SOFTWARE ENGINEERING 1 (PRELIMS)

System analysis

consists of activities that enable a person to understand and specify what the new system should accomplish

systems design

consists of those activities that enable a person to describe in detail how the information system will actually be implemented to provide the needed solution

System analysis and design

Plays an integral role in the development of an information system. Provides the tools and techniques needed as an information system developer to compute the development process

Project

a planned undertaking that has a beginning and an end and produces some end result. the activities required to develop a new system are identified, planned organized and monitored

System Development Life Cycle (SDLC)

a framework that identifies all the activities required to research, build, deploy, and often maintain an information system

SDLC Phases

Different projects might emphasize different parts of the SDLC or approach the SDLC in different ways, but all projects have elements of these four (4) phases.

Each phase is composed of a series of steps, which rely upon techniques that produce deliverables (specific documents and files that provide understanding about the project).

Planning

The fundamental process of understanding why an information system should be built and determining how the project team will go about building it

Project Initiation

the system's business value to the organization is identified. the system request and feasibility analysis are presented to an information systems approval commitee which decides wheather the project team will go about developing the system

Project Management

once the project is approved the project manager creates a work plan staffs the project and puts techniques in place and direct project through the entire SDLC

Analysis

it answer the questions of who will use the system what he system will do and where and when it will be use

Analysis strategy

It usually includes an analysis of the current system and its problems, and when to design a new system.

Requirements Gathering

The analysis of this information leads to the development of a concept for a new system. This concept is used to build a set of analysis models.

system proposal

It is a document combining the analyses, system concept, and models that are presented to the project sponsors who decide whether the project should continue to move forward. This is the initial deliverable that describes what business requirements the system should meet.

Design

how the system will operates in terms of hardware,software, and network infrastructure: user interface, forms and reports and the specific programs databases and files that will be needed

implementation phase

During this phase, the solution is transferred from paper to action, and the team configures the system and procures components for it.

system construction

The system is built and tested to make sure it performs as designed.

Installation

it is the process by which the old system is turned off and the new one is turned on

Establishment of support plan

It includes a formal or informal post-implementation review as well as a systematic way for identifying major and minor changes needed for the system.

The six core processess required in the development on any information system

1. Identify the problem or need and obtain approval to proceed with the project.

2. Plan and monitor the project - what to do, how to do it, and who will do it?

3. Discover and understand the details of the problem or the need - what is required?

4. Design the system components that solve the problem or satisfy the need - how will it work?

5. Build, test, and integrate system components. There will be lots of programming and component integration.

6. Complete system tests and then deploy the solution to satisfy the need

System development process or methodology

a set of comprehensive guidelines for carrying out all of the activities of each core process of the SDLC

Agile development

an information systems development process that emphasizes flexibility to anticipate new requirements during development

Iterative Development

an approach to system development in which the system is "grown" piece by piece through multiple iterations

Benefits of iterative development

- Portions of the system can sometimes be deployed sooner.

- By taking a small portion and developing it first, the most difficult problems can be identified and addressed early in the project.

- It makes the entire development process more flexible.

- It can address new requirements and issues that come up throughout the project

System analysis activities

-Gather Detail Information

-Define requirements

-Prioritize requirements

-Develop User-Interface Dialogs

-Evaluate requirements with Users

Gather Detailed Information

system analysis obtain information from people who will be using the system either by interviewing them or by watching them at work

Prioritize Requirements

once the system requirements are well understood it is important to establish which requirement are most crucial for the system

Develop User-Interface Dialogs

the user interface is all that matters thus developing user interface dialogs is a powerful method of eliciting and documenting requirements

Evaluate Requirements with Users

use an iterative process in which they elicit user input to model requirements return to the user for additional input or validation and then work alone to incorporate the new input and refine models

system requirements

all the activities the new system must perform or support and the constraints that the new system must meet (functional + nonfunctional)

Functional Requirements

relates directly to a process a system has to perform or information it needs to contain

Nonfunctional Requirements

required system characteristics other than the activities it must perform or support

usability requirements

describe operational characteristics related to users, such as the user interface, related work procedures, online help, and documentation.

Reliability Requirements

Describe the dependability of a system - how often a system exhibits such behaviors as service outages and incorrect processing and how it detects and recovers from those problems.

Performance Requirements

describe operational characteristics related to measures of workload, such as throughout and response time

Security Requirements

describe how access to the application will be controlled and how data will be protected during storage and transmission

Design Constraints

describe restrictions to which the hardware and software must adhere

Implementation requirements

constraints such as required programming languages and tools, documentation method and level of detail, and a specific communication protocol for distributed components

interface requirements

Describe interactions among systems

Physical Requirements

describe such characteristics of hardware as size, weight, power consumption, and operating conditions

supportability requirements

how a system is installed, configured, monitored, and updated

Stakeholders

people who have an interest in the successful implementation of the system

Internal Stakeholders

are those within the organization who interact with the system or have a significant interest in its operation or success

External Stakeholders

are those outside organization's control and influence

Operational Stakeholders

Are those who regularly interact with a system in the course of their jobs or lives.

executive stakeholders

are those who do not interact directly with the system but either use information produced by the system or have a significant financial or other interests in its operation and success

client

is the person or group that provides the funding for the project

organization's technical and support staff

include people who establish and maintain the computing environment of the organization

different ways to collect information about system requirements

- Interviewing users and other stakeholders

- Distributing and collecting questionnaires

- Reviewing inputs, outputs, and documentation

- Observing and documenting business procedures

- Researching vendor solutions

- Collecting active user comments and suggestions

Interview users and other stakeholders

is an effective way to understand business functions and business rules. o Time-consuming and resource-expensive option o Interview activities:

- Prepare detailed questions

- Meet with individuals or groups of users

- Obtain and discuss answers to the questions

- Document the answers

- Follow-up as needed in future meetings or interviews

Research vendor solutions

many problems may have been solved by other companies, provides new ideas cheaper and less risky, may purchase before really understanding the problem

Collect Active User Comments and Suggestions

User and other stakeholders perform the initial testing of systems function during the iteration in which those functions are implemented

Models and modeling

A representation of a system, process, product, structure, or environment

Reason of modeling

- Learning from the modeling process

- Reducing complexity by abstraction

- Remembering all the details

- Communicating with other development team members

- Communicating with a variety of users and stakeholders

- Documenting what was done

textual models

analysts use such model as memos, reports , narratives and list to describe requirements that are detailed and are difficult to represent in other ways

Graphical models

make it easier to understand complex relationships that are difficult to follow when described as a list or narrative

Mathematical models

system models that describes requirements numerically or as mathematical expressions

Unified Modeling Language (UML)

A language based on object-oriented concepts that provides tools such as diagrams and symbols to graphically model a system.

Workflow

a sequence of work steps that completely handle one business transaction or customer request

Activity Diagram

a UML diagram that describes user (or system) activities, the person or component that completes each activity, and the sequential flow of these activities

Synchronization bar

an activity diagram component that either splits a control path into multiple concurrent paths or recombines concurrent paths

Swimlane

an activity diagram component that divides the workflow activities into groups showing which agent performs which activity

Steps in creating activity Diagrams

1. Identify the agents to create the appropriate swimlanes.

2. Follow the various steps of the workflow and then make appropriate ovals for the activities.

3. Connect the activity ovals with arrows to show the workflow,