1. Unit 191 Introduction to Software Engineering The objective of this section is to introduce the subject of software engineering. When you have read this section you will: understand what software engineering is and why it is important; understand what software development life cycle is; understand the various phases of the software development process.

2. Unit 192 Software engineering is a discipline: fault-free software, on time delivery, within budget, and satisfaction of the user’s needs. Software Engineering deals with: designing, building and maintaining software. Software Engineering

3. Unit 193 What is the life cycle of a civil construction? oThe civil engineer discusses with the customer and collects the requirements of the house. oHe plans and designs the model of house in a piece of paper. According to the civil engineering terminology, this model is called a blue print of the house. oHe constructs the house according to the design. oHe tests whether the house is constructed according to the plan. oHe hands over the new house to the customer which is now ready for occupation. Civil Construction Life Cycle

4. Unit 194 The SDLC has the same procedures of a civil engineering life cycle as given below: 1.Requirements phase 2.Design phase 3.Implementation phase 4.Integration phase 5.Deployment and Maintenance phase What is SDLC?

5. Unit 195 The system’s services, constraints and goals are established by consultation with the system users. They are then defined in detail and serve as a system specification. The specification document of the product is called Software Requirement Specifications (SRS) which constitutes a contract. Deliverables: SRS 1. Requirements Phase

6. Unit 196 The software requirement specifications (SRS) of a product spell out what the product is to do. The aim of the design phase is to determine how the product is to do it.  Architectural Design- The design team decomposes the product into modules, independent pieces of code with well-defined interfaces to the rest of the product. For each module, the designer specifies what it has to do and how it is to do it. The interface of each module, that is, the arguments passed to the module and the arguments returned by the module, must be specified in detail. This is called Architectural Design. Detailed Design- The the design team determines the internal structure of the product. Algorithms are selected and data structures are chosen. The internal data flows are determined. This is called Detailed Design. Deliverables: Architectural Design and Detailed Design. 2. Design Phase

7. Unit 197 During the Implementation phase, the various component modules of the design are coded and tested. The major documentation associated with implementation is the source code itself, suitably commented.  The job of testing the units or modules one by one independently is called unit testing. This is an integral part of implementation phase.  Deliverables: code. 3. Implementation Phase

8. Unit 198 4. Integration Phase The integration process involves building system combining the modules and determine whether the product as a whole functions correctly. There are two ways the modules can be integrated: 1.Top-down approach. 2.Bottom-up approach. Then the software is tested as a whole product which is called integration testing. Deliverables: the software product.

9. Unit 199  During the deployment phase, the software is installed and put into practical use. It also involves organizing training sessions for users. The users are trained with the user’s manuals. The user’s manual provides the installation documents, functional description of the software, reference guide with a list of error messages and possible causes and describe how to recover from detected errors etc.  Maintenance involves correcting errors which were not discovered in earlier stages of the life cycle, improving the implementation of system units and enhancing the system’s services as new requirements are discovered. 5. Deployment and Maintenance Phase

10. Unit 1910 Exercises  The sequential order of the phases of the SDLC is A.Requirements, Design, Implementation, Integration, Deployment and Maintenance phase. B.Design, Implementation, Requirements, Integration, Deployment and Maintenance phase. C.Requirements, Implementation, Design, Integration, Deployment and Maintenance phase  The modules of the project can be integrated using Top- down approach or __________.  The Deliverables of the Design phase (of SDLC) is ___________ and ____________.  The Deliverables of the Requirements phase is ___________.