Applied System Software

Prof. Aleksejs Jurenoks

Your total score depends on 3 factors:

• All works completed on time, observing ORTUS deadlines - 30%
• Two tests that will be evaluated with a mark - 30%
• Final exam in the Online environment - 40%.

relevant course: https://github.com/gabboraron/halado_szoftvertechnologiak

What is application and what is Software

requireeóments are constantly changing

Lifecycle

• conception
• childhood
• adulthood
• retirement

which activites should we select forthe software project? what are the dependencies between them? how should we schedule the activites?

funcional modeling of software lifecycl

• scenarios
• use case model

structural modeling of software lifecycle

• object identification
• class diagrams

dynamic modeling of software

questions:

• What is the problem?
• what is the solution?
• what are the best mechanisms to implement? - languages/API
• how is the solution constructed? -
• is the roblem solved?
• can costumeruse the slution?
• how dowe deal with changes?

soft dev activities:

• requirements
• system design
• detailed design
• program implenetation
• testing
• delivery
• maintenence

waterfall model to vmodel

concept proposal of a New text editor software system

concept_proposal.doc

requirement analysis

bridging gap between system requirements enineering ad software design

• sstem information
• function
• behavior

model -> data

objectives:

• identify customer's needs
• evaluate system for feasibility
• perform economic and technical analysis
• allocate functions to system elements
• estabilish schedule and constraints
• create system definitions

software requirements analysis phases:

1. problem recognition: what do you want to solve
2. evaluation and synthesis: how it is implemented, what kind of models do we used for
3. modeling: how and what system can handle it?
4. specification
5. review

management questions:

• how much effort put towards analysis?
• who does the analysis?
• whhy is it so difficult?
• who pays for it?

feasibility study:

• economic feasiblity: cost benefit analysis
• technical: hardware/software/people
• legal:what acan we do, GDPR, etc
• alterantives: there is always more than one way to do it

system specification:

• functional data tdescription
• subsystem description
• system modeling and simulation results
• products
• appendices

requirements:

• features of system or function used to fulifill system purpose
• focus on user's needs and not on solution

types ofrequirements:

• functional
  • input/output
  • processing
  • error handling
• non functional requirements
  • physical enviroment
  • interfaces
  • user/human factors

requirement definition:

• general purpos of document
• system background and objectives
• description of approach
• detailed characersitics

software requirements elicitation

• customer meetings are most commonly usued
• context free

*FAST

• fascilitated application specification technque
• meeting between customer and dev at neutral site
• gals:
  • identify probelem
  • propose elements of solution
  • negotiae different appproaches
  • specify preliminary set of requirements

QFD

• quality function development
• customer's needs impply technical requirements:
  • normal requirements
  • expected requirements
  • exciting requirements

use cases

• scenraios that describe how the product will be used
• written narratives that describe the role of an actor
• use cass designed from the actor's point of view
• not all actors can be identified during the fst iteration of requirements
• identify the firs actors feore creating the first use-cases

profiels:

• full control: administrator
• read/write/modify all manager
• read/write/modify own inspector
• read only

information domain

• encompasses all data objects that contain numbers text images audio or video
• content/data model
• information flow
• information structure

modelling

• data model
• functional model
• behavioral model

specificrepresentation

• representation format and content
• information contained within the specification should be nested
• diagrams and other noational forms should be restricted in number and consistent use

specfication

• conducted by custemer and software developer
• once approved the specs becomes a contract for software development
• the specification is difficult to test in a meaningful way
• assessing the impact of specification changes is hard to do

User Interface Analysis and Design

ex: how MS Word communicate with MS Excel

text based interface simplifes the interaction; easyer to teach

user interface development - spiral process

• Interface analysis (user, task, and environment analysis)
  • Focuses on the profile of the users
  • Concentrates on users, tasks
  • Studies different models of system function
• Interface design: set of interface objects and actions
• Interface construction begins with a prototype that enables usage scenarios
• Interface validation

based on user:

• Define interaction modes
• The user shall be able to perform the same action via keyboard, mouse, voice recognition
• Allow user interaction to be interruptible and "undo"able
• allow the interaction to be customized
• Hide technical internals from the casual user
• Design for direct interaction with objects that appear on the screen

Reduce the User's Memory:

• Reduce demand on short-term memory
• Establish meaningful defaults
• Define shortcuts that are intuitive
• The visual layout of the interface should be based on a real world metaphor
• Disclose information in a progressive fashion

Make the Interface Consistent:

• The interface should present and acquire information in a consistent fashion
• Allow the user to put the current task into a meaningful context
  • able to communicate with the software;
• Maintain consistency across a family of applications MS Office - Word - Excel, PowerPoint, etc in one line
• If past interactive models have created user expectations, do not make changes unless there is a compelling reason to do so!

Models:

• User profile model – Established by a human or software engineer
• Design model – Created by a software engineer
• Implementation model – Created by the software implementers
• User's mental model – Developed by the user when interacting with the application

Analysis: if the interface fulfill the enviroments

• The users who will interact with the system through the interface
• The tasks that end users must perform to do their work
• The content that is presented as part of the interface
• The work environment in which these tasks will be conducted

user interface information can be obtained from

• User interviews with the end users
• Sales input from the sales people who interact with customers
• Marketing input based on a market analysis to understand how different population segments might use the software
• Support input from the support staff who are aware of what works and what doesn't

Work Environment: different UI on Win/Mac/ubuntu/android/ios

10 Usability Heuristics for User Interface Design

Security

http://www.ganssle.com/

Security vulnerabilites are to be cosdered bugs, the same way as a functional bug, and tracked in the same manner.

Factor some time into the project plan for security. Consider security as added value in an application.

application security risk categorization

• more security for riskier applications
• ensures that you work the most critical issues first
• scales to houndreds or thousands off applications

tools and methods:

• security profiling tools gan gather facts like size cpmplexity, security, mechanisms, dangerous calls
• questionnaire to gather risk informations: asset value, available functions, users, environment, threats
• risk based approach: evaluates likelihood and consequneces of successful attack

start the generic set of security requirements

• include all sec mechanisms
• address all common vulnerabilities
• should address driving requirements

tailoring examples

• specify how atentication will work
• detail the access control matrix
• define the input validation rules
• choose an error handling and loging approach

everybody tries to break your app!

assemble the tam:

• experts in technology
• secrity minded team
• do a high level pentest
• be sure to do root cause analysis on any flaws

how much request our system could have?

how do you control audit data?

desig configuration data for audit

Develop Security Test Plan

• SELECT and Establish the Test Target Clearly
• Select Test Environment
• Define Test Scope
• Determine Test Restrictions
• Determine Test Window Details
• Obtain Access Credentials
• Obtain Stakeholder Approval