What the Systems Development Life Cycle (SDLC)?

The systems development life cycle (SDLC) is defined as the methodology and process to develop and implement a software application.   Also, the systems development life cycle concept is commonly used for different hardware and software configurations.

There are usually seven (7) phases of the systems development life cycle SDLC: Planning, System Analysis & Requirements, System Design, Development, Integration and Testing, Implementation, Operation, and Maintenance.

SYSTEMS DEVELOPMENT LIFE CYCLE SDLC SUMMARY

Phase 1. Planning

The purpose of the planning stage is to make a feasibility study to find out the scope of the problem and determine the best solution(s). In some cases, it may include a study of necessity, change control, project plan, and validation plan considering the resources, costs, time, benefits, and other items.

Phase 2. System Analysis and Requirements

This stage considers the creation of the system configuration and functional requirements specifications (FRS) of all different solution(s), application(s), or alternative(s) either hardware or software.   It’s also considered the system analysis of the end user’s needs, called user requirement specifications (URS) to ensure that the solution(s) can meet their expectations.  A request for quotation (RFQ) is typically solicited to all different vendors or developers available to build the potential application solution(s).

Phase 3. System Design

Once all different proposals and quotations are received from vendors and suppliers, they shall be evaluated with their pros and cons.  In this stage, the desired RFQ product system design is chosen and selected based on price, features, and operations as described in detail, including screen layouts, business rules, process diagrams, pseudocode, and other documentation. Besides, this stage may include the preparation of the traceability matrix document to make sure that all user’s requirements specifications match the functional requirements specifications.  Finally, the decision to obtain and buy the solution is taken at this moment. Typically, a requisition and purchase order is formally placed to the selected vendor to pay for the solution or to create it.

Phase 4. Development

In this phase, the solution (hardware or software) shall be received and installed as planned. (in case it is an off-the-shelve)

Otherwise, if the solution is not an (off-the-shelve already built), then, here start the process to write the code and create the solution either software or hardware.

At this moment is when programmers, network engineers, or database developers are working on doing the major work on the creation and installation in the development environment. Their work may include flow charts to ensure that the process of the system is properly organized and done as planned and described in the approved User Requirement Specifications and Functional Requirement Specifications.

Phase 5. Integration and Testing

In this phase, the application solution is verified and validated by the Quality Department (or a third party entity independent of the developers) to confirm that the installation and integration are tested.

It must meet the established and approved URS User Requirement Specifications and Functional Requirement Specifications.

Testing may be repeated several times at the worst-case conditions or stress scenarios, specifically to check for errors, bugs, and interoperability until the end-user finds it acceptable in the quality/testing environment.  The following diagram shows how the:

(1) System Configuration is verified in the Installation Qualification (IQ),

(2) Functional Requirement Specifications (FRS) are verified in the Operational Qualification (OQ) and

(3) User Requirement Specifications (URS) are verified in the Performance Qualification (PQ).

Testing Types

The application is tested at various levels in software testing.

The following are types of testing that may be relevant, depending on the type of system under development:

Defect testing the failed scenarios, including

• Path testing
• Data set testing
• Unit testing
• System testing
• Integration testing
• Black-box testing
• White-box testing
• Regression testing
• Automation testing
• User acceptance testing
• Software performance testing

Once the verification and validation activities are completed, the following documents can be generated and approved:

1. Traceability Matrix Updated.
2. Validation Report.
3. Procedures and Training
4. Change Control Closure Report.

Phase 6. Implementation

The sixth phase is when the program is written, installed, and validated. Additionally, this phase involves the actual installation of the newly-developed system into the production environment to start the go-live process with the end-users. This step puts the application into real operation by moving the data and components from the old system and placing them in the new system via a planned direct cutover.

Phase 7. Operations and Maintenance

This final phase involves maintenance and regular required updates. This step is when the change control management system takes control of any improvement or modification into the system to keep it in the validation state.  Also, in this phase, all applicable procedures and training must be completed and finally approved.  In addition, the audit trail system shall be monitoring and documenting any change into the system to keep tracking of its performance and use.

Importance of the SDLC

It is called the “life cycle” because if the company needs to change or improve the application system, then the company must start in Phase 1 Planning and pass through each phase again.