Microsoft & .NETUsing Visual Studio to Write Word Add-ins

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For a long time, businesses have relied on Microsoft’s
Office applications to help running their daily routines.
Word is used to write e-mails and letters, Excel does the
calculations, and Outlook communicates. Everyone has seen a
slideshow made with PowerPoint. During the years, Office has
grown, and today the number of applications part of the
suite has grown to over ten.

Although many businesses can run their business with
stock versions of these products, it is common to repeat the
same steps again and again. For instance, sales people might
copy and paste information from their sales system to a Word
document, write their offer, send it out, and then return to
the sales system to mark their offer as done. And then they
start all over again.

As with many other Microsoft products, Office
applications are also highly customizable. In the past few
releases, extending these applications has become easier,
and you as a developer are not anymore limited to writing
COM DLLs with complex interfaces. Today, .NET
developers can also easily get started.

In this article, you are going to learn how you can use
Visual Studio 2008 and .NET to write custom add-ins for
Word. Along the way, you will explore the possibilities for
writing such applications. For instance, you can integrate
databases, web services and even blogs to your add-ins.

Say hello to VSTO

Developing applications for the Office products, and
especially for Office 2003 and 2007, is best done using
Visual Studio Tools for Office, or VSTO. With VSTO in Visual
Studio 2008, you can create different types of applications
that utilize the Office products as a platform. For
instance, you can create application-level add-ins,
document-level customizations, templates, workflows, and so
on. And as you might guess, you can develop your
applications from the convenience of the Visual Studio

Love or hate it, the Office 2007 release bought
developers the Ribbon (Figure 1). With VSTO, you can also
create your own customizations to the ribbon, for example by
adding buttons or creating new groups of commands. Although
ribbon customizations are not the focus of this article, it
is important to realize that this kind of user interface is
getting more and more common. Windows 7 also contains a
ribbon interface in many of the built-in applications such
as Paint and Wordpad.

Click here for larger image

Figure 1. Office 2007 bought us a new user interface along with the Ribbon.

Office applications have had a user interface element
called a task panel for a long time already (Figure 2). With
VSTO, you can create your custom task panels, and for the
purpose of this article, they are a great way to expose the
add-in’s user interface, but more on that shortly.

Click here for larger image

Figure 2. The Mail Merge feature uses a custom task panel to
display its interface.

If you have studied Office application development
before, you might have the impression that such development
work is hard. With previous versions of Visual Studio, this
arguably was the case, as you had to fiddle with different
COM interfaces, primary interoperability assemblies (PIAs),
and so on. But if you are using Visual Studio 2008 and are
targeting Office 2007 applications, things have gotten much

Installing VSTO usually happens along with Visual Studio.
When selecting the features to be installed, you will also
have the chance to select VSTO components (Figure 3). Note
however, that VSTO is only available from Visual Studio
Professional upwards. It is not available in the Visual
Studio Standard or Expression editions, nor can it be
purchased separately.

Click here for larger image

Figure 3 – Visual Studio Setup Screen.png

Figure 3. VSTO components are part of Visual Studio 2008
Professional and Team editions.

Creating a custom solution for Word

A technology like VSTO is best demonstrated with the help
of a sample application. To demonstrate the possibilities of
expanding Office applications with a custom solution, this
article walks you through in creating an add-in for Word
with VSTO in Visual Studio 2008.

The add-in itself contains a custom task panel. The
purpose of this panel is to let a sales person send quotes
to customers more efficiently. The sales person can simply
enter a customer ID, and automatically fetch customer’s
basic information into the active Word document. The panel
also contains a little utility to convert U.S. dollar amount
to euros using a web service. Finally, once the document is
saved, the add-in posts an update to a public blog. This
way, other sales persons are aware of the updated quote.

To begin developing your custom task panel, you first
need to fire up Visual Studio 2008. Choose to create a new
project (with the File/New/Project menu command), and in the
subsequent New Project dialog box, navigate to the
Office/2007 project type node on the left (Figure 4). From
there, select a Word Add-in, enter a name for your project
(such as WordSalesToolsAddIn), and click OK.

Click here for larger image

Figure 4. Starting a Word add-in project is easy with the
Office project templates.

Once Visual Studio has finished creating your project
from the template, you should see a project with several
files and references (Figure 5). For instance, under the
Word folder, you should see a file named ThisAddIn.cs. This
file acts like the Global.asax.cs file in ASP.NET web
applications: the code in the file is executed when the add-
in first loads, and also when add-in is unloaded, i.e. when
Word closes down.

Click here for larger image

Figure 5. An empty add-in project as created by Visual Studio.

If you run the project immediately after creating it,
Visual Studio will automatically register your add-in so
that Word can load it, and will then start Word. This makes
development and testing very easy. However, unless you have
written additional code to the project, you cannot actually
see anything in Word when you run your project. Even on the
Ribbon, the Add-ins tab (if visible) doesn’t contain any
hints about your creation.

Of course, creating a custom task panel will create
something that’s visible in Word. At this point, you might
be tempted to return to Visual Studio, open the Add New Item
dialog box (Project/Add New Item) and look for a custom task
panel object. Unfortunately, such an object does not exist.
Instead, to create custom task panels for Word and other
compatible Office applications, you need user controls.

Task panels as user controls

To create a new custom task panel for Word, you need to
add a Windows Forms user control to your project. To do
this, open the Add New Item dialog box and select the User
Control template from the Windows Forms group (Figure 6).
Alternatively, you can use the Project menu’s “Add User
Control” command.

Click here for larger image

Figure 6. Custom task panels are implemented as WinForms
user controls.

Once added, the user control will show as a
blank, gray area in the Visual Studio designer. The next
step would be to add controls to the designer surface. You
will also need a small piece of code in the ThisAddIn.cs
file to register your task panel with Word, and make it
visible. The code is similar to the following:

SalesToolsUserControl userControl =
new SalesToolsUserControl();
CustomTaskPane myCustomTaskPane =
userControl, “Sales Tools”);
myCustomTaskPane.Visible = true;

This code is added to the ThisAddIn_Startup method in the
ThisAddIn.cs file. In the code, an instance of the user
control (here called SalesToolsUserControl) is created, and
then it is added to the list of custom task panes that Word
controls. Finally, the pane is shown on the screen.

Implementing the functionality for the add-in

Once you have the basic user control skeleton created for
your custom task pane, it is time to add some functionality.
You can easily design the user interface of your pane in
Visual Studio, as a full-blown form designer is already
there. By default, Word sets the pane’s width to equal 200
pixels, with a height dependent on the size of Word’s main
window. You might wish to set the width of your user control
to equal 200 pixels so that designing would be easier.

Figure 7 shows the designed user interface for the sample
user control. Overall, the user interface itself is very
basic, but it’s the underlying code that makes the add-in
useful. The first feature in the add-in allows the user to
type in a customer ID, and then the add-in will fetch that
customer’s details from the Northwind SQL Server sample
database, and add them to the active Word document.

Figure 7. The sample application’s task panel in Visual Studio designer.
The code to fetch the details is straightforward: an SQL
connection is opened, a command is executed, and finally a
SqlDataReader object is used to fetch the results of the
query: string connStr = Properties.Settings.

SqlConnection conn = new SqlConnection(
string sql = “SELECT [companyname], “+
“[contactname], [address], [city], ” +
“[region], [postalcode] “+
“FROM [customers] ” +
“WHERE [customerid] = @custid”;
SqlCommand cmd = new SqlCommand(
sql, conn);
“@custid”, customerId);
SqlDataReader reader =
if (reader.Read())
CustomerDetails cust =
new CustomerDetails();
cust.CompanyName = reader.GetString(0);
cust.ContactName = reader.GetString(1);
cust.Address = reader.GetString(2);
cust.City = reader.GetString(3);
if (!reader.IsDBNull(4))
cust.Region = reader.GetString(4);
cust.ZipCode = reader.GetString(5);

// finished
return cust;

Here, the connection string is read from the add-in’s XML
configuration file, and the given customer ID is passed as a
parameter to the SqlCommand object. The results are returned
in a custom class instance, which contains simple public
properties for each value.

Once the query has been executed, it is time to insert
the results into the active Word document.

This is done
with the following code:

CustomerDetails cust =
// format text
StringBuilder buffer = new StringBuilder();
// insert text at the current cursor location
word = Globals.ThisAddIn.Application;
Word.Range selection = word.Selection.Range;
selection.Text = buffer.ToString();

The main interaction with Word happens in the last three
lines of code. The Globals class is a designer-created class
that is part of every Word add-in project, and is created
automatically by Visual Studio when you start the project.
It lives in the hidden ThisAddIn.Designer.cs file. Through
the Globals object, you can access your add-in’s ThisAddIn
class. In turn, this class then contains the Application
reference, which points to Word’s automation interface
master object. The Word object is defined in the
Microsoft.Office.Interop.Word.Application namespace, which
has a rather lengthy name to type. Thus, you might wish to
use the following C# using statements to help you manage the
long names:

using Word = Microsoft.Office.Interop.Word;
using Office = Microsoft.Office.Core;
using Microsoft.Office.Tools.Word;
using Microsoft.Office.Tools.Word.Extensions;
using Microsoft.Office.Tools;

These same using statements are available in
ThisAddIn.cs, from which you might wish to copy them to your
user control file.

Converting currency values

The next part of functionality in the sample add-in is
the ability to convert currencies. In this case, the sample
application can take a USD dollar amount, and convert it to
Euros (€). This is done with the help of a free currency
conversion service available at

To use this service, you will first need to add a service
reference to the project. This is done easily using the Add
Service Reference dialog box in Visual Studio, launched for
example using the similarly named command in the Project
menu. Once the reference has been added, the following code
can be used to convert a USD amount into Euros:

float usdAmount = float.Parse(usdAmountTextBox.Text);
client = new CurrencyRateService.CurrencyRateServiceClient();
float euroAmount = client.GetEuroAmount(
“USD”, usdAmount);
MessageBox.Show(“$” + usdAmount + ” is ” +
euroAmount + ” €.”);

First, the code takes the USD amount the user has
entered, and converts the string to a float value. Then, an
instance of the web service client class is constructed
(Visual Studio automatically creates the
CurrencyRateServiceClient class when the service reference
is added). The next step is to make the actual web service
(SOAP) call using the GetEuroAmount method of the service.
This method takes in a currency amount in any supported
currency, and a string specifying which currency the value
is in. The return value is the amount in Euros with the
current exchange rate.

Publishing to a blog

In a corporate setting, sharing information is a
necessity. For instance, if a member of a sales team creates
or updates an important offer, the other members of the team
should know about it. However, letting other people know
that you’ve updated a document is an additional, often
manual step. Why couldn’t the system automatically send a
status update to colleagues whenever an important document

In the sample application, this need to inform others is
addressed via a blog. Whenever the user saves the offer
(i.e. commits the updates made), the add-in automatically
publishes a new entry on a Google Blogger blog, which is
available at (Figure 8). The Blogger
service uses a free HTTP based API, which is divided into
two major parts: authentication with the generic Google
authentication APIs, and the specific Blogger interfaces to
submit blog posts.

Click here for larger image

Figure 8. The sample application can publish to a Google
Blogger blog.

Since the focus of this article is in Word add-ins and
not the Google interfaces, only a short description follows.
As mentioned previously, the first part of using the Blogger
service is to authenticate properly. This is done by sending
a HTTP POST request to the authentication URL, and passing
in the username and password for the service. In exchange,
the service returns an authentication token, which must be
passed when submitting a post to the user’s blog with the
Blogger API.

The following is a snippet of the code to authenticate
with the service. The Google developer documentation for the
service is publicly available on the Internet; see the Links
section for details.

WebClient web = new WebClient();
NameValueCollection postParams =
new NameValueCollection();
postParams.Add(“accountType”, accountType);
postParams.Add(“Email”, email);
postParams.Add(“Passwd”, password);
postParams.Add(“service”, service);
postParams.Add(“source”, sourceApp);
byte[] result = web.UploadValues(
loginUrl, “POST”, postParams);
string resultStr =
string[] tokens = resultStr.Split();
bloggerAuthToken = tokens[2].Substring(5);

With the authentication token available (the
bloggerAuthToken member at the end of the code snippet), the
next step is to call the actual posting function. This can
be done with code similar to the following:

public static void SubmitBlogPost(
string title, string body)
string xml;
MemoryStream xmlStream =
new MemoryStream();
XmlWriterSettings settings =
new XmlWriterSettings();
settings.Indent = true;
XmlWriter writer = XmlWriter.Create(
xmlStream, settings);
“entry”, “”);

xml = Encoding.ASCII.GetString(xmlStream.ToArray());
WebClient web = new WebClient();
web.Headers.Add(“Content-Type”, “application/atom+xml”);
web.Headers.Add(“Authorization”, “GoogleLogin auth=” +
web.Headers.Add(“GData-Version”, “2”);
web.Encoding = Encoding.UTF8;
string response = web.UploadString(submitUrl, “POST”, xml);

Here, the code first constructs an XML based Atom entry
that the Blogger service accepts (the actual lines are
omitted for brevity), and then uses a WebClient to connect
to the HTTP service. Note how several custom headers have to
be added to the HTTP request for the Google API to accept

Now that the code to submit a blog entry is in place,
next you need to notice when the Word document is being
saved. The Word object model supports a set of events, and
one of them is called DocumentBeforeSave. You can hook into
this event, and then execute the necessary code to update
the blog whenever the document has been saved.

The logical place to hook into this event is in
ThisAddIn.cs’ ThisAddIn_Startup method. Here is the code to
hook and handle the event:

private void ThisAddIn_Startup(
object sender, System.EventArgs e)
userControl = new SalesToolsUserControl();

handler = new ApplicationEvents4_
this.Application.DocumentBeforeSave += handler;

private void Application_DocumentBeforeSave(
Microsoft.Office.Interop.Word.Document Doc,
ref bool SaveAsUI, ref bool Cancel)
// the document is about to be saved
if (!SaveAsUI)
// not saving with a new name
// or for the first time

Once the event handler has been assigned to the event,
the Application_DocumentBeforeSave method is called each
time the user saves the document. Notice how a presentation
of the active document is passed to the event handler as the
Doc parameter. This object contains a property called
FullName, which is used when creating the blog entry text.
The code in the user control’s PublishSaveToBlog method
looks like the following:

public void PublishSaveToBlog(string filename)
if (publishToBlogCheckBox.Checked)
BloggerClient.SubmitBlogPost(“Offer updated”,
“The offer “” + filename +
“” has been updated.”);
MessageBox.Show(“Blog entry published!”);

The end result is a blog entry similar to the one in
Figure 9.

Figure 9. A submitted blog entry by the sample application.


In this article, you saw how you can use Visual Studio
2008 to create add-in applications for the Office 2007 suite
of products, and more specifically Word 2007. Visual Studio
2008 provides ready-made templates for developing such add-
ins, and this gives you a head start. Creating for example a
custom task panel is easy as adding a new user control to
the project, and then registering it with Word.

The sample application (Figure 10) showed you how you can
easily extend Word to transform it to a powerful application
platform: you can access SQL databases, call web services,
and even associate your code with events in Word. From this
perspective, the rule of thumb is that if you can do it
from .NET code, you can also do it from an Office add-in.

Click here for larger image

Figure 10. The sample application running inside Word 2007.

If you are looking to build your custom solutions to help
businesses run more efficiently, think about whether you
could integrate the needed functionality into Office
applications like Word, Excel, PowerPoint or Outlook. The
possibilities in both business and personal settings are
many. And once Visual Studio 2010 and Office 2010 become
available, the story will get even better. In the mean time,
let’s empower the office!

Resource Links

Office Development with Visual Studio
Office Developer Center
Word 2007 Developer Reference
Word Object Model Reference
Google Data APIs Overview

About the Author

Jani Järvinen is a software development trainer and
consultant in Finland. He is a Microsoft C# MVP and a
frequent author and has published three books about software
development. He is the group leader of a Finnish software
development expert group at and a board member of
the Finnish Visual Studio Team System User Group. His blog
can be found at http://www
. You can send him mail by clicking
on his name at the top of the article.

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