7.2 Difficulties in navigating e-commerce sites People who are new to computing sometimes find the process of online ordering baffling and frustrating. They get ‘lost’ in the process – for example, by putting something into a virtual shopping cart and then remembering that there's something else they need to look for. So they return to the search engine or the catalogue and then can't find the cart. These kinds of commonly experienced difficulties can be addressed by good and adaptive site design, but still a disturbing proportion of
Acknowledgements The content acknowledged below is Proprietary (see terms and conditions) and is used under licence. Grateful acknowledgement is made to the following sources for permission to reproduce material within this unit. Figure 6 NanoElectronics Japan Figure 30 The Cottingley Fairies © Science and Society Picture Library
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6.4 Pictures It used to be thought that a photograph could provide proof of an event – someone could be caught red-handed by a photograph, as proof of their guilt. ‘The camera never lies’, it was said. If you have a digital camera and have been ‘touching up’ photographs on your home computer you will know that this is far from true now. It is easy to lie with a digital photograph. The idea that the camera never lies has always been a myth, however. As far back as 1917 the photographs of th
6.3 Authentication of information When I watch TV news, listen to the radio or buy a newspaper I never think to question whether I really am watching ITV, listening to Radio Five Live or getting the Guardian. In each of these cases it is theoretically possible that they are not who they say they are, but the practicalities of performing the masquerade are so complicated that the possibility can be discarded. With emails and websites it is a very different matter. Indeed, in recent months I have received several e
2.6 New media
Taylor now describes the era when film was replaced with analogue electrical video. 2.2.4 Public services In the UK, in many NHS trusts, patient records are easily shared between departments within a hospital. These electronic patient records may soon be transferable across the whole health service, so that medical staff can access them from any part of the NHS. In some places, especially remote rural areas, doctors may be able to make use of computer networks to make a diagnosis if they are unable to see the patient in person. Passenger information is increasingly available via networked c 8.1 Introduction One type of data model is an entity–relationship data model. Experience has shown that data can be best described by relationships between entities. An entity is anything of interest about which data is recorded, such as roads, weather stations, trucks and weather station readings in the IceBreaker project in the book MRP. In general, there will be many relationships (or associations) linking the entities. A trivial example is the fact that a given weather reading 6.8 Sharing behaviour between use cases For each use case there may be more than one scenario. In the process of requirements elicitation and specification, you may find a certain amount of common behaviour in two or more of your use cases. You may even find that an existing component can provide part or all of that common or shared behaviour. Indeed, if you do find such an existing component, this is an example of reusing requirements which is discussed more fully in MRP. You can record the shared behaviour in 5.1 More information about modelling techniques The four remaining diagramming techniques are described in separate sections below, which you should now study: 1.1 Types of model When the word model is used, you are most likely to bring to mind physical models such as those that are constructed to depict new buildings, cars or other artefacts. Such models are a precursor to actually building the artefact ‘for real’. However, our use of the word goes beyond physical models. For example, when a new house is built there will be a variety of plans produced to show different aspects of the house: its floor plan, a diagram of its location, a drawing of the front elevati 5.2 An example In order to complete this section I shall present a simple example. This is loosely based on one described in [1], currently one of the very few books written on JavaSpaces technology. An object that can be stored in a space has to implement an interface 4.3 A commercial implementation In order to conclude this section I shall describe a commercial implementation of an object bus. It has been developed by a company known as SoftWired Ltd and is known as iBus. It is based on TCP/IP rather than UDP. The facilities offered by the iBus API provide developers with the facilities to construct objects which can subscribe to channels and to transmit any Java object to a channel. The code for a transmitter is shown below; the import statements are not shown. In Making Mergers Less of a Crapshoot 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 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 6.1.1 The user interface An interface to a washing machine does not need to be like the interface to a personal computer (a user interface is a display/control panel that enables the user to control a machine or interact with a program). It is specific to the task of washing laundry, which involves two things: displaying the choices that relate to washing laundry (such as type of laundry to be washed, water temperature, and spin speed); displaying some indica 4.2.2 Using the web more effectively: gateways A gateway on the web is a website intended to direct users to other preselected websites containing information on a particular topic. It can also refer to a computer that acts as a message router on the internet University librarians often set up gateways for particular areas of study, although they may be set up by anyone with sufficient expertise in a topic. Gateways may be fairly general, such as a gateway site for sciences, or more specific, such as a gateway for part 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). 3.1 Making sensation make sense In the previous section you learned something about what data is, where it can be found, and how it can be used. But have you ever thought about how we get data in the first place? As human beings, we are so used to reading, writing, speaking and observing that we rarely think about the true origins of the data we commonly use with such ease. I don't intend taking you back to these origins – that would take too long. Rather, I want to describe how human beings ‘get’ data and put it into 2.1.2 Data and information So far, I have used two words in connection with computers: data and information. Did you see any differences in the way the two terms have been used? Let me point out one. Data refers to discrete items, such as the price of an item on the shelf of a supermarket, or the type of product listed on a sign over a supermarket aisle. The word ‘data’ is a plural Latin word but it is generally used as a singular word in English. In contrast, information involves linking
From film to videotape
Diagramming Technique
Section
Use case modelling
Use Cases and Activity Diagrams
Activity diagrams
Use Cases and Activity Diagrams
Entity–
. The objects that form part of the example will just
Very human factors are at play in mergers and acquisitions. Paying attention to them can increase your chance of success.
