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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6.2 Authority and the variety of information sources Technology has massively increased the number and variety of news sources that we have access to. We still have printed books, magazines and newspapers, while digital techniques have increased the number of broadcast radio and TV channels that we can get. On the Web we have access to online versions of many of these. This allows us access to media that previously would have been inaccessible. With traditional news sources such as these, we have some understanding of the authority that t
5.1 Transmission of electrical signals on wires In the discussions of newsgathering in the Taylor and Higgins papers, you saw the significance of the development of systems that allowed long-distance transmission of electronic signals. Initially transmission used metallic wires (remember Taylor's reference to the importance of the ‘lines infrastructure’ and his mention of the ‘wire picture’) and later wireless transmission (terrestrial and satellite microwave) became important. In this section I shall look at some aspects of the tr
2.6 New media
Taylor now describes the era when film was replaced with analogue electrical video. 2.4 Comparing early sources of news
Taylor compares the merits of radio and newsreels, as sources of news, with those of newspapers. 2.3 Newsgathering and newspapers
Taylor now discusses some early information and communication technologies and the extent to which they had an impact upon newspapers. Introduction This unit is from our archive and it is an adapted extract from Networked living: exploring information and communication technologies (T175) which is no longer in presentation. If you wish to study formally at The Open University, you may wish to explore the courses we offer in this curriculum area. This unit looks at the technologies used to acquire information about 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 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 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 6.4 Scenarios The purpose of a use case is to meet the goal of its associated actor(s), such as a guest making a reservation with a hotel. This implies that a use case should include everything that must be done to meet that goal. For example, if it is necessary to check the availability of rooms in the hotel for the desired length of stay before accepting a reservation, then we expect the use case to contain that check. In general, a use case contains a narrative about the flow of events that specifies a 6.3 Describing use cases To understand the work, you need a good idea of what each use case means. To get a feel for what this might entail, look again at Figure 3 (reproduced below) which shows a simple use case model for a hotel chain reservation system. Note that Figure 3 is not intended to be an exhaustive model of the hotel domain; the scope of the problem to be solved is confined to reservations and the processes of checking in and out. 6.1 Use case modelling In this section, we take a closer look at use case modelling, and show you how it can be used to model the requirements for a product that includes the development of a software application or, simply, a system. Use case models act as a discussion tool between the requirements analyst and stakeholders, and offer a common language for agreeing the functions of a proposed system. In this discussion, we shall use the Unified Modelling Language (UML) notation (diagrams) for use cases to re 5.1 More information about modelling techniques The four remaining diagramming techniques are described in separate sections below, which you should now study:
From film to videotape
Radio and newsreels
Newspapers
