How-To: Enumerate the Internet Explorer Installed OpenSearch Engines

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For my recent Launcher project, I was constructing a ribbon that would allow the user to search the web via their engines installed in Internet Explorer. The engines themselves are an XML document following the OpenSearch schema. For firefox, these xml documents just get stored locally. What does IE do with theirs?

Well, IE sticks them in the registry. Why? Maybe someone else can answer that. Here's a brief look at how to get the search engines out of the registry. The following snippets of code come from the launcher project. If you want to see how I abstracted the engines and the complete code, you can download it from Codeplex. If you want to critique the code or make suggestions on how I can code better, leave me a comment here. I'm not the best programmer and I'm starving to learn.

First off, lets give a simple answer to this post: How do I enumerate the IE search engines? The search engines are located in Software\Microsoft\Internet Explorer\SearchScopes, the rest of the task is just enumerating the keys and values to extract important information.

First off, I made a straightforward structure to represent my individual search engine:

Public Structure SearchEngine
    Private m_DisplayName As String
    Public Property DisplayName() As String
        Get
            Return m_DisplayName
        End Get
        Set(ByVal value As String)
            m_DisplayName = value
        End Set
    End Property

    Private m_SearchString As String
    Public Property SearchString() As String
        Get
            Return m_SearchString
        End Get
        Set(ByVal value As String)
            m_SearchString = value
        End Set
    End Property

    Private m_isDefault As Boolean
    Public Property isDefault() As Boolean
        Get
            Return m_isDefault
        End Get
        Set(ByVal value As Boolean)
            m_isDefault = value
        End Set
    End Property

    Public Overrides Function ToString() As String
        Return m_DisplayName.ToString
    End Function
End Structure

This structure just contains the display name, the search string and whether or not it is the default.

I fill a list of search engines as so:

Private Sub GatherEnginesFromRegistry()
    'Clear list
    m_engineList.Clear()

    Dim regKey As RegistryKey = Registry.CurrentUser.OpenSubKey("Software\Microsoft\Internet Explorer\SearchScopes", False)
    'Gather Default key
    Dim defaultKey As String = regKey.GetValue("DefaultScope")

    'Gather all search engines
    For Each subKey As String In regKey.GetSubKeyNames
        Dim engine As New SearchEngine
        Dim engineKey As RegistryKey = regKey.OpenSubKey(subKey)
        If engineKey.GetValue("") = String.Empty Then
            engine.DisplayName = engineKey.GetValue("DisplayName")
        Else
            engine.DisplayName = engineKey.GetValue("")
        End If
        engine.SearchString = engineKey.GetValue("URL")
        If (subKey = defaultKey) Then
            engine.isDefault = True
        Else
            engine.isDefault = False
        End If
        m_engineList.Add(engine)
        engineKey.Close()
    Next

    regKey.Close()
End Sub

Here you see regKey as a key to the SearchScopes subkey within CURRENT_USER. Within SearchScopes the DefaultScope value contains the subkey name for the default search engine.

After fetching the name of the default engine, I just iterate through eachsubKey and convert it into my structure, and add it to a generic list. The important values being DisplayName and URL. However, if the (Default) value for the subkey is specified, I take it instead of the DisplayName. Why? because LiveSearch does this oddity:

The DisplayName is a DLL call of sorts and the (Default) is the name? What's up with that? :\

And finally, to use the search within an application just replace the {searchTerms} in the URL with the appropriate URI formatted text and send it on its way via Process.Start!

Private Sub btnSearch_Click(ByVal sender As System.Object, ByVal e As Microsoft.Office.Tools.Ribbon.RibbonControlEventArgs) Handles btnSearch.Click
    Process.Start(searchURL.Replace("{searchTerms}", ConvertStringToURI(searchText)))
End Sub