Software development principles

Software Development Principles High-Low Open-Closed Principles... 

SOFTWARE DEVELOPMENT PRINCIPLES HIGH-LOW OPEN-CLOSED PRINCIPLES... 

Please note that layers and tiers are two different concepts. Tiers mean the physical separation of subsystems—each subsystem runs on a different hardware or the same hardware but in different processes. In a multitiered system, the interaction between the subsystems is accomplished through remote procedure calls (RPCs). Any RPC involves network overhead and therefore has a performance penalty whether the remote procedure is on a separate hardware or on the same physical hardware but in a different process. Layers, on the other hand, are logical separations of the subsystems. Each layer can run on a different physical tier, or all layers can run on a single tier. The purpose of physical tiers is to leverage distributed hardware resources or to reuse a piece of software that is deployed on a different hardware that your system wants to leverage. The purpose of layered software architecture is to separate the system into highly cohesive and loosely coupled modules (see Chapter 2 for software development principles). 

Larman, C. 2005. Applying UML and Patterns An Introduction to Object-Oriented Analysis and Design and Iterative Development, Third Edition. Prentice Hall. Martin, R. 2003. Agile Software Development Principles, Patterns, and Practices. Prentice Hall. 

Software Validation Authorities are demanding rules in order to outline the software validation principles used in medical device software or the validation of software used to design, develop, or manufacture medical devices. 

The U.S. Food and Drug Administration (FDA) has developed principles of software validation [3] and computer systems [4] used in an FDA 21 CFR Part 11-regulated environment. 

The discipline of chemometrics provides a number of methods to deal with such problems. During the last years many of these methods became available for PCs, either by statistical software packages or by specific software developed by chemists. A variety of chemometric methods is, in principle, now available at the chemist s own desk. Although the chemist usually is not an expert in multivariate statistics he/she is forced to use such methods, because of the complexity of actual problems in chemistry. 

This definition embraces all uses of computer systems and has been widely adopted, albeit with modifications, by the various GxP regulatory authorities around the world. These are sometimes dubbed computerized systems. The creation of validatable software is, in the first instance, largely a matter of the software developer adopting the basic principles of good software engineering practices under formal documented quality assurance supervision. 

In parallel with these industrywide quality improvement efforts, the software industry had recognized the need to identify processes and standards that assured the quality of commercial software. ANSI (6) and IEEE (7) have been issuing practice standards and dehnitions for many years in an effort to unify quality assurance methodology in the software development industry. Furthermore, the software industry recognized early on that establishment of quality principles prior to the initiation of a development effort reduced the cost of repairing faulty software later in the process (8). 

Software development should follow the principles of Australian Standard AS 3563 Software Quality Management System. 

We have already established that documentary evidence is central to validation. However, the same principle applies to the control of any industrial or manufacturing process software development is no exception. Unfortunately, documentation can quickly degenerate into a bureauaatic nightmare and thus justly attract the contempt of everyone, unless it is conducted in accordance with standards of good practice. Otherwise, far from being recognized as a crucial asset on which the success of the operation depends, it serves to undermine the very efforts to achieve the effective QA that it purports to support. 

The safety characteristics of the SP1NL1NE3 solution and the stringent and proven safety software development process applied by the Nuclear department of the Schneider Electric company have made acceptable the principle of a design based on redundant identical processing units for this project. In addition, because of the possible consequences in case of the NIS not performing its protection fonction on demand, the licensing authority has required an FMEA oriented toward the SCCF risk as part of the safety case. 

The following principles, described in Cusumano and Selby (1995) and paraphrased here, describe the key software development strategies Microsoft employs ... 

Risk has always been a feature of projects in more traditional engineering fields and generic approaches to project risk have been developed. Software engineering thinkers, such as Barry Boehm, have considered how these generic principles can be applied to software development. 

Some analytical equipment include routines for calibration and quality control of analyses that are predetermined by the software developed by the manufacturers. In these circumstances, the principles and practices elaborated above may be unrealistic and analysts are forced to follow protocols as directed by the equipment. 

In the proposed BBN, as a general principle, we model the rigour of application of any method (its effectiveness), in terms of two subsidiary concepts the inherent power to do the job ( power of build/verification method i nodes) and the intensity of its application ( intensity at which build/verification method i was applied nodes). The multiple node notation presented in Figure 3 indicates that every phase of the IEC61508 safety software development lifecycle has one or more build and verification methods, the precise number of nodes depends on -... 

Vidal, F. P., et al. Principles and Applications of Computer Graphics in Medicine. Computer Graphics Forum 25, no. 1 (2006) 113-137. Excellent review of the state of the art. Discusses software development, diagnostic aids, educational tools, and computer-augmented reality. 

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