ppt

An Agile Approach for
Web Systems
Engineering

A Presentation of an Article by V.E.S. Souza and R.A. Falbo

In the beginning. . .


Web sites were static HTML


More power! Server side dynamic sites!


1993 CGI


1994 PHP


1995 ASP


1996 Java Servlets


1999 JSP

Discovery of Business Value


Web applications are born


Value in anywhere access


Easy to deploy


No need to install software on client


O/S independent (for the most part)

Web Engineering


Ad hoc web app development in the beginning


Web engineering borrows many SE concepts


Has its own special set of models, methods &
technologies


Web Engineering Frameworks


Java


.NET


PHP


Faster and more productive development


Lends its self well to agile development

Rapid Development of Web Apps
Using Java & Frameworks


Identify business needs


Plan project


Generate requirements


Model


Implement


Test


Deliver


Allow end
-
user feedback & evolution


Requirements Specification


Model with a purpose


Use multiple models


Discard non long
-
term value models


Content before representation [not strict UML]


Know the models & how to use the tools

Design


Heavily dependent on the platform


WAE (web application extension of UML)

WAE
-

UML

Presentation logic layer


Classes that are for the UI (web pages)


Controls the interaction (controller package)


Controller classes receive user input from the
view call system functions (application package)
and return the control to the view to display the
results

Business Logic Layer


Application Package (intelligence that was
defined in use cases, create, retrieve, update and
delete domain package objects)


Domain Package (represents business domain
concepts identified in requirements)

Data Access Layer


Store persistent objects in long
-
term duration
media such as databases


Advocate use of DAO design pattern


Decouples the data access logic from the
database




Frameworks recommended by the authors

Object/Relational mapping
framework


Hibernate


http://www.hibernate.org/


Allows us to thing in terms of an object and its
properties rather than a certain set of fields . e.g.
person.firstName = Fred rather than INSERT INTO
peopleTable.firstName Fred, not being concerned with
the SQL taking place behind the scenes.


Allows expression of queries in a SQL extenstion called
(HQL), native SQL, or an OO
Criteria and Example
API
.

Controller Component


WebWork


http://www.opensymphony.com/webwork/


Reusable UI templates, form controls, UI
themes, form field validation, form
parameter
mapping to JavaBeans

View Component


FreeMarker


http://freemarker.sourceforge.net/


Allows web designers to work in parallel with
programmers


A generic tool that generates text output from
templates


SiteMesh


http://www.opensymphony.com/sitemesh/


Web page decoration and layout framework


Used to keep a consistent layout throughout all pages

All Layers


Spring Framework


http://www.springframework.org/


Performs dependency injection to integrate the
different packages


Acegi Security integrated with Spring


http://www.acegisecurity.org/


Performs authentication and authorization
services for both controller and application
packages.

Conclusion


The creation of agile processes for web
development is promising


The agile approach we use in traditional SE can
be adapted for engineering of web applications.


Web applications need to be developed that can
help refine an agile approach to web engineering


The frameworks that are out there need to be
evaluated further for their applicability to such
an approach

Citation