sdlc

System Analysis and Design : 

System Analysis and Design By S M Raza Fayaz Khan Diljan Wazir Amjad Hussain Azmat Qayum

Subsystems – part of larger systemSupersystem – larger system contains subsystemFunctional decomposition – dividing system into smaller subsystems and components : 

Subsystems – part of larger systemSupersystem – larger system contains subsystemFunctional decomposition – dividing system into smaller subsystems and components Definition of a System: A system is a set of interrelated parts working together toward a common goal. Systems analysis – what system should do Systems design – how components of information system should be physically implemented Systems analyst – uses analysis and design techniques to solve business problems with information technology

Slide 3: 

A symptom is an outward manifestation of a problem Pieces and ishikawa diagram helps in finding problem. A problem is a difference between what we have and what we want. PIECES P - the need to improve performance. I - the need to improve information (and data). E - the need to improve economics control costs, or increase profits. C - the need to improve control or security. E - the need to improve efficiency of people and processes S - the need to improve service to customers, suppliers, partners, employees, etc.

Slide 4: 

Decomposition : Systems Development Life Cycle ? Creeping Commitment ? Analysis Preliminary Investigation

Primary DeliverablesPreliminary feasibility reportGeneral problem statement : 

Primary DeliverablesPreliminary feasibility reportGeneral problem statement Next :Design Phase Key Activities Problem definition Estimate problem scope Estimate project feasibility Estimate resource commitment Go/no go decision Preliminary Investigation

Quality attributes: : 

Quality attributes: The Analysis Phase Gather information Define system requirements Logical model and physical model Prioritize requirements Prototype for feasibility and discovery Generate and evaluate alternatives Review recommendations with management System Requirements Functional requirements: Activities system must perform Nonfunctional requirements: Operating environment or Performance objectives Reliability, Performance, Security, Maintenance. Next: Design Phase

Slide 7: 

Design Phase The purpose of the design phase is to translate the “what” of the analysis phase to the “how” of new system development Logical DFDs and ERDs are created to guide in physical design. Custom development (build from scratch) Purchase and customize Outsource development Design Strategies Logical Design

Decomposition is the process of modeling the system and its components in increasing levels of detail.Balancing involves insuring that information presented at one level of a DFD is accurately represented in the next level DFD. : 

Decomposition is the process of modeling the system and its components in increasing levels of detail.Balancing involves insuring that information presented at one level of a DFD is accurately represented in the next level DFD. Data Flow Diagrams Design Phase

Slide 9: 

Design Phase Physical Design The Physical DFD Contains the same components as the logical DFD The same rules pertaining to balance and decomposition apply Contains additional details describing how the system will be built Steps to Create the Physical DFD Add implementation references Draw a human-machine boundary Add system related data stores, data flows and processes Update data elements in the data flows Update the metadata in the CASE repository

Slide 10: 

User Interface Structure Design The user interface defines how the system will interact with external entities The system interfaces define how systems exchange information with other systems The navigation mechanism provides the way for users to tell the system what to do The input mechanism defines the way the system captures information The output mechanism defines the way the system provides information to users or other systems Key Definitions Layout Content awareness Aesthetics User experience Consistency Minimal user effort Principles for User Interface Design

Slide 11: 

Implementation Types Server based Client-Server based Hybrid (combination of the above two) Network Models -Architecture Software Development Methods Custom development (build from scratch) Purchase and customize Outsource development A choice is made based upon project skills, time frame, business needs etc

Slide 12: 

Installation Conversion strategies: Direct: the new system instantly replaces the old Parallel: for a time both old and new systems are used. The old is abandoned when the new is proven fully capable Conversion Location Pilot conversion One or more locations are converted to work out bugs before extending to other locations Phased conversion Locations are converted in sets Simultaneous conversion All locations are converted at the same time

Slide 13: 

Corrective: identifying and correcting if something got off track. Adoptive: Making it upto date. Modifying features or upgrading to new changes and versions. Perfective: Adding new features and making basic changes like change in coding or the processes. Maintanance

Thanks. : 

Thanks.