Web Engineering and Technology

Unit I

Categories/Types of Web-Based Systems

Category Examples

Document centric Online newspapers, manuals

Interactive Registration forms

Transactional Online banking

Workflow-oriented Status monitoring, Business-to-Business solutions (B2B solutions) in e-commerce, e-government applications

Collaborative work Distributed authoring

Social web Discussion groups

Web portals Shopping malls

DownloadUser Input

Web Application Characteristics• Network

intensiveness

• Concurrency

• Unpredictable load

• Performance

• Availability

• Data driven

• Content sensitivity

• Continuous evolution

• Immediacy

• Security

• Aesthetics

Web Engineering

• WebE is the process used to create high quality Web-based applications (WebApps)

• WebE draws heavily on the principles and management activities found in software engineering processes

• Web Engineering is the application of systematic and quantifiable approaches (concepts, methods, techniques, tools) to cost-effective requirements analysis, design, implementation, testing, operation, and maintenance of high-quality Web applications.

Goals of Web Engineering

• Develop High Quality Web applications

– Effective

– Efficient

– Achieve desired application

• Maintain and evolve

– Plan for change – solution may change the problem

• Encourage the use of systematic, disciplined and quantifiable approaches and process models

WebE Process Overview

• Formulation of the problem• Planning• WebApp requirements analysis• Architectural, navigational, and interface design• System implementation using specialized

languages and tools associated with the Web• Configuration management, quality control, and

maintenance mechanisms are established early

Web Engineering Activities (1/3)

• Requirements specification and analysis• Web-based system analysis and design• Web development methodologies and techniques• Migration of legacy systems to Web environments• Web-based real-time applications development• Web-based multimedia application development• Testing, verification and validation techniques and tools• Quality assessment, control and assurance

Web Engineering Activities (2/3)

• Management of access to applications and privileges• Configuration and project management• “Web metrics” – metrics for estimation of development

effort• Performance specification and evaluation• Update and maintenance• Development models, teams, and staffing• Human and cultural aspects• User-centric development

Web Engineering Activities (3/3)

• Graphics, animation and streaming

• Copyright, legal and social aspects

WebE Process Model:

Formulation

• Goals and objectives– What is the motivation for the WebApp?

– Why is the WebApp needed?

– Who will use the WebApp?

• Informational goals – user's intention for using the content

• Applicative goals – ability to perform tasks within the WebApp

WebE Process Model:

Planning

• Estimate project cost• Evaluate risks• Define finely granulated schedule for first

increment• Define coarser schedule for subsequent increments

WebE Process Model:

Analysis

• Establishes requirements and identifies content items

• Content analysis

– content provided by WebApp is identified

• Interaction analysis

– use-cases developed to describe user interaction

• Functional analysis

– usage scenarios used to define operations and functions applied to WebApp content

• Configuration analysis

– WebApp environment described in detail

WebE Process Model:

Engineering

• Content design

• Production tasks

• Architectural design

• Navigation design

• Interface

WebE Process Model:

Page Generation and Testing

• Content and technical designs are merged to produce executable web pages

• Testing exercises WebApp navigation, attempts to uncover errors in applets/scripts/forms, and checks for environment incompatibilities

WebE Process Model:

Customer Evaluation

• Each increment of the WebApp is reviewed

• Changes required by customer are applied to next increment

Difference between SE and WebE - Agility

Main Reasons for not applying SE principles to WebE:• Business � strategies and rules change rapidly• Management demands near-� instantaneous – almost immediate

reaction• Responsiveness (even when such demands are completely

unreasonable).• Stakeholders often don’t understand the consequences of the

Web and keep changing their mind even as they demand rapid delivery

• An � agile approach helps cope with this fluidity and uncertainty

What is an Agile Process?

• „ Agile Web engineering combines a philosophy and a set of development guidelines. The philosophy encourages:

– „ customer satisfaction

– „ informal methods

– „ overall development simplicity

– „ early incremental delivery of the Web Application

– „ small, highly motivated project teams

– „ minimal work products

• „ An agile process stresses delivery over analysis and design (although these activities are not discouraged), and active and continuous

communication between developers and customers.

Activities

Web Engineering Software Engineering

Customer Communication Software Project Management

Planning Formal Technical Reviews

Modeling Risk Management

Construction Software Quality Assurance

Delivery and Feedback Measurement

Software configuration management

Reusability management

Work product preparation and production

Web Engineering Models

• Content Modeling

• Hypertext Modeling

• Presentation Modeling