Topic 1: System fundamentals Flashcards
Feasibility study
Analyses a project and its potential based on the TELOS criteria
Why do we need a new system?
Replace a system that is inefficient
No longer suitable for its purpose, redundant or out-dated.
To increase productivity, quality of the output or minimise costs
The new system should fix errors of the previous system.
Legacy system
Old method, technology, computer system, or application program. It may or may not be available for purchase any more.
Such a system may still be in use because its data cannot be converted to newer format or its apps cannot be upgraded. And if it is, it needs manteinance
Business merger
Combination of two or more entities, especially companies, into one.
Issues that can arise from business merger
Issues of software compatibility
Language differences
Time zone differences
Workforce cultural differences
Remote
Software distribution model in which a third-party provider hosts applications and makes them available to customers over the Internet.
Local
Software distribution model which is installed on the user’s computer system, either on a server on a local network, an isolated computer, or on a laptop.
Advantages of SaaS
Scalable solution:
Businesses simply adjust their monthly subscription as required.
Less expensive: Low initial cost and requires few investments of installation, maintenance and upgrading.
Reduction in staff workload: IT workers are liberated from on-premise hardware and
software tasks.
Variety: Wide range of desktop, portable and mobile devices support SaaS.
Safety: Applications and data reside in the cloud service of the provider’s data center.
Disadvantages of Saas
Data loss: Possible if a SaaS provider goes out of business.
Internet requirement: Performance of web based app, accessed by internet connection is low compared to software running on a local machine or local area network.
Parallel changeover and its pros/cons
The new system is started, but the old system is kept running alongside it. Data has to be entered into both systems.
V If the new system fails, the old systems runs a backup (no loss of productivity), outputs from the two systems can be compared to see if new one is running correctly
X Running two systems is costly in terms of time and money
Direct changeover and its pros/cons
Old system is stopped and new system is started.
V Minimal time and effort, new system is available immediately
X If the new system fails, there is no fall back
Pilot changeover and its pros/cons
The new system is piloted (tested) with a small subset of the organisation. Once it is running correctly and all bugs have been ironed out, it is implemented across the whole organisation.
V All features are fully trialled; if the new system fails, only a small part of the organisation suffers; staff who were part of the pilot can train other staff.
X For the subset of users in the pilot group, there is no backup if the new system fails.
Phased changeover and its pros/cons
The new system is introduced in steps as parts of the old systems are gradually replaced with the new system.
V Allows people to get used to the new system; training of staff can be done in stages
X If the new system fails, there is no fall back for that part of the system.
Data migration
Refers to the transfer of data between different formats, storage types or computer systems.
Problems arised from data migration
Incompatible file formats: Same piece of software might have different versions
Data structure differences: Moving data from a table to a flat file, or from an array to a linked list, might cause a lot of problems.
Validation rules: Due to rules applied to inputs. data can be rejected and lost.
Incomplete data transfers: Data may be lost or not transferred due to an incomplete data transfer because it was interrupted or errors during the process.
International conventions: Problems with dates, currencies & character sets.
Beta testing
Performed by a selected group of clients or end users who are not employees of the organization. Performed at client location.
Alpha testing
Performed by selected group of testers who are usually internal employees of the organisation. It’s performed at developers site.
Dry pen testing
Conducted using pen and paper by the programmer, who mentally runs the algorithm.
Unit testing
Individual parts of the system are tested separately
Integration testing
The entire system is tested to see if all elements work correctly together
Debugging
Systematic process of finding and correcting errors in a program.
User acceptance testing
Testing any new/updated system with its end users to see if it meets their expectation, which is very important.
Validation
Process of evaluating whether the data input meets identified specifications.
Verification
Verification is the process of ensuring that input is the same as the original source data.
User documentation
Any document that explains how to use the features and functions of a system to its end-users. For example, books, PDFs, websites, videos, etc.
Online support and pros/cons
Special web service hosted by the system’s developer to provide user documentation.
V More extensive
- They get continuously revised by the systems developer to deal with the problems occurring most often (FAQs)
- They often provide an option for live support, talking to a real human operator if a problem arises which the user documentation has no answer to
- They often have search capabilities built-in so that users can easily search through them
X They are useless if users have no internet connection
- Live support does not work quite well with users unfamiliar with computers when they have to explain their problem (“I clicked ‘that’ button and then
something happened!”)