Visual Studio Tools for Office (VSTO)

I just wanted to call out the fact that VSTO will be an integral part of Visual Studio 2008 (was Orcas).

The packaging in the 2005 versions could have been clearer I reckon (and more cost effective!). I never fully understood which of the various components were required. Especially with the free SE thing. To be frank I gave the whole 2005 thing a bit of a body swerve (after reviewing it at RC2 stage way back when). 2008 however looks far more compelling. Especially now that Excel 2003 has significant market share.

I am assuming that the decision to package it in with VS2008 pro was somehow connected to poor sales of the standalone component (I heard the last VSTO user group meeting was held in a phone box at the bottom of XL-Dennis‘ street!). Its also likely that MS are keen to encourage the VS hardcore to consider Office apps rather than 3rd party controls. I’ll post more about my concerns with this later.

VS2008 beta2 is out now on a free download and reports I have read are that its very stable. It also includes a go-live license which means you can put the stuff you build with the beta into production. I wouldn’t personally be tripping over myself to do that with any important systems. But a distributed shopping list app might be ok. I got my copy on the cover of of my VSJ from those nice people over at Visual Systems Journal.

Visual Studio 2008 screen shot

For anyone who is not sure what VSTO is, its a set of starter projects like the old VB6 Standard exe, and Active-x dll ones. The difference being these projects also host an Excel session with a workbook. This allows simple seamless integration of code and spreadsheet, much like VBA. Except the code does not end up in the workbook, but sits as a .net component that is linked to the workbook.

VSTO is not the only way to combine .net and Excel, but it certainly seems to be the way things are moving. I’ll be looking at this in more detail as time goes on, as will Steve Hansen over at [Edit] And of course XL-Dennis has already written a ton of useful info over here.

VSTO will be one of the things we’ll be looking at during the Excel Developer conf on Sat 1 Dec in Cambridge. (Registration now open)



13 Responses to “Visual Studio Tools for Office (VSTO)”

  1. Dennis Wallentin Says:

    Well, if you come around the phone box at XL-Dennis street you’ll get all available info about VSTO 3.0. It’s rather crowdie so it may be difficult to get in, especially all nights when free beer is served. From what I’ve been told the phone box will expand and therefore XL-Dennis & staff are not able to visit the Data Island in the beginning of December.

    Meanwhile a good starting point is to visit where it appears to exist some VSTO stuff as well.

    Kind regards,

  2. Marcus Says:

    Touché. Excellent response Dennis.
    I’m sorry – where’s that free beer again?

    Regards – Marcus

  3. Simon Says:

    Sorry I missed you out Dennis (now fixed), I just happened to be chatting to Steve last week about some possible collaboration. Thats about the limit of my memory these days – 1 item in 1 item out!
    I’ll buy you (and Marcus) a beer if you get over for the conf.

  4. Dennis Wallentin Says:

    It’s served at the following place:

    No worries Simon, if you can make it to XL-Dennis street then you’re most welcome too. Give the beer at the conference to the person who can improve the Phone Box Pub concept.

    Kind regards,

  5. Simon Says:

    Absolutely perfect Dennis!!

  6. Ross Says:

    Interesting Simon, I installed 2008 a few days ago, again off the cover of VSJ. I was going to do a video of what it looked and felt like. I tired to build a hello world but I could not get menus to work properly – I’ll have to look into it. However, I was also thinking about asking what is the point of VSTO?
    Like you say, its not the only way, you ca write a DLL, or a managed com addin, which both have the huge advantage of being able to work with all of the Excel versions (post 2k) which I guess make up at 60-70% of the total population.
    The only thing I can see as a differentiator is the way isolation is handled. I know you can shim Com addins, but didn’t Stephen say something about it all being a bit dodge away! – I don’t know it’s all very confusing (not like Microsoft that is it!)

    BTW, While I was messing about, my project targeting 2003 told me I had to update the project as I had an explicit reference to 2003 and a implicit one to 2007 – or something like that anyway! – I think I also set it up to use .Net 2?

  7. Simon Says:

    I had that same upgrade problem, as if VS2008 is using VS2005 project structure. And it didn’t seem to like that I had Excel 2003 and 2007 on the same machine.
    I need to poke around into VSTO more to see what they are upto now. At least it now looks like it might be deployable.

  8. Dennis Wallentin Says:


    Due to the PIA MSFT recommend to only have one version of Excel installed. The days when we could have several versions on the same configurations are gone.

    I use Add-in Express .NET and their version neutral IAs allow me to have several versions installed (although it’s not officially supported).

    Please share Your experience when You have managed to create a workable CAS setting.

    Kind regards

  9. Ross Says:

    Si, Dennis,

    I just started another VSTO excel Addin Project closed and repoened and got the same thing, the error message is:

    Error 4 The project currently contains references to more than one version of office, a direct reference to version and an indirect reference (through ‘Microsoft.Office.Interop.Excel._Application.CommandBars’) to version Change the direct reference to use version (or higher) of office. C:\Documents and Settings\Ross\Desktop\ExcelAddIn1\ExcelAddIn1\ThisAddIn.vb 29 20 ExcelAddIn1

    I only have 2003 (i think), I think it’s been set up to add 2007 somewhere, the tool tip suggests i should use the casting method it has already used! – classic – just a beta bug I hope!

    anyway knocking it on the head for tonight!

  10. Dennis Wallentin Says:


    Which version of the PIA are actually installed in GAC? I would guess that it’s 12.0. If that is the case then remove them from the GAC, download the PIA 2003 and install them.

    Kind regards,

  11. Simon Says:

    “Please share Your experience when You have managed to create a workable CAS setting.”
    I think that might be:
    Please share Your experience if You manage to create a workable CAS setting.!

  12. Dennis Wallentin Says:

    Hehe – Indeed, that’s true Simon!

    A good start is to read the following article from MSFT:

    What I like to know is how many times do you need to read i through before you fully understand it. For me, I had to read it slowly 5 times before I managed to keep clear the mud.

    Kind regards,

  13. Methods In Excel » PED (Professional Excel Development) Second Edition!!!! Says:

    […] And finally, do you have any plans for a second international VSTO conference in the Phone Box, and will the beer still be […]

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