Navigation Framework using CF

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Navigation Framework using CF

• Architecture for a Client-Server Application
  using the open standards of the Web

presented by
Kedar Desai
Differential Technologies, Fairfax, VA
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Navigation a new paradigm

• Non URL (menu based) navigation
• FORM based application control
• Queue and Keys philosophy

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What is Navigation?

• Users perspective
• Ability to use the system in the most effective
  manner.
• Designers perspective
• Ability to manage or direct the course of the
  user using the system.

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What is this Client-Server application?

• Two tier application
• Rich GUI
• Thick client built using tools like, PowerBuilder
  or Visual Basic
• MDI interface
• Interacts with a database at the backend
• Deployed using executables

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Associated problems

• Maintaining a code base
• DLL hell
• Distributing an exe
• Maintaining help files
• Difficulties in adding new functionality

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About the Application

• Justice Information System
• Psuedo three tier architecture
• Has a look and feel of a standard windows
  application

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Application architecture
Application Server
Database
ColdFusion 4.5
IE5.0, HTML, JS, CSS
Sybase database
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Challenges

• 200 database tables
• 500 functions
• Database driven
• Transaction intensive

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Application frameworks

• Two main frameworks
• Navigation
• Navigation
• Error handler
• Business Rules engine
• Security
• Each framework is an independent unit.

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What is so great?

• Uses ColdFusion.
• Enables parallel development of user interface
  and application logic.
• Gives a look and feel of a standard windows
  application.
• Extends ColdFusions error handler.
• Separates the GUI from the business logic.

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Features of the Framework

• Driven by keys.
• Works on a queue architecture.
• Maintains state in Session variables and allows
  multiple sessions from one client machine.

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Message Module

• Provides the ability to maintain messages in the
  database.
• Functions include
• Search for messages
• Add, Modify and Delete messages
• View specific details about messages

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Demo
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Function Architecture

• Five .cfm files per function
• Form page
• Main cfm
• OnError cfm
• CFForm cfm
• Presentation cfm
• Action page
• Action cfm

• Hidden fields
• Function Id
• Page Id
• Target Function Id
• Main cfm file name
• OnError cfm file name
• Action cfm file name

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Navigation Controllers

• Form controller
• Opens the page
• Action controller
• Fires the action

• Error controller
• Handles errors
• Business Rules Engine
• Handles business rule validations
• Keys/Queue controller
• Maintains the keys and queues

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What are keys?

• Every function has a set of input and output keys
• A key is a value that fetches data to be
  displayed on the page
• If no keys exists, the default function is opened.

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What is a queue?

• Maintain information about the activities that
  the user wants to perform.
• Works on FIFO logic.
• Two types
• Function queues
• store the function ids in a queue.
• Data queues
• store the keys in a queue.

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Page loading process
FORM Controller
Main cfm file
Error propagation is 5-4-3-2-1-0
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Action processing logic
Action Controller
Error propagation is 2-1-0 or 3-0
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Features

• Secure access
• Centralized action and form pages
• Centralized error handler
• Everything is a custom tag
• Complete isolation of logic presentation
• Supports version control and independent
  development
• F5 (refresh) works as in a browser

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Points to ponder

• Browser back and forward buttons a problem
• Custom tag directory cannot be used
• Not much use for Application.cfm

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Productivity metrics

• Built in under three months
• A team of five and churning out a function every
  two days.

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Thank You
Visit us on line at www.differentialtech.com
or write to me at desaik_at_differentialtech.com
desaikedar_at_hotmail.com