factors engineering (ergonomics), interface, operations, and maintenance requirements; the design constraints and qualification requirements. The system requirements specification shall be documented.

 

  • Evaluate the system requirements using the criteria listed below. The results of evaluations shall be documented.

 

  • traceability to acquisition needs
  • consistency with acquisition needs

 

  • testability

 

  • feasibility of system architectural design

 

  • feasibility of operation and maintenance

 

  • System Architectural Design

 

  • Establish a top-level architecture of the system and document it. The

architecture shall identify items of hardware, software, and manual -operations. All the system requirements should be allocated among the hardware configuration items, software configuration items, and manual operations.

 

  • Evaluate the system architecture and the requirements for the above items using the criteria listed below. Document the results.

 

  • traceability to the system requirements
  • consistency with the system requirements

 

  • appropriateness of design standards and methods used

 

  • feasibility of the software items fulfilling their allocated

requirements

 

  • feasibility of operation and maintenance

 

  • Software Requirements Analysis

 

Establish and document software requirements, including the quality characteristics specifications described below.

 

  • functional and capability specifications, including performance, physical characteristics, and environmental conditions under which the software item is to perform;

 

  • interfaces external to the software item;

 

  • qualification requirements

 

 

  • safety specifications, including those related to methods of operation and maintenance, environmental influences, and personnel injury;

 

  • security specifications, including those related to compromise of sensitive information;

 

  • human-factors engineering (ergonomics), including those related to manual operations, human-equipment interactions, constraints on personnel, and areas needed concentrated human attention, that are sensitive to human errors and training;

 

  • data definition and database requirements;

 

  • installation and acceptance requirements of the delivered software product at the operation and maintenance site(s);

 

  • user documentation

 

  • user operation and execution requirements

 

  • user maintenance requirements

 

  • Evaluate the software requirements using the criteria listed below and document them.

 

  • traceability to system requirements and system design
  • external consistence with system requirements

 

  • internal consistency

 

  • testability

 

  • feasibility of software design

 

  • feasibility of operation and maintenance

 

  • Conduct joint reviews. Joint reviews are at both project management and technical levels and are held throughout the life of the contract.

 

This process may be employed by any two parties, where one party (reviewing party) reviews another party (reviewed party).

 

  • Software Architectural Design

 

  • Transforms the requirements for the software item into an architecture that describes its top-level structure and identifies the software components.

 

 

  • Ensures that all the requirements for the software item are allocated to its software components and further refined to facilitate detailed design.
  • Develop and document a top-level design for the interfaces external o the software item and between the software components of he software item.

 

  • Develop and document a top-level design for the database.

 

  • Develop and document preliminary versions of user documentation.

 

  • Define and document preliminary test requirements and the schedule for Software Integration.

 

  • Evaluate the architecture of the software item and the interface and database designs using the criteria listed below.

 

  1. traceability to the requirements of the software item
  2. external consistency with the requirements of the software item
  3. internal consistency between the software components;
  4. appropriateness of design methods and standards used
  5. feasibility of detailed design
  6. feasibility of operation and maintenance
  7. Conduct joint reviews. Joint reviews are at both project management and technical levels and are held throughout the life of the contract. This process may be employed by any two parties, where one party (reviewing party) reviews another party (reviewed party).

 

 

  • Software Detailed Design.

 

  • Develop a detailed design for each software component of the software item. The software components shall be refined into lower levels containing software units that can be coded, compiled, and tested. Ensure that all the software requirements are allocated from the software components to software units.

 

  • Develop and document a detailed design for the database.
  • Develop and document a detailed design for the interfaces external to the software item, between the software components, and between the software units. The detailed design of the interfaces shall permit coding without the need for further information.
  • Update user documentation as necessary.
  • Define and document test requirements and schedule for testing software units. The test requirements should include stressing the software unit at the limits of its requirements.
  • Update the test requirements and the schedule for Software Integration.
  • Evaluate the software detailed design and test requirements considering the criteria listed below:
    • traceability to the requirements of the software item
    • external consistence with architectural design
    • internal consistency between software components and software units
    • appropriateness of design methods and standards used
    • feasibility of testing
    • feasibility of operation and maintenance
    • Conduct joint reviews. Joint reviews are at both project management and technical levels and are held throughout the life of the contract. This process may be employed by any two parties, where one party (reviewing party) reviews another party (reviewed party).

 

  • Software Coding and Testing.
  • Develop and document each software unit and database as well as test procedures and data for testing each software unit and database.
  • Test each software unit and database ensuring that it satisfies its requirements. Document the results.
  • Update the user documentation as necessary.
  • Update the test requirements and the schedule for Software Integration.
  • Evaluate software code and test results considering the criteria listed below:
  • traceability to the requirements and design of the software item
  • external consistency with the requirements and design of the software item
  • internal consistency between unit requirements
  • test coverage of units
  • appropriateness of coding methods and standards used
  • feasibility of software integration and testing
  • feasibility of operation and maintenance

CONCLUSION

The systems development phase is made of up a series of stages. These must be accomplished sequentially, if a successful development of an information system is to be conducted for any organization.y

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