The chapter describes Web engineering (WebE) as the process used to create high quality Web-based applications (WebApps). As WebApps become increasingly integrated in business strategies (e.g., e-commerce) the need to build reliable, usable, and adaptable systems grows in importance. Web engineering is not a perfect clone of software engineering, but it draws heavily on many of software engineering's principles and management activities. The Web engineering process begins with the formulation of the problem to be solved by the WebApp. The project is planned and the WebApp requirements are analyzed. Architectural, navigational, and interface design are conducted. The system is implemented using specialized languages and tools associated with the Web. WebApps tend to be highly evolutionary, so mechanisms for configuration management, quality control, and maintenance must be established early. Web engineering relies on formal technical reviews to assess the quality of the analysis and design models. Specialized reviews are conducted to assess the usability of the WebApp. Testing is applied to uncover errors in content, functionality, and compatibility.
WebApp Attributes
Network intensive
High concurrency
Unpredictable user loads
Performance (fast delivery)
High availability
Data driven
Content sensitive
Continuous evolution
Immediacy
Security
Aesthetics
WebE Application Categories
Informational (read only content provided with simple navigation)
Downloads (user downloads information from server)
Customizable (user customizes content to specific needs)
Interaction (community of users communicate using chat rooms, bulletin boards, or instant messaging)
User input (users complete on-line forms to communicate need)
Transaction-oriented (user makes request fulfilled by WebApp - places an order)
Service-oriented (application provides service to user, e.g., helps user determine mortgage payment)
Portal (application directs users to other web content or services)
Database access (user queries a large database and extracts information)
Data warehousing (user queries large collection of databases and extracts information)
WebApp Enabling Technologies
Component-based development (CORBA, COM/DCOM, JavaBeans)
Security (encryption, firewalls, etc.)
Internet standards (HTML, XML,SGML)
WebApp Development Process Characteristics
WebApps are often delivered incrementally
Changes occur frequently
Timelines are short
WebApp Process Framework
Customer communication
Business analysis - defines business and organizational context for WebApp
Formulation - involves stakeholders in gathering information needed to describe WebApp requirements
Planning
Plan consisting of task definition and timeline for the WebApp increment being developed
Modeling
Rapid analysis and design modeling tasks are adapted to WebApp
Models define the requirements and define the WebApp needed to satisfy them
Construction
WebE tools used to construct WebApp from model
Constructed increment is subjected to rapid tests to ensure errors (i.e., content, architecture, interface, navigation)
Delivery and evaluation
WebApp configured for its operational environment and delivered to end-users
Users evaluate WebApp in their environment and provide feedback to the development team
Increment is modified as required
WebE Analysis and Design Questions
How important is a Web site homepage?
What is the most effective page layout?
What media applications have the most impact?
How much work can we expect the user to do when searching for information?
How important are navigational aids in a complex WebApp?
How complex can input forms be without irritating the user?
How important are search and browse capabilities to the users?
Will the WebApp be designed to be accessible to users with disabilities?
WebE Task Set
Customer Communication (Analysis/Formulation)
Identify business stakeholders
Formulate business context
Define key business goals and objectives
Define information and applicative goals
Identify the problem
Gather requirements
WebE Planning
Define development strategy
Assess risks
Define development schedule
Establish metrics for content management and change control
WebE Modeling
Refine content classes
Identify content relationships
Refine user tasks
Identify computational functions
Identify database requirements
Refine interface requirements
Design the WebApp architecture
Design the interface
Design the navigational scheme
Design appropriate security and privacy mechanisms
Review the design
WebE Construction
Build or acquire the content and integrate it into WebAPP architecture
Establish navigational capabilities
Implement computational functions
Address configuration issues
Test all WebApp components
Address configuration issues
Test all WebApp components (content and function)
Test navigation
Test usability
Test security and performance
Test increment for different configurations
WebE Delivery and evaluation
Deliver WebApp increment to representative end-users
Evaluate end-user interaction
Assess lessons-learned and consider all end-user feedback
Make modifications to WebApp increment as required
Web Engineering Best Practices
Take time to understand the business needs and product objectives, even if WebApp details are vague.
Describe how users will interact with the WebApp using a scenario-based approach.
Develop a brief project plan.
Spend time modeling what you are going to build.
Review models for consistency and quality.
Use tools and technology that enable you to construct the system with as many reusable components as possible.
Don't rely on users to debug the WebApp, design comprehensive tests and execute them before releasing the system.
