Software Engineering Ch 1

Interactive transaction-based applications

Application that execute control systems that control and manage hardware devices. Numerically, there are probably more embedded systems than any other type of systems.

Acceptability

Software must be acceptable to the type of users for which it is designated. This mean that it must be understandable, usable and compatible with other systems that they use.

What is the difference between software engineering and computer science?

Computer science focuses on theory and fundamentals; software engineering is concerned with the partialities of developing and delivering useful software.

What are the costs of software engineering?

Roughly 60% of software costs are development costs, 40% are testing costs. For custom software, evolution costs often exceed development costs.

Efficiency

Software should not make wasteful use of system resources such as memory and process cycles. Efficiency therefore includes responsiveness, processing time, memory utilization, etc...

What are the fundamental software engineering activities?

Software specification, software development, software validation and software evolution.

Stand-alone applications

These are application systems that run on a local computer, such as PC. They include all necessary functionality and do not need to be connected to a network.

Batch Processing Systems

These are business systems that are designated to process data in large batches. They process large numbers of individual inputs to create corresponding outputs.

System of systems

These are systems that are composed of a number of other software systems.

Systems for modeling and simulations

These are systems that are developed by scientists and engineers to model physical processes or situations, which include many, separate, interacting objects.

Entertainment systems

These are systems that are primarily for personal use and which are intended to entertain the user.

Data collection systems

These are systems that collect data from their environment using a set of sensors and send that data to other systems for processing.

What are the best software engineering techniques and methods?

While all software projects have to be professionally managed and developed, different techniques are appropriate for different types of system. For example, games should always be developed using a series of prototypes whereas safety critical control system require a complete and analyzable specification to be developed. You can't, therefore, say that one method is better than another.

Software costs

1. Software costs often dominate computer system costs. The costs of software on a PC are often greater than the hardware cost. 2. Software costs more to maintain than it does to develop. For systems with a long life, maintenance costs may be several times development costs. 3. Software engineering is concerned with cost-effective software development.

Customized Products

1. Software that is commissioned by a specific customer to meet their own needs. Examples - embedded control systems, air traffic control software, traffic monitoring systems. 2. The specification of what the software should do is owned by the customer for the software and they make decisions on software changes that are required.

Generic Products

1. Stand-alone systems that are marketed and sold to any customer who wishes to buy them. Examples - PC software such as graphics programs, project management tools; CAD software; software for specific markets such as appointments systems for dentists. 2. The specification of what the software should do is owned by the software developer and decisions on software change are made by the developer.

Security and Trust

As software is intertwined with all aspects of our lives, it is essential that we can trust that software.

Business and Social Change

Business and society are changing incredibly quickly as emerging economies develop and new technologies become available. They need to be able to change their existing software and to rapidly develop new software.

What is software?

Computer programs and associated documentation. Software products may be developed for a particular customer or may be developed for a general market.

What are the key challenges facing software engineering?

Coping with increasing diversity, demands for reduced delivery times and developing trustworthy software.

What are the attributes of a good software?

Good software should deliver the required functionality and performance to the user and should be maintainable, dependable and usable.

General issues that affect most software

Heterogeneity, Business and social change, Security and trust.

Heterogeneity

Increasingly, systems are required to operate as distributed systems across networks that include different types of computer and mobile devices.

Essential attributes of a good software

Maintainability, Dependability and security, Efficiency, Acceptability.

Dependability and Security

Software dependability includes a range of characteristics including reliability, security and safety. Dependable software should not cause physical or economic damage in the event of system failure. Malicious users should not be able to access or damage the system.

What is software engineering?

Software engineering is an engineering discipline that is concerned with all aspects of software production.

Maintainability

Software should be written in such a way so that it can evolve to meet the changing needs of customers. This is a critical attribute because software change is an inevitable required of a changing business environment.

Application types

Stand-alone applications, interactive transaction-based applications, Embedded control systems, Batch processing systems, Entertainment systems, System for modeling and simulations, Data collections systems, System of systems.

What is the difference between software engineering and system engineering?

System engineering is concerned with all aspects of computer-based systems development including hardware, software and process engineering. Software engineering is part of this more general process.

Software engineering fundamentals

Systems should be developed using a manged and understood development process. Dependability and performance are important for all types of system. Understanding and managing the software specification and requirements. Reuse software that has already been developed rather than write new software.

What differences has the web made to software engineering?

The web has led to the availability of software services and the possibility of developing highly distributed service-based systems. Web-based systems development has led to important advances in programming languages software reuse.