Two Levels of Design
Broad design of the overall system structure
Also called General Design and Conceptual Design
Low level design that includes the design of the specific program details
Design of each use case
Design of the database
Design of user and system interfaces
Design of controls and security
Abstract Three Layer Architecture
Design the system interfaces
So other systems can talk to each other. System interfaces connect with other systems in many different ways:
- Save data another system uses
- Read data another system saved
- Real time request for information
- Software services
Relational Table Labelled
Components of design
Network and deployment architecture
Server based apps, mobile devices, PCs. All components must itegrate as a functioning whole
Screens and reports o devices connected to the system
Comm interfaces between other automated systems
Data structures, deployment methods.
Security and controls
Firewalls, Access, data protection in transit between devices. External, internal checks and measures.
abstract representation of the data flows, inputs and outputs of the system. This is often conducted via modelling. ER Modelling is commonly used.
have we spc in detail environment and options in which software will execute?
App architecture and software
Detail spec elements of software and how each use case is executed
Spec how system will comm with all other systems inside and outside the org
Spec how users will interact with system to carry out all their tasks? (Use Cases)
Spec in detail all info storage reqs
System controls and security
Spec elements to ensure system and data are secure and protected
Design the user interfaces
Dialog design begins with requirements, so use Use case flow of activities, etc
- Form Layout
- Look and feel
- Multiple interfaces (s/w, web, mobile)
- Multiple devices (laptop, touch, phone)
To the user, the interface is the system!
Process of defining and developing systems to satisfy specified requirements of the user.
Object-oriented analysis and design methods are becoming most widely used.
UML standard language in object-oriented analysis and design. Widely used for modeling software systems & increasingly used for high designing non-software systems and organizations.
Relates to the actual input and output processes of the system. How data is input into a system, how it is verified/authenticated, how it is processed, and how it is displayed as In Physical design, the following reqs about the system are decided:
1. Input requirement
2. Output requirements
3. Storage requirements
4. Processing Requirements
5. System control and backup or recovery.
Physical portion of systems design can generally be broken down into three sub-tasks: User Interface Design, Data Design, Process Design
Design the application architecture and software
1. Partition system into subsystems.
2. Define software architecture. Three layer or model-view-controller
3. Detailed design of each use case: Design class diagrams, Sequence diagrams, State machine diagrams
Issues when considering hosting
Reliability, security, physical facilities, staff, potential for growth
Design the Database
Architecture: distributed or central
Schema: Tables and columns in relational
Referential integrity constraints: Foreign key references – for linking tables
Uses domain model class diagram (or ERD)
Design the security and system controls
User interface controls
Transactions are “atomic”
No database anomalies
The architectural design of a system emphasizes on the design of the systems architecture which describes the structure, behavior, and more views of that system and analysis.
Design models (primary)
Nodes and locations diagrams
Design class diagrams
User interface screens and reports
System and security controls