• Chart: VSTO vs. Other Visual Studio Editions

A prerelease version of Visual Studio 2005 Tools for Office (VSTO) enables developers to use the .NET Framework and .NET languages to build smart client solutions that connect back-end systems, such as customer relationship management (CRM) applications, to Outlook information, such as e-mail, contacts, and calendars. However, Outlook extensions are more complex to build and develop than Word or Excel solutions, and overlap among competing Microsoft smart client technologies may confuse IT planners.

Connects E-Mail with Business Applications

VSTO is an edition of Visual Studio that enables developers to use the .NET Framework and languages such as C# and VB.NET to build extensions to Word, Excel, InfoPath, and now Outlook. These extensions support Microsoft's vision of "smart client" applications built on top of Office that take advantage of local processing power and storage but that communicate with server-based back ends to exchange and manipulate data, typically using XML as the data interchange format. For example, a smart client Outlook application might allow a sales person to take an e-mail from a customer and look up the customer's data in a CRM application without having to use a separate CRM client application, thereby allowing the sales person to respond more quickly and accurately.

Prior to the latest beta of VSTO 2005, a developer building such an application would have had to use Outlook's COM-based add-in APIs, which didn't support the .NET Framework and were thus more difficult to create. With the new release of VSTO 2005, developers can quickly create an Outlook add-in and debug the add-in from within Visual Studio. For instance, developers can program add-ins to do the following tasks:

• Create custom menus based on the Outlook folder the user is viewing
• Create custom toolbars
• Create and display forms using the Windows Forms APIs built into the .NET Framework
• Access the contents of the user's calendar, mail, and tasks.

Deployment, Overlap Cloud Picture

Deployment of Outlook solutions is complicated by several factors. Outlook is different from Word and Excel in that it isn't a document-based application. VSTO solutions built on Word and Excel can be distributed as .DOC or .XLS files that are linked to the appropriate .NET code and can be opened directly by the user. Outlook solutions, on the other hand, must be deployed as a series of DLLs and registered in the Windows Registry before they can be used. In addition, some known bugs in the way Outlook interacts with add-ins require significant code changes that Microsoft has thus far been unwilling to fix.

In addition to deployment concerns, overlap with other Microsoft products and technologies make choosing a smart client technology harder than it should be. Specifically, the Information Bridge Framework (IBF) also provides an API for using the .NET Framework to build Outlook solutions that access Web services. IBF, however, is a more specialized solution than VSTO: IBF solutions can access only a subset of Outlook's capabilities and require that the user be connected to the network, while VSTO solutions have access to a wider range of user interface options and can be designed to work online or offline.

Finally, VSTO is shipped as a discrete subset of the high-end Visual Studio Team System, and doesn't support the full set of languages. As a result, developers without the Team System may need to purchase both Visual Studio 2005 Professional and VSTO to develop a broad range of solutions on Microsoft's platform. (For a comparison of various Visual Studio 2005 editions, see the chart "VSTO vs. Other Visual Studio Editions".)

Availability and Resources

A production version of the Outlook functionality will ship with VSTO edition of Visual Studio 2005, planned for Nov. 2005.

The beta for VSTO 2005 is available for download at www.microsoft.com/downloads/details.aspx?FamilyId=74B56C72-7A1F-431F-A29C-58EB39E97A86&displaylang=en.

Technical details on Outlook support are in a white paper at msdn.microsoft.com/library/en-us/odc_vsto2005_ta/html/Office_VSTOOutlookAdd-inArchitecture.asp.

The Information Bridge Framework is described in "New Platform for Office Smart Clients" on page 24 of the July 2004 Update and "Office Bridge Platform Updated" on page 22 of the Apr. 2005 Update.

Smart client technologies are compared in the chart "Platforms for Office-Based Clients" on page 25 of the July 2005 Update.

Microsoft's recommendations for Office smart client application technologies are at msdn.microsoft.com/smartclient/understanding/default.aspx?pull=/library/en-us/odc_ip2003_ta/html/odc_ipoffice2003smartclient.asp.