Systems Development Lifecycle (SDLC)

The SDLC is a mechanism assuring that systems meet established requirements and further the organization's business strategic goals. It provides a structured approach to managing projects, beginning with the justification for initiating development or maintenance efforts and concluding with system disposal.

Most organizations spend millions of dollars annually in the acquisition, design, development, implementation, and maintenance of information systems. The need for secure and reliable system solutions is easily recognized by the dependence on computer systems needed to provide products and administer daily activities.

SDLC methodology establishes policies, procedures, and guidelines managing project development, planning, requirements analysis, design, development, integration and test, implementation, and operations, maintenance, and disposition of information systems. The SDLC is not the do-all, be-all, end-all methodology. There are many permutations of it, but those concepts will not be addressed in this section. However, SDLC is one development method that has a proven track record and should be integrated with already-existing organization policies and procedures.

SDLC Benefits
- Reduced risk of project failure

- Consideration of user requirements throughout the system's lifetime

- Early identification of technical, performance, and management issues

- Description and disclosure of all costs guiding business decisions

- Realistic user expectations of what the system will deliver

- Identification of systems and processes that are no longer cost effective

- Measurements of project progress to enable necessary corrections

- Supports effective resource and budget planning and accountability

- Identifies current and future business requirements

SDLC Supports the Use of an Integrated Product Team
The SDLC project team can provide for the project's success. It should be an interdisciplinary group composed of a senior management project sponsor, a project manager, and team members responsible for planning, implementation, and delivery. Team members should comprise senior employees representing business units such as user groups, human resources, program/functional management, quality assurance, security, legal, telecommunications, data administration, database administration, logistics, financial, systems engineering, test and evaluation, contracts management, audit, physical facilities, and configuration management. Working together in a proactive, open-communication, team-oriented environment can build a successful project by providing decision makers with the necessary experience and information to make the right decisions at the right time.

The SDLC has nine phases or steps that will be briefly described:

SDLC System Concept Development Phase. This project concept initiates the development lifecycle. It begins when a business need, based on operational requirements, is identified. Once the operational requirement is expressed, the approaches for meeting it are reviewed for necessity, feasibility, reasonableness, and appropriateness. The need may involve development of a new product or the modification of an existing system. Senior managers are usually the responsible officials for approvals and funding before the planning phase can begin.

Planning Phase. A program plan is developed documenting the approach to be used, including the formulation of methods, tools, resources, schedules, user input, funding, audit, and risk management.

Requirements Analysis Phase. User requirements are formally defined along with the requirements of system performance, data, risk management, and maintenance. All requirements are detailed to such a level that it is sufficient for designers to proceed.

Design Phase. The external characteristics of the system are designed during this phase. Operating environments are established, major sub-systems with their required inputs and outputs are defined. At this time, processes are allocated to resources. User input is documented, reviewed, and modified, and final approval is made. Internal characteristics of the system are described, specified, and designed. Required logic specifications are prepared for software modules.

Development Phase. Detailed specifications produced during the design phase are translated into hardware, software, and communications links. Software is integrated, tested, modified if necessary, and retested.

Integration and Test Phase. System integration, risk management, and user acceptance are conducted during this phase. Users, audit, and quality assurance units validate the functional requirements, as defined in the functional requirements documentation. It is important that these functional requirements are satisfied by the developed system.

Implementation Phase. The systems are installed and made operational initially in a test environment. After successful testing, the system is made operational in a production environment. This phase continues until the system is operating in production in conformity with user requirements and design parameters. Its security is certified. In this phase, it is accepted or rejected by users.

Operations and Maintenance Phase. By now the system is operating and is monitored for continued performance, satisfying user requirements. If needed, system modifications proceed through a requirements and necessity phase; they are scheduled, designed, tested, and implemented. If more than relatively simple modifications or changes are identified, the system will reenter the planning phase.

Disposition Phase. Disposition activities ensure the orderly review, modification, and termination of the system. Emphasis is granted to the preservation of data processed by the system in order for data to be migrated to another system or stored in compliance with records management policies, laws, or regulations for future accessing and processing.

Management Controls
The SDLC requires the following comprehensive management controls:

- Structured approach to systems development, operation, and disposal

- A senior management sponsor, preferably someone with a cheerleader's enthusiasm

- Project management limited to a single, accountable project manager

- Comprehensive project planning required for each system project

- Projects proceed when sufficient resource availability is assured

- Organized and accessible documentation of all steps, decisions, deliberations, agreements, requirements, plans, proposals, schedules, risk management, security measures, quality controls, funding, auditing, and meetings

Documentation
The SDLC specifies that documentation shall be generated during each phase. The principal categories of documentation are divided into two types:

Process documentation details actions taken for developing, implementing, testing, and maintaining the system. Process documentation includes but is not necessarily limited to plans, notes, meeting minutes, deliberations, funding, schedules, charts, funding expenditures, auditing documents, quality control decisions, reports, and time and attendance reports.

Product documentation includes matters that detail the system itself, what it is, how it is operated, how it is maintained, and future disposal. Examples include but are not limited to technical manuals, user manuals, operations manuals, maintenance manuals, systems requirements documentation, and design documentation.

It should be noted that some documentation will remain relatively static throughout the system lifecycle and some will be continuously changed. Some documents are revised documenting the results of analyses performed during operations. Each document should be collected, stored securely, and protected for future reference. It is important that regulatory and legal issues are addressed before any documentation is destroyed. Undocumented or inadequate documentation of decisions and events can cause significant confusion or wasted efforts and can intensify the effect of team member turnover. Activities should not be considered complete, nor decisions made, until there is sufficient documentation of the activity or decision. In the case of some very large projects, there cannot be advancement to the next SDLC phase without the required audits, management reviews, and appropriate approvals.

System Accreditation and Certification
The accreditation process in the SDLC ensures that the system will operate within an acceptable threshold of risk, and complies with the system security policies and any legal and regulatory requirements. At the completion of each lifecycle phase, the accreditation manager (usually the senior manager responsible for accepting the system) reviews the certification results in the design documentation to determine if the system design should proceed to the next lifecycle phase or if the design should be altered to reduce risks. The decision to halt or progress will depend on the acceptability of identified risks and compliance of the system's design to the applicable policies.

System accreditation is the process forcing managers and technical staff to find the best risk management processes, given the system's technical structure, operational constraints, and business requirements. By completing the system accreditation process, the senior managers accept the risks associated with the system.

The role of certification in the SDLC is similar to the role of system quality assurance in that the certification process validates, verifies, and tests the system's features. Certification evaluates the system to determine whether the system operates according to the requirements and does not deliver new functionality introducing new risks. Certification includes total system performance and security policy compliance in security validation, security verification, security testing and evaluation, and system risk assessments. In addition to determining the system's compliance to security and policy requirements, the certification process must ensure the system complies with technical and regulatory requirements. It is important that applicable policies and safeguards are identified as early as possible in the SDLC.

Security officers, auditors, quality control employees, and management responsible for accreditation have security responsibilities. Security officials are closer to the day-to-day operation of the system and direct, perform, and monitor security tasks. The general system manager will have responsibility for the organization supported by the system. Accreditation is not a decision that should be made by the security office, rather it is the duty of the business manager to accept the system along with its associated risks. Formalization of the system accreditation process reduces the potential that systems will be placed into a production environment without appropriate management review.

Management acceptance of the system must be based on an assessment of management, operational, and technical controls. Because the security plan establishes the system protection requirements and documents the security controls in the system, it should form the basis for the system's accreditation. System accreditation is usually supported by a technical or security evaluation (or both), risk assessment, contingency plan, audit, and acknowledged policies of acceptable user behavior.

Reaccreditation should occur after any significant system change and at least every two to three years. If there is a high degree of risk, it should be performed more often. Following are the minimum security controls that must be in place prior to accrediting a system to begin processing. These principles should be made part of policies regarding systems development.

The level of controls should be consistent with the level of data or system sensitivity

- Technical and security evaluation complete

- Risk assessment conducted

- Policies of acceptable behavior established and acknowledged by users

- Disaster recovery and business resumption plans developed and tested

- System survivability and security plan developed, updated, and reviewed

- System meets all applicable laws, regulations, policies, and operations standards

- Safeguards operating as intended

- Auditing processes developed and implemented