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Information system
Information system is a set of computer components that collect, process, store, and provide all the information needed for business tasks.
Computer application?
A computer application is a software program that executes on a computing device to carry out a specific function or a set of related functions.
What is the purpose of systems analysis? Why is it important?
Just as a builder doesn’t start construction without plans, programmers don’t just sit and start writing program code.
They need someone to function like an architect before writing to code and verifying that it satisfies the vision.
The software architect has to be able to understand and capture the vision of the persons funding the project.
This person is usually called the systems analyst.
Some development teams distributed worldwide, you may only do part of the programming, the rest handled by teams around the world.
In a distributed team situation, it is important to have written documents to assist in detailing the software application.
Systems analysis
Systems analysis consists of those activities that enable a person to understand and specify what the new system should accomplish.
Systems analysis is much more than a simple brief statement of the problem, it must track a myriad of details.
Systems analysts describe in detail the “what” that a system must do to satisfy the need or to solve the problem.
The objective is to understand the informational needs or requirements and to document those requirements in a set of specifications.
Analysis tells us what the system needs to do.
Systems design
Systems design consists of those activities that enable a person to describe in detail the system that solves the need, describing the “how”
It specifies in detail all the components of the solution system and how they work together to provide the desired solution.
The objective of software construction is to build a system that satisfies those requirements.
System design, then, is the bridge that takes us from the requirements to solution.
Design describes how the system will be configured and constructed.
Activities of systems analysis?
Gather detailed information - systems analysts obtain information from people who will be using the system, by interviewing or watching them.
o They obtain additional information by reviewing planning documents and policy statements.
o Analysts also study existing systems, including their documentation.
o They also frequently obtain additional information by looking at what other companies have done when faced with a similar business need
o They tried to understand existing system by identifying and understanding the activities of all the current and future users
o They also identify all the present and future locations where work occurs and all the system interfaces with other systems.
Define requirements - the analyst uses information gathered from users and documents to define requirements for the new system .
o System requirements include the functions the system must perform (functional requirements) and requirements for reliability, performance
and security (non-functional requirements ).
o Analyst creates models to record requirements, review the models with users, refine and expand the models to reflect information.
Prioritise requirements - once the system requirements are understood, it’s important to establish which requirements are crucial for the system.
o Users suggest functions that are not essential. Users and analysts need to ask themselves which functions are important or not required .
o Unless the analysed evaluates priorities, system requirements tend to expand as users make more suggestions (scope creep).
o Requirements priorities also help to determine the numbers composition and ordering of project iterations .
o High priority requirements are incorporated into early project iterations so analysts have opportunity to refine those parts of the system .
o Also, a project with many high priority requirements will have many iterations, develop user interface dialogue with the user.
o User validation of an interface is much simpler and more reliable because the user can see and feel the system .
o To most users, the user interface is all that matters.
o Developing user interface dialogues is a powerful method of eliciting and documenting requirements.
o Analysts can develop user interfaces via abstract models, such as storyboards, where they can develop user interface prototypes.
o A prototype interface can service requirements and be a starting point for developing a portion of the system.
o Using interface prototypes developed in an early iteration can be expanded in later iterations to become a functioning part of the system.
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Evaluate requirements with users – analysts use an iterative process to illicit user input, work alone, return to the user, refine the model.
o Prototypes of devices developed in paper models are inadequate as analysts need to prove their chosen technologies function as planned.
o If the system includes innovative technology, users need help visualising the possibilities available when defining what they require .
o Prototypes can fill that need .
o The process of eliciting requirements, building models and prototypes, and evaluating them with users may repeat many times.
What is a project?
Initial development of a new project is usually done as a project.
What this means is that the activities required to develop a new system are identified, planned, organised, and monitored.
We can think of a project as a planned undertaking that has a beginning and an end and produces some definitive result.
Some projects are very formal, whereas others are so informal that they can barely be recognised as projects.
To manage a project with analysis, design, and other development activities, you need a project management framework as guidance
What are the six core processes of software systems development?
There are many approaches to the SDLC and many variations for projects that have various needs.
There is a core set of processes that is always required, even though there is also an incredible number of variations of these core processes.
How each process is planned and executed and how the processes are combined into a project.
Here are six core processes required in the development of any new application.
o identify the problem or need and obtain approval to proceed.
o Plan and monitor the project. What to do, how to do it, and who does it.
o Discover and understand the details of the problem or the need.
o Design the systems components that solve the problem or satisfy the need.
o Build, test and integrate systems components.
o Complete systems tests and then deploy the solution.
There are many ways to implement these six core processes of the SDLC.
An information systems development process is the actual approach used to develop a particular information system.
What is meant by Agile development?
During the last 10 years, several new information systems development processes have been developed to enhance project success.
One of the newer and more effective ones is called Agile development.
The philosophy of agile development is that no one completely understand the problems and complexities of a new system.
The project plan and the execution of the project must be responsive to unanticipated issues.
It must be agile and flexible.
It must have procedures in place to allow for, anticipate and even embrace changes and new requirements during the development process.
What is the purpose of a System Vision document?
An SVD is developed to identify the benefits to the company and the functional capabilities that will be included in the system.
This is done in two steps, developing a preliminary statement of benefits and then adding estimates of specific dollar costs and benefits.
What is the difference between a system and a subsystem?
As is always the case, the list of systems capabilities provides the foundation information for determining the overall project plan.
The first step is to divide the system into several subsystems or components.
A subsystem is simply a portion of the overall system.
Based on the list of systems capabilities, the project team will identify functional subsystems.
A system or information system is the set of interrelated computer components that collects, processes, stores and provides output.
What is the purpose of a work breakdown structure?
During the planning of the first iteration, the first step is to identify or attempt to identify all the individual tasks that need to be done.
As these tasks are identified, they are compiled and organised.
This organised list of tasks is called a work breakdown structure.
Part of the effort is trying to estimate how long each task will last.
What are the components of a work breakdown structure? What does it show?
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Work breakdown structure shows an organised list of the individual tasks that need to be done and estimate how long each task will take.
The estimates include the time for the work, for discussion, and for reviewing the work breakdown structure for accuracy and correctness.
All the tasks listed in the work breakdown structure are placed in a day-by-day sequence called a work sequence draft.
What information is provided by use cases or a use case diagram?
A use case documents a single user triggered business event and the system’s response to that event.
Eg a purchasing agent goes to a trade show and finds some lightweight jackets that will work well for the company’s fall merchandise offerings.
Maybe the first task the purchasing agent needs to do is find out if the supplier has worked with them before.
Thus, the business event that requires the tradeshow system might be “look up supplier”.
Activities leading up to the event of using the system are important but we do not identify them as events until the tradeshow system is used.
The project team will design a list of use cases, using multiple methods to identify the use cases, usually a brainstorming session.
What information is provided by a class diagram?
Object classes are identified during discussions by looking for the nouns that describe categories of things.
A class diagram illustrates which nouns have been determined to be fundamental object classes for the system.
The attributes are descriptors that help define and describe an object class.
The class diagram provides a list of object classes, designed to represent a visual diagram of the classes, their attributes, and their relationships
Class diagrams are a powerful and frequently used way to understand and document the information requirements of a system.
How does use case diagram and a class diagram drive the system development process?
It is important to note that the use cases help the project team organise its work.
The team will develop a workflow for each use case to understand how it works and identify what screens and reports will be required
A use case and class diagram can help simplify and give visual representations of how the data within the system is used.
A use case diagram can show how each user can interact with the system
A class diagram can show the attributes, class and relationships of the data within the system.
What is another way to describe an activity diagram? What does it show?
One method of documenting the details of a use case is by developing a workflow diagram, which shows all the steps within the use case.
The purpose is to document the interactions between the user and the system.
To develop a workflow, a simple type of diagram called an activity diagram is used.
It is is an illustration of what happens in a workflow, what activities can be done in parallel, and if there are other paths through the workflow.
How does an activity diagram help in user interface design?
To develop a workflow diagram, an activity diagram is used.
In a workflow diagram, the arrows represent the sequence of the flow.
The columns in the workflow diagram represents who performs which task.
The arrows that cross the centre line identify the data elements that become part of the user interface.
User interface design includes all those tasks that describe the look and feel of the system to the user.
As the user interface is the window that users work with to utilise the functionality of the system, the user interface is essentially the system.
A well-designed user interface that is intuitive, easy to use, with a range of features to facilitate navigation, will enhance the utility of the system.
What is the purpose of architectural design?
During architectural design, you determine the overall structure and form of the solution before trying to design the details.
Once you have an overall structure and an overall approach for implementing the new system, you begin to drill down to the subsystem design.
The subsystem is further divided into layers, a view layer and a model layer.
An advantage of partitioning the system into layers is that the system is much easier to build and maintain with this kind of structure.
What new information is provided in a design class diagram (more than a class diagram)?
A design class diagram (DCD) identifies the OOP classes that will be needed for the system.
The set of design classes includes problem domain classes, view layer classes, sometimes separate data access classes, and utility classes.
Problem domain classes are derived from classes that were identified during analysis activities hence the name: (user need) domain classes.
The design classes include the class level variables that are needed for the class.
The classes also show method names of the important methods within each class.
These methods are identified and specified during high level design and detailed design.
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