RELATIONSHIPS BETWEEN INFORMATION PROCESSES Remember information processes are actions that direct and coordinate the system’s

resources to affect the data within the system in some way. As we are dealing with information systems there must be a flow of data and/or information into and out of the system. There must also be a flow of data into and out of each information process within the information system itself.

Fig 2.1 is a generalised context diagram, it shows data and information flows between the system and its environment.

Each data flow arrow is labelled to describe the nature of the data. Data moves into the information system from an external entity in the environment. An external entity that provides data to an information system is known as a

‘source’. A source may be an indirect user, a communication link from another system or any other source of data that is external to the system. The information processes within the system perform their actions on this data and output the resulting information from the system. An external entity that is the recipient of output is known as a ‘sink’. An information system can have multiple sources and multiple sinks; it is also common for a single external entity to be both a source and a sink.

Fig 2.1

Context diagram for a typical information system.

External entity (Sink) External

entity (Source)

Information Processes Information system Input

(Data)

Output (Information)

Consider the following:

A keyboard can be considered to be an information system. It obtains input from the user as they type, it then processes these keystrokes into digital signals that are output to the computer.

Let us now discuss the flow of data between the information processes within a typical information system. Fig 2.2 is a dataflow diagram that includes each of the seven information processes specified in the syllabus. The aim of this diagram is to illustrate the complex flow of data that occurs between information processes. For example, data may be collected, organised and stored. At a later time this data may be

retrieved and processed, the results may then be analysed and displayed. This example is but one of an almost infinite number of ways of following the complex network of data flows shown on the diagram. It is important to realise that on data flow diagrams there is no attempt to describe the order in which the processes occur, as the name

‘dataflow diagram’ implies, they describe the movement of data between information processes. Despite this, it is often true that the nature of the processes involved tends to imply a particular order.

You may notice that not all the information processes on the diagram are connected to each other in both directions, and others are not directly connected at all. Why is this?

In many cases the nature of the data output from a certain process requires further processing before it is suitable as input to other processes. Consider the collecting information process; before data collected can be stored it must be organised into an appropriate format for storage. Displaying is a process that outputs data from the

GROUP TASK Activity

Draw a context diagram to illustrate the flow of data described above.

Do you think a keyboard really is an information system?

Information system

Data store

External entity (Sink) External

entity (Source)

Analysing

Storing and Retrieving

Transmitting and Receiving

Displaying Collecting

Processing Organising

Fig 2.2

Dataflow diagram showing some of the possible data flows within an information system.

system, therefore it accepts input from other processes but only outputs to external entities. Data stores are locations where data is permanently stored; such as files, databases or even filing cabinets. It therefore makes sense that ‘Storing and Retrieving’ is the only information process that deals directly with data stores.

So far we have discussed the relationship between information processes in terms of data flowing between each of the information processes. Another important relationship between information processes concerns the order in which these processes occur. Each unique information system will have different processing requirements in regard to order, however there are some processing sequences that tend to exist in most information systems. The systems flowchart shown in Fig 2.3 describes some of these sequences. For

example, at least some data must be collected prior to commencing any of the other information processes. This data must also be organised appropriately prior to analysis or further processing. Although systems flowcharts are not part of the IPT syllabus they are useful tools to indicate the logic of the information processes, which is essentially the order in which each process occurs.

The systems flowchart shown in Fig 2.3 seems to indicate that collecting must be complete before the organising process commences and similarly organising must be complete prior to analysing and processing beginning.

This is not the intention, rather the intention of Fig 2.3 is to show the path taken by an individual unit of data once it has entered the system.

GROUP TASK Activity

Use a word processor to create, format, save and print a simple one-page document. Whilst performing this task make a note of each of the different information processes occurring together with the exchange of data between these processes.

GROUP TASK Discussion

No doubt your notes from the above activity indicate a certain sequence of events. Must this sequence be strictly followed? Discuss.

Paper document Online

display Communications

link Transmitting and Receiving Storing and

Retrieving

Permanent storage

Online input

Manual input

Analysing Processing Organising

Collecting

Displaying

Fig 2.3

Systems flowchart showing some processing sequences that tend to exist in most information systems.

Consider the following:

A florist sells flowers over the phone, in person or via their website. Each time an order is received it is entered into the store’s computer system. Once the sales assistant enters the customer’s name they are presented with a list of possible matches from the customer database. The sales assistant can either select one of the possible matches or enter a new customer. Customer details are entered even for ‘in person’

orders; this provides a marketing tool for the florist whereby they can examine purchasing trends for individual customers and send them advertising brochures at appropriate times. If an order is to be delivered then it is printed and placed in an ‘in tray’ for later completion and dispatch. At the end of each day the owner generates a sales report detailing the number of each product sold, number of each product remaining in stock, together with the total value of all products sold. Examining this report each day assists the florist make suitable stock purchases when they visit the markets each morning.

COLLECTING

In previous sections we alluded to collecting as the information process that gathers data from some outside entity.

This is true; collecting is essentially an input process, its purpose being to provide data from the environment to other information processes within the information system. For example, entering keywords into a search engine on the Internet is a collection process and so too is scanning an image using a flatbed scanner. In both cases data is entered or captures from the environment for use by the system’s information processes.

To perform this collecting input process requires more than just the actual entry or capture of data; it requires an understanding of what data is required, from where it will come, together with how the data will be encoded. Consider

performing a search using a search engine – the search engine is the information system. In this case the search criteria entered must comply with a particular syntax defined by the collection process, that is; the search engine system defines the data it needs and users must comply with this definition. The source of the search criteria (data) is the user. The data is entered via the keyboard using a text box on a web page being viewed on the user’s remote computer. During data entry the search criteria is encoded into a sequence of ASCII characters using the keyboard, web page, web

GROUP TASK Discussion

Read through the above scenario and identify each of the syllabus

information processes occurring. Reread the scenario and identify the data used by the system and the information produced.

Collecting

The information process by which data is entered or captured by a computer system.

DECIDING WHAT DATA IS REQUIRED DETERMINE THE SOURCE OF THE DATA DETERMINE HOW THE DATA WILL BE ENCODED

ENTER/CAPTURE