SDLC

I recommend that you follow a more traditional systems development life-cycle model (SDLC) when developing a comprehensive SAS macro-based reporting system. Unlike much of the one-time-only SAS programming that occurs for a clinical trial, you need to ensure that a general-purpose SAS macro system is robust enough to handle any problem it encounters. The systems development life-cycle approach to software development will help you to build strong software applications with SAS. 

If you plan to get into serious applications development, or even if you plan to write comprehensive generic SAS macros, you will want to learn about the systems development life cycle (SDLC). Developed by the Institute of Electrical and Electronics Engineers (IEEE), the SDLC has been the traditional approach to software applications development for a long time. Besides the traditional SDLC, there are many derivative... 

Most of the instruments used in the laboratory are commercial off-the-shelf (COTS) instruments, and consequently the users have little or no input into their design. A full system development life-cycle (SDLC) approach [8], which is used to develop complex computerized systems such as Laboratory Information Management System (LIMS) or Chromatographic Data System (CDS) or custom design laboratory equipment, is not appropriate for COTS instruments. Some laboratory instruments such as a pH meter or centrifuge are fairly simple and therefore do not warrant the SDLC approach. 

Changes are proposed, documented, requested, evaluated, approved, and tested prior to implementation. The quality unit should be responsible for managing both the entire process and all corresponding documentation associated with the change. Change control typically begins at an SDLC milestone defined in a project validation plan. The CRS should at least be fully designed, documented, validatable, and implementable. 

FIGURE 20.6 A System Development Life Cycle (SDLC) of a Chromatography Data System. 

It is useful to understand the steps of the software development life cycle (SDLC) during a project. In fact, this approach is commonly used for implementation and validation even when commercial off-the-shelf software is involved [104]. It is also important to consider the economic aspects of the automation project [105]. A 10-step guide to success that emphasizes clearly defined project control in outsourced automation/information technology projects has been published [106]. 

The aforementioned procedure covers an entire lifetime of software, which is usually referred to as the software development life cycle (SDLC). In particular, commercial software development underlies certain regulations that are compiled as a set of standards. Several models can be applied to form a formal point of view. One of these is the V-model its name is derived from the shape of the graphical representation used to describe the required processes (Figure 8.1). 

SDLC documentation underlies a strict approval process that is defined in the software vendor s SOPs and can be audited by customers and regulative organizations. Documents created under the SDLC are versioned and include either handwritten or electronic signatures for approval from the responsible departments. The approval also involves a member of the QA department that is independent of the project team. Different versions of documents may be created as full documents that is, the most recent version includes the entire documentation, or delta documents, that contain just changes with respect to the previous version. 

The final phase in the SDLC covers the implementation — that is, the systematic approach to effectively integrate the software into the process of an organization. Depending on the size of the software, the number of end-users, and the number of interfaces to other software systems, the implementation phase can be anywhere... 

Validation of computerized systems differs from the validation processes previously described because of the complexity and key-function in the process controls of such systems. Therefore, computer validation has a special life cycle (system development life cycle [SDLC]) that contains the hardware and the software. The sub-sections of the SDLC are similar to the subsections of the life cycles for prospective/retrospective validation processes. 

The right side of the diagram shows generally applicable SOPs of the QA System, describing the form and the content of SDLC documents, mainly in form of checklists. The quality of these SOPs is directly related to the quality of the software. 

The individual phases and the phase-independent activities of the SDLC are explained below ... 

Listing of the SDLC documents and who is responsible for preparing them and adhering to work schedules... 

Select qualified suppliers who have demonstrated to work according to proper SDLC (System Development Life Cycle) procedures and who supply good validation support. 

Supplier selection (e.g., selection process, vendor reviews and/or audits [or a documented rationale for the absence thereof], accessibility of the source code, a maintenance contract, proof of application of SDLC principles for internally developed systems)... 

In addition to a defined QMS, a supplier should have a defined SDLC. SAP s SDLC, shown in Figure 14.1, is consistent with current industry practice and... 

The difference in functions between a new release and the previous release should be desaibed. SAP includes development documentation with the issue of a new release, including, for example, detailed specifications of the product s new features. These features are then turned into "real" functions as part of the SDLC. A project plan specifies which functions are to be developed... 

The new functions a release is to contain are incorporated in the existing product during the SAP SDLC. This involves extending the existing process and data models and adding to the application documentation and test catalog. New test case descriptions for new functions are added to the test catalog. New process chains that link the old and new functions in test scenarios are included as test cases. 

The SDLC was developed as a methodology to aid in the development of information systems. By defining the major activities in the process, the SDLC ensures that tdl the required tasks are completed, and the time and resources necessary in the different phases can be more precisely estimated. The SDLC separates the tasks that have to be performed when developing an IS into five phases ... 

After the system has been installed, the system enters the use and maintenance phase. In order for the system to deliver value to the organization, minor maintenance typically is necessary to correct errors, ensure system currency, enhance features, or adapt hardware. The system will be periodically tested and audited to increase the reliability of the system outputs. When the system ages to a point where it can no longer be easily modified, the SDLC will shift back to the planning phase and the life cycle will begin again. 

This section examines the models and methodologies that are used during the different phases of the SDLC. 

Structured English has been found to be a good supplement to DFDs because, in addition to helping developers at the implementation stage, they have been found to be a useful way to communicate processing requirements with users and managers. They are also a good way to document user requirements for use in future SDLC activities. 

During the analysis phase of the SDLC, data are represented in the DFDs in the form of data flows and data stores. The data flows and data stores are depicted as DFD components in a processing context that will enable the system to do what is required. To produce a system, however, it is necessary to focus on the data, independent of the processes. Conceptual data modeling is used to examine the data at rest in the DFD to provide more precise knowledge about the data, such as definitions, structure, and relationships within the data. Withoirt this knowledge, httle is actually known about how the system will have to manipulate the data in the processes. Two conceptual data modeling tools are commonly used entity relationship diagrams (ERDs), and data dictionaries (DDs). Each of these tools provides critical information to the development effort. ERDs and DDs also provide important documentation of the system. 

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