Software Engineering
Chapter1:intro
- software=computer programs + associated documentation
software we need methods to develope high-qualified software:
- standard
- systematic
- efficient
- dependable
- easy-to-use
- software engineering is an discipline that is concerned with all aspects of software production from initial conception to operation and maintenance.
- History of software engineering:
SE's composition:
software development(needs methods, techniques and tools to support)
- requirements engineering
- software design
- coding
- testing
- maintenance
- project management
- structured and object-oriented
software engineering ethics
- confidentiality
- competence
- intellectual property rights
- computer misuse
Chapter2:software process model
Organization of processes and activities
Key points in this chapter:
- What is software process?
- What is software process model?
- What are the software process models and what's their advantages and disadvantages and implementation area?
- Difference between plan-driven and agile?
- What is agile method?
- What are the steps of software process?
Software process
fundamental activities (all processes involve the following steps)
- Specification:what the system should do
- Design and implementation:the organization of system
- Validation:checking if it does what the customer wants
- Evolution:changing in response to customer need
Process descriptions
- Products
- Roles
- Pre- and Post- conditions
- software process:a sequence of activities leading to the production of a software product.
- software process model/aka product life cycle : abstract representation of software process.
process description of software process model
- products
- roles
- Pre and post conditions
software process model(des and where)
- Plan-driven processes:Plan-driven processes are processes where all of the process activities are planned in advance and progress is measured against this plan.
- Agile processes:In agile processes, planning is incremental and it is easier to change the plan and the software to reflect changing customer requirements.
Kinds of software process models:
Waterfall model:Plan-dirven strict order
- requirements definition
- system and software design
- implementation and unit testing
- integration and system testing
- operation and maintenance
Advantages:
-
Disadvantages: difficult to deal with changing requirements
Application domain:
- Large system
- requirements that are well-understood and unlikely to change radically
Incremental model
interleaving activities
Advantages:
- dealing with change
- repid delivery
- effective feedbacks
Disadvantages:
- invisible processes
- degrading system structure
application condition:
- limited time and budget
- changing requirements
Incremental model:
- Extreme programming
- Scrum
- Crystal
- Adaptive software development
- DSDM
- Feature driven development
Scaling agile mothods：
- Scaling up
- Scaling out(pipeline)
Reuse-oriented model
conponent search and configuration
Key points of re-use oriented model:
- Component selection
- Component filtering
- Component-dependent requirements development
Advantages:
- Reduce cost and risk
- faster delivery
Disadvantages:(用的是别人的component 那肯定会有一些缺点)
- inevitable requirements compromises
- different from real needs
- components out of control
- Agile methods
Agile不是一个software process model
Chapter 3:requirements engineering
requirements engineering 是为了得到好的requirement
what should the system do?
key points in this capter:
Requirement
- Functional requirement
- Non-functional requirement
What is not in requirements:
- design or implementation details
- project planning information
- testing information
Requirements Engineering Composition
- Requirements Elicitation(找到有哪些requirements)
Process of identifying the needs and constraint of stakeholdes for a software system.
Requirements elicitation is a complex process that consists of gathering, researching, defining, structuring, and clarifying a product’s requirements. As a result of elicitation, a BA creates a set of project objectives.
Requirements Analysis（分析找到的需求）
- Use analysis model as graphical representation
- Requirements Specification
The product's detailed functional and non-functional requirements reside in a software requirements specification.(SRS)
- Requirements Validation
Feasibility study
- Purpose
- Mission
Requirements Analysis Models
State-Transition Diagram (STD)
Describes how the system transferred among different states.
Usage:
- Useful for specification review or test case generation
- Not suitable for data-intensive systems
Data Flow Diagram (DFD)
How data flows among different system modules.
Process: must get inputs and then produce outputs (immediately)(compare with CDFD)
DFD可能会有很多层级 Hierachy:interface of high level should be consistent with the low one
Usage of DFD:
- Useful for transaction-intensive systems.
- Lack of explicit data relationships.
- Cannot demonstrate temporal features.
- Not appropriate for control systems.
- Entity-Relationship Diagram (ERD)
Commonly used data model.
- Dialog Map
- Decision Table
- Decision Tree
- Use Case Diagram
- Class Diagram
- Activity Diagram
Requirements Specification
- The product's detailed functional and nonfunctional requirements reside in a software requirements specification (SRS).
Who need SRS:
- User
- Customer
- Project manager
- Analyst
- Developer
- Tester
Attributes of good SRS
- Well-structured
- Abstract
- Complete
- Easy to understand
- Unambiguous
- Verifiable
Requirements Specification
- Natural language
- Graphical models
Formal specification
Data definition in formal specification
- Primitive data elements(No further decomposition is possible or necessary)
- Composition(Multiple data items)
- Iteration(Multiple instances of one item)
- Selection(Limited number of discrete values)
Formal specification(methods?)
- B,Z,VDM
- SOFL(Structured Object-oriented Formal Language)
Requirements Validation
Does the specification satisfy user's requirement?
3 main parts: prototype,review and testing
Software prototype
Pros of software prototype:
- Making it alive.
- Easy to be understood by non-experts.
- Fast.
- Closes gaps in customer's understanding of the requirements.
- Stimulates customer's thinking.
- Early feedbacks.
- Deals with variability.
Types of software prototype:
根据description分类：
- Horizontal
Does Not dive into all the layers or into system details
Demonstrate how the user interacts with the target system
- Vertical
Touches on all levels of the system implementation
Looks like a subsystem of the target software
- Horizontal
根据purpose分类：
- Throwaway
For answering questions and resolving uncertainties
Discard or being integrated into the final system
- Evolutionary
A solid architectural foundation
Must be built with robust, production quality code
Takes longer time
- Throwaway
Building tools of software prototype
- Paper:Cheap,Fast,Anytime,Hardly any interaction,Throw away
- Software:Tool selection,Interactive behaviors,Maybe used as part of the real system
- Animation:Evolutionary prototype
Software review(another kind of documentation)
- peer deskcheck: ask one colleague to look over my work.
- passround:invite several colleagues to examine a deliverable concurrently.
- walkthrough:author describes a deliverable and solicits comments.
The 3 types(peer,passround and walkthrough) lack engineering guidelines and controllable processes
inspection
Best-estabilished type of formal peer review.
Inspection Roles:
- Author
- Moderator
- Reader
- Recorder
defect checklist(在review里还是单独的一个部分？)
- Organization and Completeness
- Correctness
- Quality attributes
- Special Issues
challenges in review
- Large requirements documents
- Large inspection teams
- Geographical separation of inspectors
Testing(validation of software)
- For detecting missing, erroneous, or unnecessary requirements
- Generate test cases
- Walkthrough the specification with the test cases
- Result analysis
Chapter 4:software design
requirements specification: what
design specification:how
software design definition:
A description of the structure of the software to be implemented, the data models and structures used by the system, the interfaces between system components and, sometimes, the algorithms used.
Software design：
- Architectural design: Design Patterns and Priciples
- Detailed Design:Strategy, Methods and Tools
Architectural design
Designing the overall structure of the system.
A model that describes how the system is organized as a set of communicating components
Design Patterns
Each pattern provides a solution for a kind of design problems under certain conditions
Knowledge reuse o Written in natural language
- MVC pattern
Application architectures
Design principles
- Abstraction
- Refinement
- Information hide
- Modulization
- Module independence
Cohesion:operation in one module(deep degree)
- Coincidental Cohesion
- Logical Cohesion
- Temporal Cohesion
- Procedural Cohesion
- Communicational Cohesion
- Functional Cohesion
- Informational Cohesion
Coupling:different modules(light degree)
- Content Coupling
- Common Coupling
- Control Coupling
- Stamp Coupling
- Data Coupling
- Good design has high cohesion and low coupling.
Tools for architectural design
- Hierarchy chart
- HIPO(Hierachy plus Input-Process-Output)
Detailed design
- Flowchart
- Problem Analysis Diagram(PAD)
Chapter 5:software testing
Software testing definition
A set of activities for identifying failures in a software or system to obtain user satisfaction.
Definitions
- Test case：A set of input values + execution pre-conditions + expected output + execution post-conditions
- Test case instantiation：(ppt是不是错了？)
Test oracle：
- Mechanism
- Matamorphic
Testing levels
Unit/Component testing
Features:
- Testing on components
- Applicable to a piece of independent program
- Usually with source code
- Identified defects are directly fixed
- Discovering errors at an early stage
- Diver:
- Stub:
Integration testing
- Big Bang integration
- Top-Down integration
- Bottom-up integration
- Sandwich integration
Acceptance testing:Obtain customer or user acceptance of the software
- User acceptance
- Operational acceptance
- Contractual acceptance
- Regulatory acceptance
- Alpha test
- Beta test
- Test Case + Test Oracle
- Metamorphic Testing F(x)=sinx的example
- Test case extantiation
Different testing levels:
Unit/Component testing
- Driver和Stub 越简单越好
Integration testing
- Big Bang integration
Top-Down integration
- Low-level components not fully tested
- Problem: defensive programming
- Bottom-Top intergration
Acceptance testing
- User acceptance
- Operational acceptance
- Contractual acceptance
- Regulatory acceptance
Software testing methods
White-box testing
Can access source code/inner structure of program, base the test cases on the inner structure of the software program.
Static analysis: Test without executing
- NULL pointers
- Use of uninitialized data
- Incorrect usage of APIs
- Buffer overruns
- Error handling issues
- Unreachable code
Dynamic analysis: Test while running (Usually used for unit testing)
- Statement coverage: Designing test cases that enable the execution of each statement at least once.
- Branch coverage: Designing test cases that enable the execution of each branch of each decision at least once.
- Clause coverage: Designing test cases that enable each clause to evaluate to each possible value.
- Combinatorial coverage: Designing test cases that enable the coverage of each possible combination of the clauses of each decision.
- Active clause coverage(Same as MCDC)
- Path coverage:
Graph coverage:
- Node coverage
- Edge coverage
Black-box testing
Input space partitioning
- IDM(Input Domain Modeling) approach
- Interface-based
- Functionality-based
- Boundary value analysis
Different techniques for different specification languages
- Finite state machine
- UML
- Scenario-based
- Z,B,SOFL
Tool support for black-box testing
- Test case generation
- Expected result generation
- Grey-box (不深入讨论)
Chapter 6:object oriented software development
Object oriented
Object(对象)
An entity with a well-defined boundary
and identity that encapsulates state and behavior.
Class(类)
A set of objects that share the same properties and behaviors.
Inheritance(继承)
Message
A specification of a communication between objects that conveys information with the expectation that activity will ensue.
Abstraction(抽象)
- Emphasizes relevant characteristics
- Suppresses other characteristics
Encapsulation(封装)
Polymorphism(多态)
Different implementation behind a single interface.
Object-oriented analysis and design
UML(Unified Modeling Language)
- Class diagram
- Use-case diagram
The context of the system to be built and the functionality provided by that system.
- Sequence diagram
Object-oriented testing:
Individual class testing
- Random
- Partition testing(state,attribute,function)
- Integration testing