What is MVC? At the very least it’s just another computer acronym…Model-View-Controller It might be new to you but it’s been around for 30 years In varying degrees it is probably something you are already doing but didn’t know it But before we explain MVC any further…

Audience Poll Who here already has been or will plan to integrate an OpenInsight application with an alternative visual interface and/or with an alternative database server? If you answered “yes” to this question then MVC should be of interest to you…

“The Shape of Things to Come” 2010 Revelation Software Users’ Conference – 22 total presentations – 10 related to non-traditional visual interfaces or databases servers (at least for Revelation based apps) – 40% of these presentations are telling us that the future requires us to think differently

“The Shape of Things to Come”

Model-View-Controller Architectural pattern for designing software where an application is described in and designed in three separate layers: – Model = Relates to the application’s database and business logic – View = Relates to the application’s presentation of the data – Controller = Relates to the application’s flow and ties the other layers together Generally assumes that application layers are loosely connected – A Bit of History

Model-View-Controller Coined in the late 70’s and made popular in the early 80’s with Smalltalk Developed with Object Oriented technology in mind Early versions assumed dumb clients Spin-off versions include Model-View-Presenter, Model-View-Template, and Model-View-ViewModel – A Bit of History

Who Needs to Know MVC? Anyone who needs to substitute or allow for alternative layers with minimal code rewrite – Presentation layer - WPF, Flex, HTML, iPhone, webOS – Data layer - SQL, U2, AmazonS3, Google App Engine (e.g. Cloud resources – Tom Wilson) – Leverage existing resources – Tom Wilson Anyone who wants easier code management and documentation Anyone who develops with teams who are focused on a specific layer of the application

Who Needs to Know MVC? Anyone who wants better unit testing of their code Anyone who wants more reusability of their code Anyone who wants more scalability in their application Ask a Java, PHP, Ruby,.NET, or Cocoa developer

Who Doesn’t Need to Know MVC? Anyone who prefers a ‘git-r-done’ approach Anyone who never intends to work outside of OpenInsight

Model-View-Controller – A Closer Look Disclaimers – I am not an MVC purist or expert – Much of what I am presenting is a “work-in- progress” effort – While MVC philosophy is always the same, pundits will differ on how to apply it

“The Shape of Things to Come” The Challenge – Move from “direct connection / local data” to “indirect connection / global data” – Preserve the valuable repository of business logic – Allow for easy introduction of new components such as new visual interfaces or new database technologies – Avoid rewriting code

Separation of Concerns (Layers) –M–Model –V–View –C–Controller Model Model View Receivers User Inputs Calls Appropriate Resources Receivers User Inputs Calls Appropriate Resources Controller Model-View-Controller – A Closer Look Handles Data Handles Business Logic Handles Data Handles Business Logic Presents Data to User Handles Event Processing Presents Data to User Handles Event Processing API Events Requests Notifications API Events Requests Notifications API Results Responses Notifications API Results Responses Notifications

Model-View-Controller vs. n-Tier Architecture Logic Tier Presentation Tier Data Tier n-Tier View Controller Model MVC Business Logic Physical Data

Amazon’s Shopping Cart

AREV

OpenInsight

Flex - Form Design Courtesy of Clay Borne

Calculate Shipping - Flowchart Start End Have Zipcode? Have Zipcode? Set “Missing Zipcode” Error Set “Missing Zipcode” Error Shipping Logic Return Shipping Costs NoYes Display Shipping Cost (Color Red if too much) Display Error

MVC Examples – Side by Side Comparison View Controller Model Basic MVC OI Form Basic+ (Commuter) OI Form Basic+ (Commuter) In Process Engine Basic + In Process Engine Basic + Linear Hash Basic+ (MFS) Linear Hash Basic+ (MFS) Pure OI HTML Javascript HTML Javascript OECGI/2 Basic+ OECGI/2 Basic+ Linear Hash Basic+ (MFS) Linear Hash Basic+ (MFS) HTML / OI Flex/Flash ActionScript Flex/Flash ActionScript OECGI/2 Basic+ OECGI/2 Basic+ Linear Hash Basic+ (MFS) Linear Hash Basic+ (MFS) Flex / OI OI Form Basic+ (Commuter) OI Form Basic+ (Commuter) In Process Engine Basic + In Process Engine Basic + SQL Basic+ or Direct SQL Basic+ or Direct OI/ SQL

Final Thoughts Don’t swallow the elephant – Take one bite at a time – Translation: Don’t force yourself to convert everything to MVC. Ease into it Don’t force a square peg in a round hole Build a framework and standards to make this easier