Corey Roth [MVP]

That’s a mouth full.  I always suspected it was possible to use Visual Studio 2010 to package up my SharePoint web parts and other artifacts into a solution (.wsp file) and turn around and deploy that code into MOSS 2007.  Today I gave it a try and it actually works pretty well.  This post will show you how to do it.  I will remind you that you won’t be able to take advantage of any of the automatic deployment, debugging features built into Visual Studio 2010 and SharePoint 2010, but you will have a nice solution file that was built automatically without having to use a third party tool like WSPBuilder.  You can then take the solution package and deploy it to SharePoint with stsadm.

I will start off by using the SharePoint 2010 Empty Project Template.  Now, unfortunately, the wizard that starts this project has a dependency on SharePoint 2010.  It simply won’t run without it.  However, if you happen to already have a copy of a project that has been created, you can open an existing SharePoint 2010 project template on a computer that does not have SharePoint installed.  I have attached a copy of my Visual Studio solution for you to use as a starting point if you need it. 

Once I have my project open, I proceed to create a web part as shown below in the Solution Explorer.

I don’t have to make any modifications to the class.  So I add some simple “Hello, World!” code to it.

We’re targeting SharePoint version 3, so that means we need to change some references.  All of the DLLs in SharePoint 2010 are version 14.  We need version 12 DLLs.  So what you will need to do is go get a copy of Microsoft.SharePoint.dll (and possibly Microsoft.SharePoint.Security.dll) from your version 3 SharePoint farm.  We then need to remove the reference to the version 14 DLLs.  Click on Microsoft.SharePoint.dll and Microsoft.SharePoint.Security.dll and remove them from the solution.  We then add our version 12 DLLs to the references list and we’re ready to compile our web part for WSS3. 

At this point, I will remind you of the caveats of perusing this completely unsupported approach.  Obviously, you can’t need to make sure you are only using API calls from version 3.  Using a class from SharePoint 2010 is obviously not going to work.

Build your project and it should compile successfully.  Now, I figured everything would work at this point but I discovered one thing that I had to change in this process.  The SharePoint 2010 solution schema has a new attribute called SharePoint version on the SharePoint element.  WSS3 does not like this.

Luckily, I discovered, that if we delete the value from the property window, it actually removes the attribute.

Simply, remove the value there and we are ready to package the project.

When this is complete, you can browse the file system and find your .wsp file in the bin folder.  Copy the .wsp file to the SharePoint 2007 server if you aren’t already on it.  Then add and deploy the package with stsadm.  At this point, you will have a feature that you can activate on your SharePoint 2007 server.  Go to site collection features and activate it.

The web part should now be in the Solution Gallery.  Now edit a page, and add a new web part.  Your web part should be in the group labeled Custom assuming you haven’t changed it.

We can now verify that the web part code works on the page.

As you can see it’s really pretty easy to build a WSS3 web part in Visual Studio 2010 and deploy it.  We lose some of the cool VS2010/SP2010 integration features of course, but the fact it builds the package for us is a huge win.  Not to mention, upgrading our code to work in SharePoint 2010 later will be pretty easy since all we have to do is change our references from the version 12 to the version 14 DLLs.  I’ve only covered how to do a web part here today.  I suspect other SharePoint Project Items will work as well.  I’ll try them out soon and let you know how they work.  As a reminder, I have attached a copy of my solution to this post for you to use in case you don’t have SharePoint 2010 installed any where.  Give it a try and let me know if it works for you.