strategic guidance

Strategic Guidance for AVR Classic legacy

applications

Presented by:Roger Pence

Education Director, ASNA

2Copyright © 2012 by ASNA.

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A critical legacy dependency

• Many customers have developed substantial Windows applications with AVR Classic

• These applications…– Have enterprise dependence– Have been very custom-tailored to solving

unique business problems– Are widely deployed and used– Are usually several years old

• Most of these customers have one simple question…


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Now what?


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There isn’t a magic answer!

• Alas, there isn’t a magic answer to the question

• The answer depends on what your needs and motives are for the application

• So, yes, there isn’t a magic answer, but there are answers!


4:20

COM has served us long and well

• COM is old and getting older!– COM was introduced in 1993—it is 18 years old– AVR 1.0 was released in 1994—it is 17 years

old

• Migrating code from COM to .NET is very troublesome (more on this later)– MS offers no tools for migrating VB COM to

VB.NET

• COM has served us long and well, but its role in modern application development is rapidly diminishing

Copyright © 2012 by ASNA. 6

COM will be with us for a long time, but make no

mistake, the sun is clearly setting on COM


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COM is the programming equivalent of Mick Jagger…

• Both have been with us for a long time

• Both are old friends

• Both have worked very hard for us

• Both are really starting to show their age

• Clearly, both have reached the end of their prime!


COM then COM now


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This session’s mission

• What you should or shouldn’t do is very dependent on lots of issues

• We can’t give you the answer

• What we can do is share some potential answers

• You don’t have to do anything we suggest

• But…


You have to do something!


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A rational plan now…

• Protects you from needing to make hasty decisions

• Keeps you from reacting to events beyond your control

• Lets you act with a well-crafted strategy to prepare for the future

• You need a rational plan…now!


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ASNA’s 5 R strategy for future-proofing AVR Classic

apps1.Relax

2.Refine

3.Restrain

4.Reinvest

5.Reimagine


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Relax

• We do know that COM is in the winter of its life, but…– COM isn’t going away anytime soon

• MS has a good long-term strategy in place for your COM investment protection

• After all, MS has the same problem you do…– Legacy COM code. Lots of it.

Relax > Refine > Restrain > Reinvest > Reimagine


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Don’t overreact

• We feel it’s very important that you craft a good long-term strategy for your AVR Classic apps

• But you don’t need to do it before 8pm this evening!

• The COM click is ticking but it’s nowhere near its final count down

• You have time to think through your decisions before you make them



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Leaving XP behind? Win7 has your back

• MS had big problems with COM interoperability with Vista—but has learned from those mistakes– MS built a great COM-escape hatch into

Windows 7– Each copy of Windows 7 offers a free XP virtual

machine

• Each copy of Win 7 includes an XP license for the Win 7 XP VM mode

• You can launch the entire XP VM or launch XP VM-specific shortcuts from the Win 7 host



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Windows 7 Windows XP mode with Virtual PC in

action• Show Windows XP mode in action

• Getting Windows XP mode for Win 7– Download what you need here:

• You’ll need both Windows XP Mode and Windows Virtual PC

http://www.microsoft.com/windows/virtual-pc/



http://www.microsoft.com/windows/virtual-pc/


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Windows XP Mode

• To surface XP shortcuts to your Win 7 host:– Create a folder named “Programs on the XP

VM” user c:\Documents and Settings\All Users\Start Menu

• Then create shorts to your EXEs and other files with the Shortcut wizard – Dragged and dropped shortcuts won’t work! – These shortcuts are then automatically

surfaced in your Win 7 host’s Start Menu– Installed programs automatically surface in the

Win 7 host’s Start Menu



Windows XP Shortcut wizard is available from the Windows Explorer context menu.


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Refine

• Get your AVR Classic applications to code complete status as quickly as possible– The goal is to be able to say, “This version is

done, with no new features planned or to be available for it.“

– Fixes may be added, but no new code!


Code complete: A release is called code complete when the development team agrees that no entirely new source code will be added to this release.


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Minimize third-party dependencies

• Third-party components represent a weak spot in your exposure of what might continue to work in the future– Mabry and Graph Control are gone – Minimize your use of third-party controls– Minimize your use of programming with the MS

Office COM objects—Office version dependencies are a huge source of moving code forward!



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Understand COM <-> .NET interoperability

• COM and .NET do coexist nicely – AVR Classic apps can consume .NET DLLs quite

easily– .NET apps can consume AVR Classic DLLs with

just a little effort– This might help you leverage .NET work as you

make your Classic apps code complete

• Current .NET DG versions also support Classic

• Tim Jannsen’s .NET and AVR Classic Interoperability session covers this in detail



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Restrain

• When you have your AVR Classic apps code complete, restrain yourself from changing them or adding new features to them!

• You have to draw a line in the sand between the old and new! – That must be a part of your strategy!

• Also, restrain yourself from writing anything new with AVR Classic!



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Reinvest

• As you chart your corporate and personal course for life after COM, consider the training and skills you and your team need to acquire

• Chart a specific course to learn:– .NET in general– Web development (both server-side and client-

side)– SOA architecture– Windows forms alternatives (more on this in a

moment)– Database design



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Learn about good application architectures

and patterns• Many of the apps built with AVR Classic

owe more to serendipity than to engineering and architecture

• The application lifecycle was – Code a little – Deploy a little– Goto TOP

• Today’s applications require more discipline and design—and the application of solid programming fundamentals



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Invest in your team’s skills• Recommended books– Robert Martin – Clean Code– Steve McConnell – Code Complete (2nd Edition)– Douglas Crockford – JavaScript: The Good Parts– Elisabeth Freeman – Head First Design Patterns– Martin Fowler – Refactoring: Improving the

Design of Existing Code– Cwalina and Abrams – Framework Design

Guidelines



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Invest in your team’s tools

• Source control– Subversion, Git, SourceGear Vault

• Automated build process– MS Build, PowerShell, Cruise Control, Team City

• Formal bug logging– Bugzilla, BugTracker.NET, Fogbugz

• Unit testing– nUnit, xUnit



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Don’t make this mistake!

• Don’t consider the need to migrate or rewrite your AVR Classic app in .NET an opportunity to learn .NET

• It’s vital that you learn .NET first! – As you move your COM app to .NET you’ll need

to make many informed decisions on the .NET platform

– You can’t make good decisions until you know and understand .NET



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Reimagine

• We built AVR Classic apps with several, nearly universal, practices:– Monolithic – no separation of concerns between

UI, logic, and IO– Global variables all over the place– Very busy event handlers– Little or no modularity– Applications were very stateful

• All of which are the polar opposite of what any modern software construction book recommends!



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Reimagine• You have an opportunity now to either:– Create a long-term software asset or…– Write another legacy application heavily

dependent on a specific UI

• Which would you rather do?

• Before you rewrite, migrate, or build around your existing applications, stop and think a bit about their longer-term purpose



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Pocket computers are changing everything

• Everyone in the room today has a computer in their pocket or purse! Maybe two.

• The redistribution of computer availability is changing everything

• Make no mistake: mobile enterprise doesn’t loom on the horizon– It’s here – It’s doable– It’s important– And your competition is doing it



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What UI should you target?• You shouldn’t target any UI!

• Build non-UI dependent services so that separate UI layers are possible

• Who knows what UI you’ll be asked for next?– Win forms?– Web forms?– HTML/HTML5 for mobile?– Silverlight for a Win phone?– Native mobile for Android or iPhone or iPad?– WPF? – Windows 8 Metro?



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Architecture of most AVR Classic apps today

• There is little, if any, separation between the UI, DB, and business logic layers

• All three layers are heavily embedded with each other

• Virtually impossible to factor out the UI



Beware: legacy code.

This software has

limited future value!


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Creating an application with discrete layers


• Writing your apps in discrete layers makes it more flexible

• Here there is a very clear separation of concerns between the layers


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Adding support for Web forms


• With business logic and DB access as discrete layers, it’s possible to write a separate layer UI for Web forms


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HTML/HTML5


• Using HTML5 is a good, general purpose strategy for mobile development

• Apps run in mobile device’s browser

• CSS media queries help structure UI layout


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Silverlight on the Win phone


• Silverlight and WPF may or may not make it generally

• But it’s looking like Silverlight will at least persist as the Win phone UI for the enterprise


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Maybe even native mobile


• Writing native mobile apps is a pretty hefty gamble

• But if you need it, a layered software approach makes it possible


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A layered architecture makes it possible to say

“Yes”


• Without a good layered architecture, you simple don’t have a “yes” option in your programming kit bag


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Who knows what’s next? Be prepared!


• A layered architecture turns what would have otherwise been a legacy asset into a long-term software asset


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The AVR Upgrade Assistant

• If you are on maintenance, and own AVR 4.1 and AVR for .NET, there is an Upgrade Assistant (UA) available in AVR 4.1

• The operative word here is “Assistant”!

• The UA isn’t an application migration facility, but, for the right apps, it can help lay the groundwork for converting an AVR Classic app to .NET



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The UA requires intermediate .NET

knowledge• Don’t assume that you can use the UA to

learn .NET—you can’t!

• You must be well-versed in both AVR for .NET and AVR Classic to get good UA results

• The UA only gets you started, you must make lots of decisions as you remediate the app—those decisions require .NET knowledge



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UA issues• Third-party controls are troublesome– Beware: many COM controls companies are

now gone!

• MS Office dependencies

• OSFile and MiscCtrls dependencies

• The UA doesn’t map things to .NET that required controls or DLLs in AVR Classic– Date and time conversions– String operations– Edit words and edit codes



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UA issues• Subfiles are troublesome to migrate well– And subfiles are at the heart of many

applications– We’ve tried twice to automate subfile

migration– The “subfile” model is so fundamentally

different in .NET

• DB connections aren’t localized in .NET– Special care must be taken to keep from

launching many OS/400 jobs with migrated code (or even slopping .NET from-scratch code)

• Win forms are the only target—no browser UI target



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The UA might work for you

• The UA is good for very small, well-focused applications

• But for larger applications we’re not sure it’s the best long-term answer to the question

• The UA imposes a fixed model that might be troublesome to grow out of

• We know that it is very hard to automate COM to .NET migrations– MS long ago gave up doing so with VB6

to .NET



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General advice summary

• COM isn’t going away anytime soon– Use Win 7 XP mode when necessary

• Finish your COM apps and then freeze them– Develop the discipline to not write any new

AVR Classic apps

• Start now building .NET services that replace or augment your AVR Classic apps– Give very serious thought to persisting the Win

forms model– Learning .NET is high on your to-do list


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General advice summary

• Start building tangential apps using those services to augment your AVR Classic apps– These are front-end apps—your services should

do the heavy lifting– Maybe start with a browser-based UI

• Don’t over-expect what the UA can do– It’s usefulness is rather narrow and specific– Understand its model – Learn .NET before you use the UA– Identify things AVR Classic is doing that .NET

does very differently

strategic guidance

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