1. Introduction to Software Engineering 1. Software Engineering Failures – Complexity – Change 2. What is Software Engineering? – Using engineering approaches to constructing quality software with a limited budget and a given deadline in the context of constant change – Activities Modeling activity Problem-solving activity Knowledge acquisition activity Rationale-driven activity

2. Modeling Focusing relevant details at each development stage A model is an abstract representation of a system for answering questions about the system Real world system: a set of phenomena Problem model: a set of interdependent concepts describing those aspects of the real world relevant to the problem under consideration. Model of problem domain vs. model of solution domain OO methods: Problem D. model + Solution D. model 1Objects and relationships in problem domain 2Object and relationships in solution domain (extension from 1) Software Development: identify and describe a system as a set of models to address the end user’s problem.

3. Problem Solving Software engineering is an engineering activity Rely empirical methods to evaluate the benefits of different alternatives represented as models The engineering method: 1. Formulate the problem (requirements elicitation and 2. Analyze the problem analysis) 3. Search for solutions (system design and 4. Decide on the appropriate solution object design) 5. Specify the solution (implementation) Activities: experimentation, pattern reuse, incremental evolution, reviews of problem and solution models

4. Knowledge Acquisition In modeling application and solution domains –Data collection –Information organization –Knowledge formalization Non-linear knowledge acquisition –Single piece of data can invalidate complete models –Linear software development process Water fall model –Non-linear software process Risk-based development –develop higher risks first Issue-based development –Develop all issues in parallel

5. Rationale Driven Rationale of the system –The context and rationale in which each design decision was made –To be captured and understood by software engineer –Represents a set of issue models with larger amount of information than the solution models –Not explicit (without explicitly evaluating different alternatives) –Enables software engineers to understand the implication of a proposed change when revising a decision. Rationale management

6. 3. Software Engineering Concepts Participants and Roles –Role a set of responsibilities associated with a set of tasks assigned to a participant typical roles: end user, client, developer, project manager –Participant any persons involved in the project plays certain role(s) Systems and Models –System: the underlying reality example: ticket distributor for a train –Model: any abstraction of the reality example: requirement, analysis, design, implementation models

7. Work Products –Artifact produced during development –Internal work product for the project’s internal consumption any artifact not in the contract or requested by the client example: test plan – Deliverable for the client defined prior to the start of the project and specified in the contract. Activities, Tasks, and Resources –Activity or phases: a set of tasks for a special purpose such as requirement elicitation –Task: an atomic unit of work in terms of management, to be assigned to a developer. –Resources: assets to be used to accomplish work.

8. Goals, Requirements and Constraints –Goals a high level principle to guide the project define the attributes of the system that are important primary goal and other goals of a project conflicting goals –Functional requirements area of functionality that the system must support –Nonfunctional requirements constraints on the operation of the system examples: performance, reliability, security

9. Notations, Methods, and Methodologies –Notation a graphical or textual set of rules for representing a model Example: UML for OO modeling, Z for system spec. –Method A repeatable technique for solving a specific problem Example: sorting algorithm, version control –Methodology a collection of methods for solving a class of problems decompose software process into activities examples: Unified software development process, Object Modeling Technique, Catalysis.

10. 4. Software Engineering Development Activities Requirement elicitation (Client and Developer) –The client and developers define the purpose of the system –Result: description of actors and use cases for functional requirement –Example Use case name:PurchaseOneWayTicket Participating actor:Initialized by Traveler Entry condition:1. Traveler stands in front of the ticket distributor at a station Flow of events:2. Traveler selects the source and destination stations 3. TicketDistributor display the price of the ticket 4. Traveler inserts sufficient money 5. TicketDistributor issues the ticket and returns change Exit condition:6. Traveler holds a valid ticket and the change Special requirements:If the transaction is not completed after 1 minute of inactivity, TicketDistributor returns all inserted money

11. –Nonfunctional requirements Reliability: The ticket distributor should be available to traveler at least 95% of the time Performance: The ticket distributor should provide feedback to the traveler within a second after the transaction has been selected. Analysis (Developer) –produce a model of the system that is correct, complete, consistent, unambiguous, realistic, and verifiable. –transform the use cases into an object model that completely describes the system –discover ambiguities and inconsistencies

12. System Design (Developer) –define the design goals –decompose the system into smaller subsystems that can be realized by individual teams. –Select strategies for building the system –results: strategy descriptions subsystem decomposition deployment diagram Object Design (developer) –define custom objects to bridge the gap between the analysis model and the system design platform Implementation –translate the object model into source code

13. 5. Managing Software Development Communication –exchange models and documents –report the status of work products –provide feedback on the quality of work products –raise and negotiate issues –communicate decisions –common convention and tool based Rationale management –the problem addressed –alternatives considered –evaluation criteria used –debate, consensus, and decision –difficulty: update and maintenance

14. Testing –find differences between the system and its models by execution with sample data –Unit testing compare the object design model with each object and subsystem –Integration testing compare the integrated subsystems with the system design –System testing compare the system with the requirement model by running typical and exception cases

15. Software Configuration Management –the process that monitors and controls changes in work products –Example changes requirement changes –client new feature –development new/improved understanding platform changes –new technology available system changes –fault and repair –enable developer to track changes configuration items to be individually revised versions for evolution of configuration items and roll back –enable developers to control change define baselines assess and approve increments from the baselines

16. Project management –oversight activities to ensure the delivery of a high-quality system on time and within budget –plan and budget the project during negotiation with the client –hire developers and organize them into teams –monitor the status of the project –intervene when deviations occur Software life Cycle –A general model of the software development process