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Using and Extending Excel with Visual Studio

A high level discussion of the main options

Simon Murphysimon.murphy@codematic.netDeveloper – Codematic Ltdwww.codematic.net – Excel Development.

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Agenda• Background• Patterns and technical options• VSTO demo• The main questions (how to choose)• Automation v COM Add-ins• Demos

– Com Add-in– Automation Add-in

• Deployment• Justification• Summary & questions

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Background• On-line confusion• No (easy to find) succinct info from MS• Mild panic after VB6 retirement (VB6 ~ VBA)• Few books (changing rapidly)• Why target Excel?

– 400 Million installations– Very powerful, very programmable client

• ~ 200 objects• ~ 80 events• ~ 200 enumerations• ~ 4,500 methods and properties

• Note: this presentation pretty much ignores VBA

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Design Patterns

• Workbook with code behind• Excel Add-in

– COM Add-in– Automation Add-in

• Automation executable

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Working with Excel - The options

• VSTO (Visual Studio Tools for the Office System)

• COM Add-ins• Automation Add-ins• Standard automation projects

– Open, Automate, use features and Close Excel– Excel 97 maybe earlier?

• XLL Add-ins– Native win32 DLLs (ie pretty much C++) – Excel 4.0 maybe earlier?– Still very relevant

• VBA Add-ins – Not discussed here

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VSTO Demo

• VSTO (Visual Studio Tools for the Office System)– Special VS template projects that

incorporate strong office links.– Closest replacement for workbooks with

embedded VBA.– Excel 2003 professional or better– VSTO 2003 US only VSTO 2005 any

locale.– Locale still very much an issue for

other .net developments

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4 Big Questions

1. What version of Excel?2. Function or Feature?3. Application or Workbook Level?4. Who initiates connection?

• Or Hosted v None Hosted

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1. Which Version of Excel

• If Excel 2003 all options are possible

• Anything less than 2003 (professional)– VSTO (Visual Studio Tools for the

Office System) is not possible

• Anything less than Excel XP– Automation Add-ins not possible

• Anything less than Excel 2000– COM Add-ins not possible

• Total Office Installs – around 400M

Excel Versions ~

2003 – 15% - 60M

2002 – 35% - 140M

2000 – 40% - 160M

1997 – 10% - 40M

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2. Function or Feature?

• Function (as in worksheet function)– Automation add-in

• Visual Studio 6 (generally VB6.0)• Visual Studio .net• VSTO not appropriate

– XLL• Best performance

• Feature– COM Add-in– VSTO– Standard automation

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3. Application or Workbook Level?

• Application– COM Add-in– Automation Add-in– Standard automation project

• Workbook– VSTO– VBA

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4. Who Initiates connection?

• Excel (hosted)– VSTO– COM Add-in– Automation Add-in

• Your application (not hosted)– Standard automation project

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Demo

• COM Add-in – load up events– Application level functionality– Excel 2000 or better– Visual Studio 5 >>

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Automation v COM Add-in

• Automation Add-ins are COM add-ins that can be called directly from a worksheet cell.

• COM Add-ins – Must Implement IDTExtensibility2– Generally load on Excel start up (can be

changed)

• Automation Add-ins– May Implement IDTExtensibility2 (discouraged)– Loaded on demand only

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Demo

• Automation Add-in – Worksheet formula– Directly callable worksheet formulas– Excel XP (2002) or better– Visual Studio 5 >>

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Development & Deployment• Excel is written in unmanaged C with

COM interfaces for VBA and other apps.• VBA/XLL has the easiest initial

deployment (updates are more complex though)

• VSTO has the most flexible and overall easiest deployment (server or local)

• COM Add-ins & Automation Add-ins– standard COM local registry issues.– Should have a shim (Custom CLR loader)

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COM Shims• What are they?

– COM dll that loads Mscoree.dll which then loads our managed component

– Excel>>COMSHIM>>Mscoree>>MyAddin.dll

• Why use them?– Security (code signing)– AppDomain Isolation

• Protect other apps from failures in our component

• Protect our component from other failures

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Why bother?• Why change from the current VBA /

COM approach?– Deployment and maintenance easier

• 1 version• Write controlled location• Cleaner tiered architecture

– .net framework functionality– Visual studio .net IDE better than VBAIDE– Enterprise code reuse– .net security may be better than macro

security?

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When to bother?• Note: my personal guess only!• Mainstream in 2007!• Excel 12 due mid/late 2006

– Excel 12 is a genuine improvement

• VSTO 3 will probably match that time scale– Very likely to include more application level features

• Task panes, Add-ins, etc

• Approx 12 months to get reasonable uptake• VBA will be looking very shabby by then• VSTA (Visual Studio Tools for Applications) will

have fully arrived• .net framework should have reached saturation

level.

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Resources

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Summary

• VSTO for modern workbook based solutions• COM Add-ins for application level features• Automation Add-ins for worksheet functions

Solution Type

Technology Type

Workbook With Code

Behind

Application Level Feature

Custom Worksheet Function

Automation Project

VSTO COM Add-in Automation Add-in Win32 XLL VBA Standalone exe

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Finally

• Any questions?

• Simon Murphy• simon.murphy@codematic.net• www.codematic.net – Excel

Development.