Download Quality Attributes of Web Software Applications – Jeff Offutt

Quality Attributes of Web Software
Applications – Jeff Offutt
By Julia Erdman
SE 510
October 8, 2003
Old time World Wide Web
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Originally designed to present
information in text documents
Simple framework
Became complex very quickly
Modern World Wide Web
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Large-scale software applications for:
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E-commerce
Information distribution
Entertainment
Collaborative working
Surveys
etc.
Modern World Wide Web cont.
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Diverse
Run on distributed hardware platforms and
heterogeneous computer systems
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Multiple programming languages and styles
Incorporates much reuse and third party
components
Cutting edge technologies
Must interface with users, other websites, and
databases
Diversity
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Diverse distribution and communication
Diverse components
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Interpreted scripting languages
Plain HTML files
Mixture of HTML with:
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Programs
Databases
Graphical images
Complex user interfaces
Creating a Website
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Engineering an effective website requires
large teams with diverse skills
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Programmers
Graphics designers
Usability engineers
Information layout specialists
Data communications & network experts
Database administrators
This results in Engineering a Website rather
than just creating a website
Web Software
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Unique aspects
Economic changes
Criteria for success
Technology changes
Unique aspects of Web
application software
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Diverse components
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Need to know how to integrate the diverse
components
Integrated differently from regular
software applications
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Source is often times not available
Executables may be on remote machine
Data transfer can occur from remote
sources
Economic Changes
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Quality of attributes
No financial motivation for quality
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“shrink wrap vendors”
Poor quality sooner than high quality later
Now must satisfy customer needs
Later but better
Criteria for Success
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Reliability
Usability
Security
And also,
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Availability
Scalability
Maintainability
Time to Market
Reliability
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Users expect web applications to work
There’s always another one out there
Usability
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Easy
Little site loyalty
Security
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Must avoid a breach of a company’s
website
Secure, secure, secure
Availability
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24/7/365
Downtime is costly
Diverse browsers
Scalability
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Increase number of users
Increase number of services
Small weakness are exemplified
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Reliability problems
Usability problems
Security breaches
Maintainability
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Frequent maintenance cycles
Compatibility
Reluctant to fix faults before release
Time to Market
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Important, but not as significant with
Web software applications
ALL of these attributes
have become important to
web software
Technology Changes
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First generation Web sites
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Client-server model
Static HTML files
Client-server model
Technology Changes
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Growth
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Commercial use
Full-fledged market channel for ecommerce
Interactive, highly functional systems
Early Internet
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Client-server model
Support only small websites
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Little security
Cannot support much traffic
Limited functionality
Modern Internet
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Fully functional software systems
Instead of Webmaster, a diverse team
lead by a Web manager is needed
Third-party software components and
middleware
Two-tier model not sufficient
N-tier Model
Modern Internet cont.
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N-tier model
Client-server connection still
Most of the software now resides on
separate computers rather than the
web server
Client -> web server -> application
servers -> database server
Benefits of N-tier Model
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New languages are easier to modify and
permit more reuse
Enhances maintainability, reliability, and
scalability
Additional security layers
Questions???
Works Cited
Offutt, Jeff. "Quality Attributes of Web Software
Applications", IEEE Software, Volume 19,
Issue 2, Mar/Apr 2002, pp. 25-32.