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6.1 Modularity and the object-oriented approach

In the previous sections we discussed software development processes and the role of modelling. In this section you will meet the main object concepts. Object-oriented programming preceded object-oriented development by many years, and it is where the object concepts originate. Once we have explained these concepts, we shall revisit software development and modelling in object terms.

One of the great successes of software engineering over the past 50 years has been the introduction of m
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5.1 Domain, specification and design modelling

Building quality software is often a complex and lengthy task. Software developers build models that represent what is important, devoid of unnecessary detail. These models help them to deal with the complexity and to understand what is being developed.

This is not unlike other forms of design. For instance, when an architect develops model of a house as a set of drawings they will probably show where the walls and windows are and their relative sizes, but not any details about t
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2.2 From waterfall to iterative development

Historically, the first widely adopted software development process was the waterfall development process (or simply, waterfall).

The waterfall process relies on the definition of sequential phases, as shown in Figure 1. Each phase starts only after the previous one has finished; all the analysis i
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6.9 Alternatives to the main success scenario

If a use case incorporates a scenario that is significantly different from the main success scenario, you may decide to create a new subsidiary use case. There may even be a need to create more than one subsidiary, depending on what happens in different circumstances. For example, when making a reservation in a typical hotel the receptionist would first determine whether the guest was already known to the hotel (among other advantages, this would speed up the reservation process since re-ente
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6.5 More about actors

In the hotel example, you saw two actors in the use case diagram shown in Figure 3 (reproduced below). Why is the actor Guest associated with the use case for making a reservation but not associated with the use cases for checking in and out? The answer comes from an understanding of what happens when someone, a guest, arrives at a hotel. Hotels are service oriented. That is to say, they offer certain services to their guests with the intention of earning money for the business. A hote
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2.4 The message passing idea

Figure 1 shows the central idea behind the message passing paradigm. It involves an architecture in which clients and servers communicate using communication lines. In this model, in contrast with the others that are to be presented in this unit, the underlying structure of the network is visible via the communication media used to connect servers and clients and devices such as sockets, ports and server sockets which are involved in the transfer of a message from one computer to another.


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Acknowledgements

The following material is Proprietary (not subject to Creative Commons) and used under licence (see terms and conditions).

Grateful acknowledgement is made to the following for permission to reproduce material:

Ince, D. Developing Internet Applications, chapters 1 and 4, published by Pearson Education Limited in collaboration with The Open University, © Pearson Education Limited, 2002, 2003. This publication forms part of an Open University course M360 Developing
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6.2 The application

The first application I shall describe is that of an online bookseller. Such a book sales system would carry out a number of functions:

  • It would allow the user to browse through a catalogue of books.

  • It would allow the user to browse through a list of the most popular books, with the list being updated every hour.

  • It would provide the facility whereby a user can buy books and add them to a notional shopping basket.
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1.8 Maintenance

Databases are one of the more enduring software engineering artefacts; it is not uncommon to find database implementations whose use can be traced back for 15 years or more. Consequently, maintenance of the database is a key issue.

Maintenance can take three main forms:

  • Operational maintenance, where the performance of the database is monitored. If it falls below some acceptable standard, then reorganisation of the database, usuall
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1.7 Testing

The aim of testing is to uncover errors in the design and implementation of the database, its structure, constraints and associated user and management support. Testing is usually considered to involve two main tasks – validation and verification. Without adequate testing users will have little confidence in their data processing.

Validation answers the question: has the right database been developed to meet the requirements? It attempts to confirm that the right database has been co
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1.6.4 Supporting data management strategies

Most of the development we've covered so far in this unit has focused on meeting specific user requirements – that is, ensuring the right data are constrained correctly and made available to the right user processes. However, other questions must also be addressed in order to support a data management strategy: How frequently should data be backed-up? What auditing mechanisms are required? Which users will be permitted to perform which functions? Which database tools and user processes wil
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5.2.1 Transforming the natural to the designed

The artist Christine Martell lives in Oregon in the United States and works with beads and visual images. I asked her to describe how she makes use of a computer to create her visual images of flowers and trees. She writes of her work:

I start by finding flowers that are compelling in some way, most often in form and colour. I take photographs with a 35 mm camera having a macro lens.

I'm usually looking for a
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3.4.1 A computer system is the combination of:

  • the computer (with its processor and storage);

  • other equipment such as a scanner or printer,

  • the software programs that make it all work (software programs that are designed to help with some human task are often referred to as applications).


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2.2 The organisation: loyalty cards

Many supermarkets and other firms (such as petrol companies and airlines) use loyalty cards: cards that offer a customer some form of incentive, such as a future discount or gift, to continue buying from that firm. For example, the British supermarket chain Tesco issues such cards. The holder of a loyalty card is regularly sent vouchers which give the holder discounts from their shopping bills and also vouchers which enable them to gain a discount on items that the supermarket wishes to promo
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2.1 The individual: an average day

If I take an average day in my life, I find myself surrounded by computers, most of which are invisible to me. This section looks at where computers are found in the course of everyday life. It aims to:

  • place computers in the context of the activities we do and the things we handle in our day-to-day lives.

But it does this from two points of view: the individual and the commercial organisation.


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Working with charts, graphs and tables
Your course might not include any maths or technical content but, at some point during your course, it’s likely that you’ll come across information represented in charts, graphs and tables. You’ll be expected to know how to interpret this information. This unit will help you to develop the skills you need to do this. This unit can be used in conjunction with the ‘More working with charts, graphs and tables’ unit, which looks into more ways to present statistical information and shows y
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Introduction

This course examines four of the ‘grand theories’ of child development: behaviourism, social learning, constructivism and social constructivism.

This OpenLearn course provides a sample of Level 2 study in Education.


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In this unit you will find a discussion of the national curricula framework in Scotland. This is discussed in terms of the literacy curricula, and compared to the framework set up in England and Wales. First published on Fri, 29 Jul 2011 as Author(s): Creator not set

Your understanding and attitudes to science
What is meant by 'science'? How do political, philosophical and religious beliefs affect scientific discoveries and developments? In this free course, Your understanding and attitudes to science, you focus on your own experiences and knowledge of science, and you look at creative contexts to support children's scientific learning in primary schools and early years settings.Author(s): Creator not set

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This free course, Engaging with educational research, introduces you to the theoretical toolkit that is an essential part of engaging in educational enquiry. You will consider the types of theories and what their role is in the research process. Two very influential research perspectives are examined to identify differences in ways we think about and study the social world.Author(s): Creator not set

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