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4.3 Ethical and legal considerations You will need to be aware of privacy and confidentiality in relation to online communication. Email is generally considered private and should not be quoted without permission. Some conferences are not wholly public, so messages should not be copied outside the conference. Online discussion may be read by people from other cultures and backgrounds, so be careful to avoid giving offence. Although people are usually very tolerant, it is still possible that someone could sue for libel.
4.2.4 Make clear your perspective Try to avoid speaking impersonally: 'This is the way it is…', 'It is a fact that…'. That will sound dogmatic and leaves no room for anyone else's perspective. Why not start, 'I think…'? A common abbreviation is IMHO (in my humble opinion) – or even IMNSHO (in my not so humble opinion). If you are presenting someone else's views, say so, perhaps by a quote and acknowledgement.
2.2 Evaluating web resources One of the good things about the Web is also one of its drawbacks – anybody can publish anything. This means that the Web is an amasing source of information and is full of fascinating resources. However, in order to get to useful information you may have to work your way through lots of irrelevant material. Even when you think you have found something relevant, how do you know it is reliable, and how can you judge the quality, accuracy and bias of what you find? Most publicatio
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6.6 Modelling the relationships between use cases There are two situations when you would consider adding details to a use case diagram: to identify a common task (and its associated scenarios) that is shared between two or more use cases; to record any alternatives or additions to the main success scenario as separate use cases. In both situations, the new tasks are shown as new use cases (ovals) and, as you will see below, the UML provides a suitable notation (known as
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
7.2.1 E-shop This is the most ubiquitous form of commerce on the World Wide Web. It involves a company presenting a catalogue of its wares to internet users and providing facilities whereby such customers can purchase these products. Almost invariably such a site will contain facilities for ordering and paying for products by means of credit cards. The sophistication of sites described by this business model range from just the simple presentation of a static catalogue to the presentation of an interactiv
5.6 Design Designing a distributed system can also be a problem, for example the fact that computers in a distributed system are joined by communication media which can stretch over thousands of miles provides an added dimension to the design process in that response time can be a problem. Another, equally serious problem is that of reliability, for example the fact that a hardware malfunction can bring down a poorly-designed distributed system. As an example of one design problem that a distribut
Harrowlegal-Contract Dispute Lawyers 5.5 Problems with transactions A distributed transaction is a sequence of operations applied to a number of distributed databases which form a single functional step. For example, a transaction which moves an amount of money from a customer's account to an account owned by the same customer is an example of a transaction. It consists of two operations: the operation of debiting one account and the operation of crediting another account. There are a number of problems associated with distributed transactions. This section w 5.4 Structure and data A problem that is being increasingly experienced by internet companies is the fact that they have to interchange a large amount of data and that such data inherently lacks structure. For example, HTML has proved to be an enduring markup language for developing web pages; however, there are no facilities within the language, for example, to indicate whether an item of data, say a three-digit number, represents the price of a commodity or some hourly rate charged by a company employee. Th 5.2 Programming and abstraction In the early 1990s programming an application for the internet was a tough proposition. I remember that I once had an application which required a very simple form of communication with another application located at a remote computer. I used a technology known as Winsocks which required me to carry out some pretty arcane code development just to send a simple test message to another computer and to receive a reply from that computer. Java, when it appeared in 1996, enabled developers t 5.1 Security and privacy The internet is not a particularly secure place. There are two aspects to this: the first is that information is widely published throughout the internet which can be used for criminal and near-criminal activities. The second aspect is that since the internet is an open system, details of its underlying technologies are freely available to anybody. This means that the way data passes through the internet is in the public domain; the consequence of this is that, theoretically, anyone with the 6.1 What is a business model? The aim of this section is to look at some of the business models which have been used to drive internet applications. A business model is a high-level description of an application type which contains all the common features which can be found in specific examples of the model. For example, one of the most popular business models is the e-shop which describes a website that sells products. The model is general in that it does not describe the item that is sold or the mechanisms that a 5.4 The Sydney Olympic Games system IBM was responsible for the computer systems which were used in the 2000 Olympic Games. There were a number of components to the system, these included: A website which was publicly accessible and which contained features on the Games, the competitors and the results. A Games management system which administered the logistics of the Games, for example arranging transportation, accreditation and accommodation for athletes. 5.1 The architecture of a typical e-commerce system Before finishing this course it is worth looking at the architecture of a typical e-commerce system in order to see some of the technologies. This is followed by details of a real application which I shall use to discuss some of the issues involved in distributed system development. The description used is closely modelled on the Amazon site. 4.6 Problems with transactions A distributed transaction is a sequence of operations applied to a number of distributed databases which form a single functional step. For example, a transaction which moves an amount of money from a customer's account to an account owned by the same customer is an example of a transaction. It consists of two operations: the operation of debiting one account and the operation of crediting another account. There are a number of problems associated with distributed transactions. This section w 2.7.5 Email providers These are sites which provide free email facilities; often they provide other facilities such as sending anonymous mail and constructing mailing lists. Such sites are valuable to users who are too impecunious to be able to afford conventional mailing software and to frequent travellers who can access such sites anywhere in the world. Their main disadvantage is that they tend to be slow compared with conventional mailing utilities such as Microsoft Outlook and Eudora. 2.7.4 Change notification sites These sites are a variation on link checking sites. Here, the customer is notified not when a web document becomes unavailable, but when the document is changed. For example, the customer might be interested in a particular page which advertises some holiday package offers to a particular destination and wants to keep abreast of any changes to the page which might signal the fact that a new improved offer has been added.
Video link (see supported sites below). Please use the original link, not the shortcut, e.g. www.youtube.com/watch?v=abcde