Read the following scenario about an online reservation system, then carry out the tasks below.

Global-Travel, an on-line reservation system

Global-Travel is an airline that sells all its tickets through an on-line system on the Internet. Prospective travellers register their details by filling in the form available on the company's web site. Once a registration has been confirmed as valid, the travellers can proceed by selecting the destination to which they wish to travel, the date of travel, and the type of ticket they wish to purchase. Only those of destinations to which Global-Travel flies appear on the list of destinations for customers to choose from. Once a destination has been selected, the date box displays only those days of the week on which Global-Travel flies to the selected destination.

Once all ticket details are entered, the customer submits the details to the systems by clicking on the appropriate button. The system responds by either accepting the reservation or rejecting it. If a reservation is rejected, the system displays the reason (e.g., no available places on the specified date or no places available on the specified date for the selected type of ticket). The customer may then choose to change the date of travel, upgrade his/her ticket or abandon the reservation.

If a reservation is accepted, the system prompts the traveller to proceed to the payment section to purchase the ticket or reserve it for 24 hours. Global-Travel web site has a secure server and accepts payments by most credit and debit cards. Once the traveller completes the payment section, the system displays the details of the purchased ticket and requests the traveller to check the details and confirm or abandon purchase by clicking on the appropriate button.

The marketing department at Global-Travel has another information system that is linked to the online site and monitors sales of tickets on all flights. It uses this information to frequently display various promotions and special offers on the site. The accounting department system is also linked to the online site and receives all payment information.

Review question tasks - Answer the following questions based on this scenario:

A discussion of this question can be found at the end of the chapter.

Do the following, based on the Global-Travel scenario:

A discussion of this question can be found at the end of the chapter.

Read the following scenario about an automatic train system, then carry out the tasks below.

ARTC, an on-line reservation system

A railway authority have been asked to fit all its trains with an automatic signalling control system within five years. The main objectives of the project was to increase the safety of rail travel by:

The “Automatic Railway-Train Control System” (ARTC) system should alert the train driver when the train is approaching a red signal. The alert of a red signal must take the form of audible sound and visible red light in the driver's cabin. The alert must start at a specified distance from the red signal (called the red signal alert point), and at the very least the light must continue to be on until the signal switches back to green. The alert sound must also stay on until the driver switches it off. The switching off of the light is used as an acknowledgement that the driver has heard the alert. The level noise from the alert sound increases until it gets switched off.

The ARTC system checks and records the train speed each time it passes a red signal alert point (RSAP). If the train speed was higher than it should be at this point, the system should alert the driver to slow the train down.

The action taken by the driver after his/her train reaches a RSAP depends on the system that would be installed. Currently there are three different systems available.

The first, called Fully Automatic Railway-Train Control System (FARTC), takes over the breaking and the driving systems of the train after it passes a RSAP and gradually brings the train to a halt before the red signal.

The second, called Semi-Automatic Railway-Train Control System (SARTC), does the same as FARTC but has to be triggered by the driver and can be over-ridden also by the driver.

The third, called Automatic Alert Railway-Train Control System (AARTC), simply alerts the driver of the red signal and expects him/her to stop the train before the signal.

The choice of system will depend on the budget and the time-scale allowed.

Tasks

Answer the following questions based on this scenario:

A discussion of this question can be found at the end of the chapter.

Do the following, based on the ARTC railway scenario:

Describe some of the control (feedback) mechanisms that were mentioned in the case study and their function. State the inputs and output of these mechanisms and how the feedback process could affect them.

A discussion of this question can be found at the end of the chapter.

Describe what is meant by an information system?

A discussion of this question can be found at the end of the chapter.

Describe one example from your own experience of each of the following types of systems:

A discussion of this question can be found at the end of the chapter.

The United Kingdom has been debating whether to join the single European Currency for a while now. What might be some of the consequences to organisations whose business is the export of hand-made furniture to EU countries and the USA? How would these consequences influence decisions about software and information system development?

Legacy systems are old software which continues to be used today, even though continual, ad-hoc updating of the software has introduced many bugs and inconsistencies. What are the potential pitfalls to keep in mind when updating software in order to avoid producing (in the long-term) inefficient software that we would consider to be legacy software?

A discussion of this question can be found at the end of the chapter.

A seminal work on software engineering is Fred P. Brooks's paper, “No Silver Bullet — Essence and Accident in Software Engineering”.

An important concept that he tells us is that:

In the above quote, Brooks is arguing that our ability to manage the direct tasks of the programming and production of the software itself is no longer a major problem: tools and techniques exist to help us handle this. The problem of software engineering is in managing the conceptual aspects of it: the software's specification and design, and the testing of this specification and design.

We cannot expect tools to automatically manage or drastically lesson the conceptual problems related to software engineering: there is no “silver bullet”, no tool that will solve it all; there is only sound engineering practice.

This paper is available online in an abridged form. Find a copy and read it.

There is no discussion section for this review question.

Describe the context of Global-Travel online sales system.

The system is in the context of providing a service to potential passengers, providing a communications medium for messages from the marketing department and providing booking, reservation and payment data to the sales function of the company.

Describe the collection of information that is relevant to that context.

Information is collected from the customer, the marketing department, the seat availability database, and the credit reference system.

Specify who has access to this information.

The customer has access to information fitting their request. Sales has access to booking, reservation and payment information. Marketing has access to the sales information and the seat availability, on which to base its promotion decisions.

Describe the inputs and outputs of the system.

Inputs from the customer include:

Inputs from the marketing department include:

Inputs from the sales department include:

Output to the customer include:

Outputs to the marketing department include:

Outputs to the sales department include:

From the point of view of a prospective traveller, describe the feedback loops in the system and how this affects the input and the output of the system.

The system displays only information about flights meeting the traveller's requirements. If the requirements change, the system responds with new suggestions.

If there are seats meeting traveller's requirements the system requests a booking/reservation decision.

The system responds to it information on the validity of the payment offered by the user.

Describe the possible boundary of each of the proposed system.

The boundary of FARTC is simply the system's interaction with the RSAP, the braking system itself and some method for the system to know how hard the brakes need to be automatically applied.

The boundary of SARTC needs to include the driver, since the trigger by the driver will make the SARTC system start to break the train. The system must also include the braking system to be applied and the RSAP signal.

The boundary of AARTC should include the RSAP and the driver. Since this system does not make the brakes come on, there is no need to include the braking system as part of this information system.

Discuss how they differ and why

The first system does not need to include the human driver — all that is required is a signal requesting that the noise stop playing.

The second system must include both the driver and the braking system, since the driver needs to engage the SARTC system, and can also provide the input of overriding the system.

The final system does not include the braking system at all, since it is simply an alarm system to be switched off by the driver.

The FARTC system has three main feedback loops:

The SARTC system has five main feedback loops:

The AAARTC system has two main feedback loops:

The driver switched off the light

We might define an information system as a system of interrelated elements working together to achieve some goal, composing of:

Obviously in this module we are most interested in information systems that are comprised chiefly of software components.

Real-time systems: Examples should be systems that respond to changes in very short times. Examples might include:

Data-processing systems: Examples should refer to systems that process large amounts of data, and possibly provide communication with some larger network of computer-based systems. Examples might include

Decision-support systems: Examples should be about systems that attempt to analyse data in terms of certain models, and perhaps predictions of future outputs based on extrapolations of the data. Examples might include:

Expert systems: Examples should be about systems that model human expertise and decision making. Examples might include:

There are a number of consequences, including:

Implications for software system are that any existing systems will need to be changed. It might be that the company has a sister-company elsewhere in the EU, so perhaps a decision about which information system (or which bits of each) should be retained so that both companies will move towards using the same system. The jobs done by staff for processing EU sales will probably be simpler (and different) from the processing of USA sales, and the human and computer information system needs to be adapted to make such different order processing straightforward.

An important thing to consider when updating software is that the changes are properly engineered: while all changes to software can introduce inconsistent behaviour, inefficient behaviour, and bugs, when bad software engineering practices are followed this is much more likely to occur.