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software development methodology in software engineering
three basic techniques used in structured programming
software development methodology in software engineering
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Systems Development
Systems Analysis and design - What's wanted
Systems Development - Building and Programming
Systems Implementation and review - Testing and training
Structured Methods
In the 1960's there were a large number of grand scale projects which came to a disastrous end due to being delivered late, over budget and not working. The reason for this was a chaotic development process e.g. Sid goes ill and no one knows what he has been programming!
As a consequence of this, structured methods have been developed. This is where engineering principles have been applied to the development process (hence the term `software engineering') breaking the whole process up into a series of clearly defined tasks, producing specific deliverables.
Development Process
Outline
Process Deliverable
Set Aims Aims
Investigate Facts
Facts about old system. Requirements of new system
System Analyse Requirements spec. (User requirements)
System Design
Detailed system spec.
System prototype Complete Prototype of running system
Logical Model
A logical model has no physical constraints. (I.e. who does what where? etc.)
A logical model IS processes and data which uses processes.
The Development Process in Detail
Charting
* Systems Flowchart
(shows the physical relationships between parts of the computer system)
* DFD - Data Flow Diagram
(shows the flow of Data within the system)
* Program Flowchart
(shows the flow of logic within a program/module. This is another way of describing an algorithm)
* EAR Model - Entity, Attribute, Relationship model.
(Used to show the relationship between stored data in the data model analysed in data analysis)
* Gantt Chart
(Use...
... middle of paper ...
...ompanies are audited by accountants who will want to trace what has happened to selected documents).
Reconciliation - the computer will then recalculate what the batch and hash totals ought to be by using the raw data keyed in off the source documents and will compare these totals with the totals entered from the batch control slip. If there is any discrepancy the batch must be checked and re-entered. This process is particularly good at spotting missing source documents (i.e. if two documents in the batch are stuck together or one gets lost).
File Total Reconciliation - An overall file total can be calculated from summating all the control totals for each batch.
batches of source documents 50 batch totals
This process will pick up situations where complete batches have been mislaid or entered twice!