Requirement and Initial Analysis

Imam Bukhori, S.ST

Starting the Development Process

This module focusses on the following: Initiating a system development effort Analyzing the initial workflows Gathering information Creating a Problem Statement Creating Use Cases Introducing Component and Deployment

diagram

Gathering Information

You can gather information from several sources, including:

Customer’s initial requirement specification Domain Experts Customers and users Managers Input from marketing Previous projects

Avoiding Traditional Assumptions

You must avoid traditional assumptions, such as the following:

Users are naïve, developer know best Requirements are static You can build a correct solution the

first time Remember that projects evolve, and

customer requirements can change

Avoiding Traditional Assumptions

Do the following: Clearly identify the user’s requirements Ensure that your model can adapt to evolving

requirements Ensure that you can change your model

Domain Experts Refers to specialist in a particular area of

business Can be broadly subdivided into:

General domain experts Application-specific domain experts and

current business domain experts Similar business domain experts

Problem Statement Is document that clearly describes the

customer and system requirements for a project

Customer input is critical for this document Uses business domain language Has clear sentences, no jargon Contains details on project scope Specifies the context of the problem Specifies any known constraints

Key UML Diagrams

Use Case Diagram Shows who or what uses the system and

its feature Users of the features in a use case

diagram are called “actors” Use Case is shown as an ellipse For ease in modeling, Use Case diagrams

need to be prioritized

Problem Domain Refers to a statement that clearly identifies

new system-specific areas and problems Can be graphical or textual

Candidate Objects and Classes Identified from the Problem Statement Underline noun phrases from the Problem

Statement to build the list of candidate objects and classes

Sample ProblemThe Bay View Hotel requires a computer software package to facilitate the

automation of many manual tasks performed by the hotel staff. The package will be produced in several releases.

Release 1 covers the areas that are causing the most problems with the manual system. This document describes Release 1

ProblemThe hotel contains a number of hotel rooms available for hire to guest. The

information relevant to each room is :• Room number• Basic price• Maximum occupancy• Type of room (single, double, twin, executive, suite)The price of a room is the basic room price with any seasonal price adjustments

addedPotential guest can reserve one or more rooms for a specific period using the

telephone. These reservations are handled by the booking derks ( or departure date).

Simple ProblemA search is made for the availability ofrooms for the dates required. If successful, the customer is informedthe details and price.If accepted, a provisional reservation is made. This provisionalreservation is held for a duration entered by the booking clerk. Theprovisional reservation is modified to a firm reservation when adeposit payment is received and confirmed. This can be at the time ofthe initial reservation.The receptionist can also make a reservation for potential guests whoarrive without a reservation, the deposit payment must be made at thetime of initial reservation.It is noted when guests check in, at which time a specific room isassigned of the type required, and when the guest checks out.The room telephone is enable/disabled at checking/check outrespectively. This is done using a telephone call logging monitor.

Candidate Object and Class

Data Dictionary A document describing all the vocabulary

used in a project Entries are gathered with user interviews Stays for the entire length of the project and

the system Adds new terminology during the project Satisfies the need for a common vocabulary Assists in avoiding ambiguity Must be easily available to all project team Needs frequent, carefully controlled updates

Data Dictionary base Hotel Problem Room NumberA number that uniquely identifies a room within a hotel. The

starting digit indicates the floor on which the room is located. The range is from 1 to 780

Basic PriceThe flat rate price without any additional services or special deals.

Maximum OccupancyEach room has a specific number of guests that it can safely and

comfortably accommodate

Type of RoomA room type, for example, single, double, twin, or executive. The

room type depends on the size, position, furnishings, and additional facilities

Data Dictionary base Hotel Problem Check InWhen the guest arrives at the hotel and requests the allocation ofrooms reserved earlier.

Check OutWhen the guest leaves the hotel after settling the bill.

ReceptionistA member of the hotel staff specifically responsible for checkingin/out guests and making bookings for potential guests who arrivewithout an advance reservation.

Booking ClerkA member of the hotel staff specifically responsible for takingreservations.

Data Dictionary base Hotel Problem Provisional ReservationThe logging of a request for a specific number of rooms of a

specifiedtype, for a specified period of dates. Rooms will be held for thisreservation for a specific period. If no confirmation is obtained

withinthis period, the reservation will be canceled and the rooms will bemade available for reallocation.

Creating Use Cases A Use Case is a graphical and

schematic representation of a user’s interactions with a system

Assists in understanding system requirements and context

Graphically shown as an ellipse with solid lines

Creating a Use Case Model Comprised of several Use Cases Components are :

Actors Use Cases System Generalization and association

relationships

Sample Use Case Diagram

Sample Use Case add Actor

Sample Use Case with additional Dependency

Sample Use Case Diagram with New Extension Point

Use Case Scenarios Use Cases show a function from the user’s

perspective A scenario refers to one instance of a Use

Case Scenarios do not contain conditional

statements Begin the same way, but can end differently Major scenarios should be written Successful and unsuccessful paths through a

Use Case should be shown

Use Case Form To Write Use Case Scenario you need Use

Case Form Item of Use Case Form :

Name of the Use Case Actor involved Priority Status Extension points and includes Preconditions / Assumptions Post conditions Flow of events Alternative paths Performance Frequency

Sample Use Case Form

Activity Diagram

Show activities, processes, or workflows Are graphical Used anywhere you need to model

activities Modeling a Use Case is just one example

Activity Diagrams

Includes the following elements: Activities Decision Spilt of control Merge of control Iteration Object flow Swimlanes

Activity Diagram Notations

Sample Activity Diagram

Risk Assessment Need to asses risk areas for the project Use Cases can be the starting point for risk

assessment High risk Use Cases should be developed in

early iterations Risk can be in the following areas:

Requirements risk Technology risk Skill risk Resources risk Political risk

High-Level Package Diagram UML has notation to package any UML

elements ( classes, objects, Use Cases, incremental artifacts, and so on)

Notation similar to a folder icon Helps break down complexity Dependencies can be shown between packages Packages help in doing the following:

View the big picture without too much detail View small portions independently Create small portions to work in sections

Package Diagram Example

Sample High Level Architectural Package

Introducing Component Diagrams

Show components ( physical packaging of code )

Shows dependencies between components

Components can be nested Can be grouped into UML packages

Examples of Component Diagrams

Another Example Component Diagram

Introducing Deployment Diagrams

Show physical relationships between hardware components

Can be added at any stage Can be amended when additional

information is known Nodes can show components within

them Connection between nodes is shown

along with protocol

Example Deployment Diagram