6. Storing and accessing the data

This section covers how the data is stored and how people access the data.

 

1. Storing the Data

The computer systems throughout the airport store thousands of pieces of data every hour. This data is stored in files held on hard disks on various computer systems.

The British Airways computer has files containing passenger information. The Airport Operating System has files with data on landings and departures, flight times, staff employed at the airport and costs and billing information.   

 

 

Updating the Data

The data in these files are continuously being updated 24 hours a day to make sure that they are accurate. Without the latest up-to-date and accurate information, planes would not get their correct landing times, fuel or their catering supplies. The airport simply would not be able to function safely or efficiently.

 

Backing Up the Data

If the computer system has a problem and data are lost it is vital that they can be recovered immediately.

That is why the computers in the airport have an effective backup system.

As data are stored on the hard disks attached to the airport’s computer systems they are also immediately copied on to a second set of hard disks. If there is a problem with the first set of hard disks the second set kicks in and the data are instantly available.

 

 

 

2. Accessing the Data

There are two main methods of accessing the data sequential or random/direct access.

a. Sequential access

When a system uses sequential access to data it goes to each record in a file one after another in sequence. Sequential access is commonly used when recovering data from taped backup systems. Magnetic tape is often used because of its cheapness.

Sequential access is similar to the users access songs on a cassette or video tape. With a song or program towards the end of the tape, you have to wind through the tape to get to it. Accessing information can be quite slow.

b. Random or Direct Access

A system using random/direct access goes directly to the data it requires. As we have seen, the computer systems at the airport use interactive processing, which means that data is processed immediately. This requires direct/random access to the data held on backing storage and is used throughout the airport computer system.

This is the same method used for accessing songs or data stored on a CD. There is no delay to get to the last song on the CD. The read head can go straight to song required.

 

3. Where the data is stored.

 

a. Multi-user Databases

A multi-user database is a database that allows many users access at the same time and if a user has the authorisation, he or she will be able to update the data for the other users.

At Glasgow Airport there are several multi-user databases in use. British Airways uses several multi-user databases containing files on passenger information, files on baggage and files on flight movements. These files are constantly being updated as people and their baggage are checked in at airports around the world. The databases are accessible simultaneously to many authorised BA staff members not just at Glasgow Airport but around the world. The public can even access a BA multi-user database through the internet in order to check flight details, costs and even to book a seat online.

At the airports there are e-booking kiosks where people can check themselves in. These e-booking kiosks are connected to the passenger information files held on a multi-user database and update the files as people check themselves in.

 

b. Why BA uses multi-user databases

BA uses multi-user databases:

• To enable many staff members, as well as passengers, to enter and check data on flights and bookings.
• To enable the staff around the world to trace baggage and make sure that it gets to the correct destination.
• To provide online internet access to the public on flight availability, times and costs.

At the heart of the Airport Operating System is a multi-user database containing information about times, landings and departures. Many people around the airport have access to this vital information: the baggage handlers; the ground crew: cleaners, caterers, crews who refuel and maintain the aircraft; the public; the airline companies and the staff managing the airport.

 

c. Database structure

CDP Systems are only possible because of databases. Data within Databases have a particular structure.

1. File: An organised collection of data on a related topic.
2. Record: All the information related to one particular item within the file.
3. Field: Each separate item of data within the records is stored in fields.

A database file is updated whenever it is changed, either by adding, deleting or editing existing data within the file.

 

 

 

 

What you have to do!

Either in a new Word Document or in your Brain. Under a Sub Heading Processing the Data complete the following tasks.

1. Why does the airport operating system need to use interactive processing?

2. Give two examples of situations where the British Airways computer uses interactive processing.
   

 

 

What you should now be able to do!

• Explain what is meant by the term 'Interactive Processing'.

• Describe the difference between 'Interactive Processing' and 'Batch Processing'.

• Identify the most suitable type of processing to use in given situations.

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Continue to 7. CDP Cycle: Data Output