Transcript Reusable Development Components from the Java(TM) 2

Reusable Development
Components from the
Java(TM) 2 Platform,
Enterprise Edition (J2EE(TM))
and Open Source Projects
Rob Weaver
Architect
Quovera
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Overall Presentation Goal
or Primary Purpose
Building reusable development
components helps us decrease time
to market and increase software
quality.
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Learning Objectives
• As a result of this presentation, you will
be able to:
– Understand “real world” reusable component
development
– Know about some of the strengths and
weaknesses of reusable code
– Learn some best practices.
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Qualifications
•
Quovera (formerly Millennia Vision Corporation)
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Experience
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Consultants with 10+ years experience
Over 200 clients for whom we have completed over 300
projects
Differentiators
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Founded in 1995 as “Millennia Vision Corporation (MVC)”
Strong High-Tech Industry Background
Profitable 5 Years Without Outside Funding
Architecture Technology Office (ATO)
Program Management Office (PMO)
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Qualifications
• Rob Weaver is a Web Architect for Quovera
– Member of Quovera’s Architecture and
Technology Office.
– Proponent of the web since 1995 when he
joined Excite to become a webmaster.
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Qualifications
• Will Andrews
– Technical Director for Quovera
– Member of Quovera’s Architecture and Technology
Office.
– Has been web enabling applications since 1997 at
PricewaterhouseCoopers.
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Reuse: the Holy Grail of software
development
• We can be freed from making the same
mistakes over and over again, and happily
pursue finding entirely new ones.
• Reuse is one of the benefits of an object
oriented language because OO is built
around it.
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Agenda
• Introduction
• Example of using reusable components
• Design decisions and patterns
• Reference Framework
• Challenges
• Summary
• Q&A
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Reusable code – more design,
less development
• Architecture and Technology Office Modeled
Systems (ATOM)
• Reference Framework Architecture
– Technologies
– Reusable Components
– Additional Services
– Layers
– Design Pattern Information Flow
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Reusable code – more design,
less development
• Open Source projects
– Open source components need to be well
understood
• Design considerations
– Keep framework lightweight
– Components need to be flexible
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Open Source projects
• Apache (http://www.apache.org/)
• Tomcat (http://jakarta.apache.org/)
• Struts (http://jakarta.apache.org/)
• JDOM (http://www.jdom.org)
• Netbeans (http://www.netbeans.org/)
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Design considerations
• Keep framework lightweight
• Components need to be flexible
• Open source components need to be well
understood
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Agenda
• Introduction
• Example of using reusable components
• Design decisions and patterns
• Reference Framework
• Challenges
• Summary
• Q&A
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Eating our own dog food
Quovera Time and Accounting
• Secure web-deployed time and expense (TimeX) reporting module
– Mission-critical for a consulting company
– Replace Excel solution
• Easy to use
• Leverages reusable components
– Database design
– Back-end PL/SQL utilities (email, user security, etc.)
– Java classes
• Fast
– Light-weight client
– High availability
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Design Decisions
• JSP solution
– Fulfills high-availability, fast, web-enabled
requirements
• Base the system on Quovera ATOMS and
Reference Framework
– Architecture and Technology Office Modeled
Systems
• Uses Model-View-Controller architecture
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Model-View-Controller (MVC)
• SmallTalk strategy recently promoted by
Sun
• Model = data and values, validation, ranges
• View = display
• Controller = what happens
when user interacts with
the component
V
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M
C
More on MVC
• The MVC separation allows you to plug in different
front-end clients
• Provides a separation in development, too
– Model is driven by data design
– Controller is driven by process design
– View is driven by screen design
M
V
• Different development skills for different styles of
presentation (application vs JSP)
• Swing attempted this but ended up with a separable
model architecture
– View and Controller layer are merged
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C
Agenda
• Introduction
• Example of using reusable components
• Design decisions and patterns
• Reference Framework
• Challenges
• Summary
• Q&A
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Reference Framework Architecture
Design Pattern Information Flow
View
Controller
View
XML, Result Sets,
Data Objects
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Model
Reference Framework Architecture
Technologies
View
HTML, JavaScript,
Java Server Pages,
Servlets
View
Controller
Enterprise Java Beans,
Messaging-Oriented
Middleware, Java
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Model
Relational Database,
XML Data Store
Reference Framework Architecture
Reusable Components
View
Display Elements,
XSL Transformation,
Custom Tag Libraries,
Common Web Servlet
Controller
View
Common Validation Rules,
ACL Modeled Security,
Session Handler,
Generic Page Processor
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Model
User/Group Profiling,
Event Notification,
Messaging,
Business Rules,
Application Security
Reference Framework Architecture
Additional Services
Services
Java Mail,
DB Connection Pooling,
Generic Workflow,
Audit and Logging,
Job Scheduling,
External Security
Integration,
Data Driven Lookups,
JMS Messaging,
XML Message Broker,
JNDI Lookups
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Reference Framework Architecture
Layers
Web Server
Technology
Application Server
HTML,
JavaScript,
JSP, Servlets
EJB,
Message-Oriented
Middleware, Java
Relational
Database,
XML Data Store
Display Elements,
Common Validation
Rules,
ACL Modeled Security,
Session Handler,
Generic Page Processor
User/Group
Profiling,
Event Notification,
Messaging,
Business Rules,
Application Security
Reusable
XSL Transformation,
Components Custom Tag Libraries,
Common Web Servlet
Services
Information
Flow
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Database Server
Java Mail, DB Connection Pooling, Generic Workflow, Audit and
Logging, Job Scheduling, External Secuity Integration, Data Driven
Lookups, JMS Messaging, XML Message Broker, JNDI Lookups
XML, Result Sets, Data Objects
TimeX MVC Usage
• Single servlet for Controller function
– Business logic is provided by support
classes (Handlers)
• Handlers use data objects (classes) to
interact with the database (Model)
– Usually static methods to call a SQL
statement or database procedure
• One handler per JSP
– This supplies the View
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Process Summary
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Process Summary
1.
Call servlet
2.
Gather request parameters, store session info
3.
Check privileges
4.
Get the proper handler
5.
Initialize the handler, validate if necessary
6.
Check the request action sent (LOAD,
FORWARD,SAVE_FORWARD, SAVE_LOOP
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7.
Get next handler if action is FORWARD or SAVE_FORWARD
8.
Dispatch request to the proper JSP
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Struts Components and Request
Lifecycle
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TimeX User Interface
• Login
• Select a time period
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Enter Time
• One day at a time
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Submit Time Report
• Employee is done with report
• Status changes to submitted
• Approver must review and approve
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Expense Report
• Follows similar flow up to the entry form
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Quovera Time and Expense Reporting
Requirements
• Secure web-deployed time and expense
(TimeX) reporting module
– Mission-critical for a consulting company
– Replace Excel solution
– Easy to use
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Quovera Time and Expense Reporting
Requirements
• Leverages reusable components
– Database design
– Back-end PL/SQL utilities (email, user
security, etc.)
– Java classes
• Fast
– Light-weight client
– High availability
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Design Decisions
• JSP solution
– Fulfills high-availability, fast, web-enabled
requirements
– Base the system on Quovera ATOMS and
Reference Framework
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Design Decisions
• Utilize Open source components
• Uses Model-View-Controller architecture
– Model-View-Controller (MVC)
• Model = data and values, validation, ranges
• View = display
• Controller = what happens when user
interacts with the component
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TimeX MVC Usage
• Single servlet for Controller function
– Business logic is provided by support classes
(Handlers)
• Handlers use data objects (classes) to
interact with the database (Model)
– Usually static methods to call a SQL statement or
database procedure
• One handler per JSP (View)
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Agenda
• Example of using reusable components
• Design decisions and patterns
• Reference Framework
• Challenges
• Summary
• Q&A
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Challenges in utilizing the
framework
• Client dictates technologies
• Components often have dependencies
• Some risk when compared to commercial
products
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Agenda
• Introduction
• Example of using reusable components
• Design decisions and patterns
• Reference Framework
• Challenges
• Summary
• Q&A
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Summary
• You are already using reusable
development components when you code in
Java !
• Design patterns are more reusable than
components
• Open source is useful and fun
• Blah, blah, blah …
End
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Agenda
• Introduction
• Example of using reusable components
• Design decisions and patterns
• Reference Framework
• Challenges
• Summary
• Q&A
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Thank You !
http://www.quovera.com/
Corporate Headquarters
275 Shoreline Drive, Suite 520
Redwood City, CA 94065
Phone: 650-232-6300
Fax:
650-232-6301
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Session # 2645