Info sys in org Flashcards
IS • What is an information system?
◦ IS collects, processes, stores, analyses and disseminates information for a specific purpose ◦ Purpose is to get ◦ the right information ◦ to the right people ◦ at the right time ◦ in the right amount ◦ in the right format
Define the concept ’information system’.
◦ is a collection of interrelated components to complete business tasks i.e. hardware, software, people, procedures, input, output and data (Satzinger)
◦ combines IT, people and data to support business requirements (Shelly)
◦ consists of hardware, software, specific job roles, controls, users of the system, documentation and manual (Valacich)
◦ is a set of people, procedures and resources that collects data which it transforms and disseminates (Boddy)
◦ is used to add value, business value to resources (whether they produce goods or services or both)
Compare different characteristics of various information system definitions
“IS is a set of computer based tools for colecting, storing, and processing the data in our world.”
(ComputerBasedIS)An information system that uses technology to perform some or all of its intended tasks Not all information systems are computerized
Describe OUAS’s information systems as a case example.
Ouas uses IS oiva to communicate with students the important info, news, etc.OUAS uses Peppi to manage students’ courses, to allocate a certain number of students to a teacher, to track the students’ progress throughout the study curriculum.
SDLC:
Describe waterfall / traditional systems development method.
SDLC is the process of building, deploying, using and updating an IS.
The waterfall model was originally a model for software project development. It has been adopted and widely used for general systems design models due to its simplicity. The key idea of the waterfall model, as its name implies, is that system design systematically progresses from one phase to another, in a downward fashion. The process follows an iterative manner as well; that is, at any phase, the design can go back to its previous phase to adjust the design results based on the feedback received from the review. The stages are: Requirements and specs; Preliminary concept design; logical design; detailed design and tests; operational implementation; evaluation and modification; operational deployment
The advantages include:
The model is linear in nature, which makes it simple to understand. It is controllable, easy to manage due to the rigidity of the model. Works well for smaller projects where requirements are very well understood. Easy to document, assign tasks.
A limited amount of resources is needed to implement the model as the model clearly defines efforts and little interaction across stages is needed.
Provides a clear structure for system intermediate checkpoints and evaluations.
There are also some criticisms of the waterfall model. The main concern is also one of its benefits mentioned above: its simplicity and linear nature. Many believe that it is impossible for any complex design project to follow the waterfall model strictly; it is difficult to finish one phase completely before moving on to the next phase. For large, complex systems, it is not uncommon that users do not know exactly what they want at the beginning of system design. After seeing a number of prototypes, users usually change their requirements or add something new to them. System designers have little control over such changes, so lots of risk is involved. If these changes occur later in the waterfall model, the cost incurred could be tremendous and significant delays could result. It is apparent that the waterfall model is not flexible enough to accommodate constant changes, due to its rigid structure and lack of interaction between different phases.
Read stages tasks: https://www.tutorialspoint.com/sdlc/sdlc_waterfall_model.htm
Describe agile methods and agile system development.
The Agile development is an umbrella term used to describe a spec. group of methodologies that arouse out of a growing discontent with the way software dev. has been approached for the past 30 yrs. It itself is not a methodology but a set
of principles about how software should be developed. The agile manifesto: this manifesto is summed up in four key statements:
•Individuals and interactions over processes and tools
•Working software over comprehensive documentation
•Customer collaboration over contract negotiation
•Responding to change over following a plan.
A thing to note about the manifesto is that we emphasize working software over documentation, but that doesn’t mean that we don’t write documentation. We emphasize responsiveness to change over dogmatically following a plan, but that doesn’t mean that we don’t plan. The point is to pay more attention to the things that really matter. Paying attention to meeting the customer’s needs and creating correct software is more important than following the plan and writing the documentation, but it doesn’t mean that these other aspects don’t get any attention at all.
Methodologies are: ASD adaptive sof. dev., the crystal methodol., extreme programming, scrum, lean software dev…
Choose one of the agile approaches and describe its main tasks in each phase.
7 scrum practices:
The scrum master- ◦ primary responsibilities are to:
◦ Ensure that the Scrum practices are followed and that the values behind Scrum drive enactment of the process.
◦ Work with management and the customer to identify the individual who will take on the role of “Product Owner.”
◦ Facilitate each of the other practices
◦ Be the interface point among management, the customer, and the Scrum team
◦ primary importance are
◦ Communicating project status
◦ Removing impediments to progress
Product backlog-
◦ an evolving, prioritized queue of business and technical functionality that needs to be developed into a system
◦ sum total of the work that remains to be done on the project and includes everything from major features to bug fixes
◦ Any stakeholder in the project can contribute to the Product Backlog at any time, but it is the Product Owner who has the primary responsibility for determining the priority of backlog items
◦ The primary measure of progress in a Scrum project is the change in the number of items in the Product Backlog over time (growth in early sprints, decrearse later)
Scrum teams-
◦ commit to achieving a Sprint goal
◦ full authority to do whatever it decides is necessary to achieve the goal
Daily scrum meetings-
◦ meeting is where the team comes to communicate
◦ a short 15-minute meeting that takes place every working day
◦ where team members exchange information and others may come to listen —but not speak
◦ To keep the meeting short, all deliberation and discussion is relegated to meetings of interested people after the Daily Scrum
Sprint planning meeting -
◦ Customers, users, management, the Product Owner, and the Scrum Team determine the next Sprint goal and functionality
◦ Each 30-day Sprint begins with this planning meeting
◦ critical outputs of this meeting are
◦ Sprint Goal— The objective that is to be achieved during this Sprint
◦ Sprint Backlog— The subset of the Product Backlog that will be completed during the Sprint
◦ forum where lobbying and negotiation take place
◦ all stakeholders will have agreed to a Sprint Goal and Sprint Backlog
Sprint-
◦ a fixed period of time called a Sprint
◦ after the Sprint Planning meeting, the Scrum Team has full authority to complete the 30-day Sprint by doing whatever they feel is necessary
◦ during the Sprint, the team self-organizes and self-directs,
◦ sprint ends with the delivery of the promised executable product increment.
Sprint review-
◦ four-hour informational meeting
◦ the team presents to management, customers, users, and the Product Owner the product increment that it has built during the Sprint
◦ provides a concrete picture of the progress achieved during the Sprint and lays the foundation for the next Sprint Planning meeting
What is a use case diagram?
A description in the form of a diagram that shows how a certain system behaves when an one or more external users of the system interacts with it.
Describe the main components of use case diagrams.
Actors
◦ a role that a user can play while interacting with the system.
◦ provide input to the system and / or receive output from the system
Association
◦ Use cases are connected to actors through association relationships
◦ shows with which use cases the actors interact with
Use Case
◦ a major process that the system performs and that benefits an actor
◦ labeled using a descriptive verb–noun phrase
Relationships includes, and extends
◦ Behavior of a use case can be included in another
◦ Withdrawal depends on logging in (Logging in is included in withdrawal)
◦ Behavior of a use case can be extended with optional behavior
◦ Withdrawal can be extended with donation (Donation is extra optional behavior)
Subject Boundary
◦ used to separate a software system from its environment
Why are use case diagrams needed?
The main purpose of a use case diagram is to show who interacts with your system, and the main goals they achieve with it.
to communicate the desired structure and behavior of the system
◦ to visualize and control the system’s architecture
◦ to better understand the system
◦ to manage risk
THere are some things about a software system you canot understand unless you build a model
What is an activity diagram? Describe main components
An Activity Diagram is a behavioral diagram that shows the flow or sequence of activities through a system.
Shows: how activities/actions are completed. When are they completed. Where or by whom are they completed. Parallel activities. Decisions and conditions.
There are control nodes: initial node represents begining of a set of actions/ctivities.
Final activity node, used to stop process being modeled.
Actions and activities: represent either manual or PC behavuiour. Descriptive shoort name is given. Difference between an action and activity is activity can be decomposed further into a set of activities or actions. Action is non decomposable piece of behaviour being modeled.
Control flow - represents paths of execution (arrows)
Control Nodes
◦ Decision and merge nodes support modeling the decision structure
◦ Decision node is used to represent the actual test condition that determines which of the paths exiting the decision node is to be traversed
◦ Exiting paths must be labeled with a guard condition
◦ A guard condition represents the value of the test for that particular path to be executed.
◦ Merge node is used to bring back together multiple mutually exclusive paths that have been split based on an earlier decision (Often omitted)
Fork and join nodes
◦ Represent parallel and concurrent processes to be modeled
◦ Fork node is used to split the behavior of the business process into multiple parallel or concurrent flows
◦ Join node simply brings back together the separate parallel or concurrent flows in the business process into a single flow
Swimlanes / Partition (vertical / horizontal)
◦ Responsibility is assigned to objects or individuals who would actually perform the activity
◦ useful when modeling a business workflow
Object flows
◦ represents flow of objects (Dashed arrow)
◦ Activities and actions modify or transform objects
◦ show the actual objects that flow into and out of the actions or activities
Object Nodes
◦ Activities and actions typically modify or transform objects
◦ object nodes represent the flow of information from one activity to another activity.
Conditional threads, nested activity diagrams, partitions, are some of the advanced parts of activity diagram language
http://sparxsystems.com.au/resources/uml2_tutorial/uml2_activitydiagram.html
Why activity diagram is needed?
Used in business use process modeling etc. If an operation is complex, having a diagram with activities and actions helps in understanding.
to communicate the desired structure and behavior of the system
◦ to visualize and control the system’s architecture
◦ to better understand the system
◦ to manage risk
THere are some things about a software system you canot understand unless you build a model
What is UML?` How and why is it used?
UML a language for visualizing, specifying, constructing
and documenting the artifacts of a software-intensive
system
UML is only a language
◦ it’s process independent
◦ optimally it should be used in a process that is use case driven,
architecture-centric, iterative and incremental
UML is a language
◦ provides vocabulary and the rules for combining for the
purpose of communication
◦ tell, how to create and read well-formed models
◦ don’t tell, what models you should create and when
UML, a language for visualizing
◦ there are some things about a software system you cannot
understand unless you build models
◦ Some things are best modeled textually, others graphically
UML, a language for specifying
◦ specifying means building models that are precise,
unambiguous and complete
UML, a language for constructing
◦ models can be directly connected to a variety of programming
languages
◦ generation of code or reverse engineering
◦ Combining code generation and reverse engineering yields round-trip
engineering
UML, a language for documenting
◦ documentation of a system’s architecture and all of its details
◦ a language for expressing requirements and for tests
◦ a language for modeling the activities of project planning and
release management
Different UML diagrams
Activity -Procedural and parallel behavior
Class Class, -features and relationships
Communication -Interaction between objects, emphasis on links
Component -Structure and connections of components
Timing -Interaction between objects, emphasis on timing
Use case -How users interact with a system
UML can be used primarily in software-intensive systems
◦ UML is not limited to modeling software, it is expressive to model non-software systems
3 modes in using UML
◦ UML as a sketch
◦ Used to help communicate some aspects of the system
◦ Ideas, alternatives, discussion
◦ Rules not very important
◦ UML as blueprint
◦ Completeness
◦ Blueprints developed for a programmer to code up
◦ More sophisticated tool required
◦ Forward engineering
◦ Code generated
◦ Reverse engineering
◦ Source code read and generated to diagrams
◦ Sketches are used to explain how some parts in program work
◦ UML as programming language
◦ Diagrams drawn and compiled directly to executable code (UML becomes a source code)
UML is used because you can easily elaborate requirements of a system in the beginning of planning one. It is most useful if an executable model is created and running high abstraction code so the model becomes the code.
advantage of traceability across all stages of the software development lifecycle. Also, useful to creating a consistent, semantically correct model of application.
Describe different information system types:
TPS Transaction processing Processes transactions data from business events
FAIS Functional Area Information Supports activities within specific functional area
ERP Enterprise Resource Planning Integrates all functional areas of the organization
MIS Management information Produces reports summarized from transaction data
OAS Office automation Supports daily work activities of individuals and groups
BI Business intelligence
ES Expert Mimics human experts in particular area and makes decisions
DSS Decision support Provides access to data and analysis tools
TPS:
Transaction processing system
◦ supports the monitoring, collection, storage, and processing of data from the organization’s basic business
transactions
◦ Generates data to database
A transaction is any business event that generates data worth being captured and stored in a
database
A transaction is anything that changes the organization’s database
TPS
◦ collects data continuously, typically in real time
◦ critical to the success of any enterprise
◦ support core operations
◦ the most fundamental information system within organizations
◦ supports the entire organization
◦ functions primarily within a single organization
Millions and sometimes billions of transactions occur in large organizations every day
TPSs are inputs for other systems
◦ must handle data both in high volumes and in low volumes
◦ must avoid errors and downtime
◦ record results accurately and securely
◦ maintain privacy and security
organizations automate TPS data entry as much as possible
people or sensors collect the data
◦ entered into the computer via any input device
system processes the data
◦ batch processing
◦ data collected and placed in groups / batches, the prepared and processed periodically
◦ online transaction processing
◦ business transactions are processed online as soon as they occur
Describe various ways of acquiring an IS?
Once the need for a specific information system has been established, the system has to be acquired. This is generally done in the context of the already existing information systems architecture of the firm. The acquisition of information systems can either involve external sourcing or rely on internal development or modification. With today’s highly developed IT industry, companies tend to acquire information systems and services from specialized vendors.
There are several principal ways to acquire an information system from outside the organization. Many firms have resorted to outsourcing their information systems. Outsourcing entails transferring the major components of the firm’s systems and operations—such as data centres, telecommunications, and software development and maintenance—to a specialized company that provides its services under long-term contracts specifying the service levels (that is, the scope and the quality of service to be provided). In some cases the outsourcing entails moving the services abroad—i.e., offshoring in pursuit of the cost or expertise advantages. Responsibility for the acquisition of new applications then falls to the outside company. In other cases the company may outsource just the development or maintenance of their information systems, with the outside company being a systems developer.
Cloud computing is increasingly being adopted as a source of information services. It offers on-demand access via the Internet to services furnished by a provider that runs data centres with the necessary software and other resources. The services can be provided at one of three levels: as the infrastructure for running existing applications, as the platform for developing new applications, or as software-as-a-service (SaaS) to be used by the firm over the network. In particular, SaaS has become a cost-effective way to use enterprise systems. Generally, cloud computing is provided by external vendors, although some firms implement their own private clouds in order to share resources that employees can access over the network from a variety of devices, often including smartphones. Scalability and avoidance of capital expenditures are notable advantages of public clouds; the partial loss of control is a drawback.
Companies may choose to acquire an application by leasing a proprietary package from a vendor under a license and having the software customized internally or externally by the vendor or another outside contractor. Enterprise systems are generally leased in this way. An alternative is to deploy an open-source application, whose program code is free and open for all to modify under a different type of license that enforces the openness of the application in perpetuity. Generally, the costs of the use of open-source software include the technical support from specialized vendors.
> Internal information systems development
one of two broad methods is used: life-cycle development or rapid application development (RAD).Large organizational systems, such as enterprise systems, are generally developed and maintained through a systematic process, known as a system life cycle, which consists of six stages: feasibility study, system analysis, system design, programming and testing, installation, and operation and maintenance.
