Author, other info SCF Phase II [1] Seafront Cycle Route: Phase II.
New phase ii-2010
description
Transcript of New phase ii-2010
Mini Project-1
Phase – IIDesign Phase
Dept. Of Computer Science and Engineering
Objective
• Design allows an engineer to model the system or product that is to be built
• To produce a solution to a problem given in SRS document.
• To tell “how” a software system works.
Case Study: Guess the site!
• What is the single most important reason for this disaster?
•Design Flaw?!!!!
Why Design Is Important ?
• Design is the place where product (software) quality is established.
• A good design is
• understandable
• easy to implement
• reliable and
• allows smooth evolution
Good design is key to successful product
Poor design results to unstable system:
• Unstable System will fail when small changes are made.
• Unstable System will be difficult to maintain.
• Unstable System’s quality cannot be assessed until late in the software process.
What is it ?
• Design of the system is essentially a blueprint or a plan for a solution for the system.
• Design tells how the system is implemented.
• The design model provides details about software data structures ,architectures, interfaces and components that are necessary to implement the system.
Conceptual to Technical design
How to Design ?• A design process for software systems has
two levels
• Top – level design ( System design)
• Detailed design ( Logic design)
Top – level design
• System is a set of modules with clearly defined behavior which interact with each other in a defined manner to produce some behavior or services for its environment
• Decide which modules are needed for the system, the specifications of these modules, and how the modules should be interconnected.
Detailed Design
• In this level, the internal design of the modules, or how the specifications of the modules can be satisfied, is decided.
• It specify the processing logic and data structures so that the design is sufficiently complete for coding
Output of the Design Phase
• SDD (software Design Document) contain
• Different modules and Interfaces with each other.
• Data structures.
• Different classes and relationship between each other.
Deliverables : (Design documents)Top level design Detailed design
•Architecture
•Block Diagram •ER diagram
•Structure charts •Flowcharts/
Algoriths
•Data flow
diagram
Students need to do the
things which indicated in
green
•Class diagrams
Case study : Data flow modeling
• A restaurant owner feels that some amount of automation will help make his business more efficient .
Data flow diagram
Data flow Diagram
• For any known problem
Object oriented Modeling
• System is viewed as a set of objects• Objects interact with each other through the
services they provide• Object oriented systems are easier to build
& maintain• Object oriented design and implementation
is easy as objects are more stable than functions
Contd..
• UML (Unified modeling Language is used for OOM)
• -Class diagrams
• -Activity diagrams
• -Sequence diagrams
• -Deployment diagrams• Class diagrams are used to represent the
structure of the system
Class diagrams• Object (ask definition )• Class( ask definition ) • Services/ methods • Class diagram represent a structure of
the problem graphically using precise notation
Class name
attribute
operations
customer
Name:
Address:
Check_balance()
Credit_amt()
Relationship between different classes
• Generalization-specialization
• Aggregation
• Association
Generalization-specializationsymbol is used for representation. This shows inheritance property
example
Aggregation symbol is used for representation. This represents whole-part
relationship. If object is composed of many objects then aggregation is used
example
Associationshows static relation ship between different objects. Can be represented in different ways
cardinality
OO AnalysisFollowing steps are performed
• Identifying objects & classes
• Identifying structures
• Identifying attributes
• Identifying associations
• Defining services
Identifying Objects and classes
• Nouns represent entities in the problem space which will be modeled as objects
• Structures, devices, events, locations, organizational units are modeled as objects
• If the system does not need to keep information about some real-world entity or does not need any services from the entity, it should not considered as an object
Identify the structures
• Identify the hierarchies that exist between object classes
• Use generalization-specialization to represent inheritance
• Aggregation for whole – part relation ship
• Establish a relationship between objects using association
OO design
Problem description
Rough classes Class Diagrams
Noun identification technique
Specify associations
Example of drug storeask the students to identify the class, attributes,services
and relationships
How student should do ? Split each project batch into two sub batches in the first
week. Each sub batch has to do design independently. For
every SRS there will be two pre final designs accordingly.
The design done by one sub batch will be reviewed by the other sub batch and evaluator in the second week.
The group arrives at the final acceptable design combining the best from both the pre final designs.
The final design will be evaluated in the third week.
SRS Document
Pre final Design 2
Pre final Design 1
Final Design
Team Sub Batch 2
Divide Team into 2 Sub Batch es
Deliverables
• DFD
• Class diagram
• Algorithem/flowchart
• Data structures
• Files description(data file if exists)
schedule
Sl no Task Dates
1 Presentation on design phase and splitting of batches and assigning a design task
Week - 27th sept to 2nd oct
2 Pre-final design discussion with guide and team members
Week - 4th to 9th oct
3 Final design evaluation Week – 11th to 16th oct
Thank you